libavcodec/mpeg4videodec.c

   1 /*
   2  * MPEG-4 decoder
   3  * Copyright (c) 2000,2001 Fabrice Bellard
   4  * Copyright (c) 2002-2010 Michael Niedermayer <michaelni@gmx.at>
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #define UNCHECKED_BITSTREAM_READER 1
  24
  25 #include "libavutil/internal.h"
  26 #include "libavutil/opt.h"
  27 #include "error_resilience.h"
  28 #include "idctdsp.h"
  29 #include "internal.h"
  30 #include "mpegutils.h"
  31 #include "mpegvideo.h"
  32 #include "mpegvideodata.h"
  33 #include "mpeg4video.h"
  34 #include "h263.h"
  35 #include "profiles.h"
  36 #include "thread.h"
  37 #include "xvididct.h"
  38
  39 /* The defines below define the number of bits that are read at once for
  40  * reading vlc values. Changing these may improve speed and data cache needs
  41  * be aware though that decreasing them may need the number of stages that is
  42  * passed to get_vlc* to be increased. */
  43 #define SPRITE_TRAJ_VLC_BITS 6
  44 #define DC_VLC_BITS 9
  45 #define MB_TYPE_B_VLC_BITS 4
  46
  47 static VLC dc_lum, dc_chrom;
  48 static VLC sprite_trajectory;
  49 static VLC mb_type_b_vlc;
  50
  51 static const int mb_type_b_map[4] = {
  52     MB_TYPE_DIRECT2 | MB_TYPE_L0L1,
  53     MB_TYPE_L0L1    | MB_TYPE_16x16,
  54     MB_TYPE_L1      | MB_TYPE_16x16,
  55     MB_TYPE_L0      | MB_TYPE_16x16,
  56 };
  57
  58 /**
  59  * Predict the ac.
  60  * @param n block index (0-3 are luma, 4-5 are chroma)
  61  * @param dir the ac prediction direction
  62  */
  63 void ff_mpeg4_pred_ac(MpegEncContext *s, int16_t *block, int n, int dir)
  64 {
  65     int i;
  66     int16_t *ac_val, *ac_val1;
  67     int8_t *const qscale_table = s->current_picture.qscale_table;
  68
  69     /* find prediction */
  70     ac_val  = &s->ac_val[0][0][0] + s->block_index[n] * 16;
  71     ac_val1 = ac_val;
  72     if (s->ac_pred) {
  73         if (dir == 0) {
  74             const int xy = s->mb_x - 1 + s->mb_y * s->mb_stride;
  75             /* left prediction */
  76             ac_val -= 16;
  77
  78             if (s->mb_x == 0 || s->qscale == qscale_table[xy] ||
  79                 n == 1 || n == 3) {
  80                 /* same qscale */
  81                 for (i = 1; i < 8; i++)
  82                     block[s->idsp.idct_permutation[i << 3]] += ac_val[i];
  83             } else {
  84                 /* different qscale, we must rescale */
  85                 for (i = 1; i < 8; i++)
  86                     block[s->idsp.idct_permutation[i << 3]] += ROUNDED_DIV(ac_val[i] * qscale_table[xy], s->qscale);
  87             }
  88         } else {
  89             const int xy = s->mb_x + s->mb_y * s->mb_stride - s->mb_stride;
  90             /* top prediction */
  91             ac_val -= 16 * s->block_wrap[n];
  92
  93             if (s->mb_y == 0 || s->qscale == qscale_table[xy] ||
  94                 n == 2 || n == 3) {
  95                 /* same qscale */
  96                 for (i = 1; i < 8; i++)
  97                     block[s->idsp.idct_permutation[i]] += ac_val[i + 8];
  98             } else {
  99                 /* different qscale, we must rescale */
 100                 for (i = 1; i < 8; i++)
 101                     block[s->idsp.idct_permutation[i]] += ROUNDED_DIV(ac_val[i + 8] * qscale_table[xy], s->qscale);
 102             }
 103         }
 104     }
 105     /* left copy */
 106     for (i = 1; i < 8; i++)
 107         ac_val1[i] = block[s->idsp.idct_permutation[i << 3]];
 108
 109     /* top copy */
 110     for (i = 1; i < 8; i++)
 111         ac_val1[8 + i] = block[s->idsp.idct_permutation[i]];
 112 }
 113
 114 /**
 115  * check if the next stuff is a resync marker or the end.
 116  * @return 0 if not
 117  */
 118 static inline int mpeg4_is_resync(Mpeg4DecContext *ctx)
 119 {
 120     MpegEncContext *s = &ctx->m;
 121     int bits_count = get_bits_count(&s->gb);
 122     int v          = show_bits(&s->gb, 16);
 123
 124     if (s->workaround_bugs & FF_BUG_NO_PADDING && !ctx->resync_marker)
 125         return 0;
 126
 127     while (v <= 0xFF) {
 128         if (s->pict_type == AV_PICTURE_TYPE_B ||
 129             (v >> (8 - s->pict_type) != 1) || s->partitioned_frame)
 130             break;
 131         skip_bits(&s->gb, 8 + s->pict_type);
 132         bits_count += 8 + s->pict_type;
 133         v = show_bits(&s->gb, 16);
 134     }
 135
 136     if (bits_count + 8 >= s->gb.size_in_bits) {
 137         v >>= 8;
 138         v  |= 0x7F >> (7 - (bits_count & 7));
 139
 140         if (v == 0x7F)
 141             return s->mb_num;
 142     } else {
 143         if (v == ff_mpeg4_resync_prefix[bits_count & 7]) {
 144             int len, mb_num;
 145             int mb_num_bits = av_log2(s->mb_num - 1) + 1;
 146             GetBitContext gb = s->gb;
 147
 148             skip_bits(&s->gb, 1);
 149             align_get_bits(&s->gb);
 150
 151             for (len = 0; len < 32; len++)
 152                 if (get_bits1(&s->gb))
 153                     break;
 154
 155             mb_num = get_bits(&s->gb, mb_num_bits);
 156             if (!mb_num || mb_num > s->mb_num || get_bits_count(&s->gb)+6 > s->gb.size_in_bits)
 157                 mb_num= -1;
 158
 159             s->gb = gb;
 160
 161             if (len >= ff_mpeg4_get_video_packet_prefix_length(s))
 162                 return mb_num;
 163         }
 164     }
 165     return 0;
 166 }
 167
 168 static int mpeg4_decode_sprite_trajectory(Mpeg4DecContext *ctx, GetBitContext *gb)
 169 {
 170     MpegEncContext *s = &ctx->m;
 171     int a     = 2 << s->sprite_warping_accuracy;
 172     int rho   = 3  - s->sprite_warping_accuracy;
 173     int r     = 16 / a;
 174     int alpha = 0;
 175     int beta  = 0;
 176     int w     = s->width;
 177     int h     = s->height;
 178     int min_ab, i, w2, h2, w3, h3;
 179     int sprite_ref[4][2];
 180     int virtual_ref[2][2];
 181     int64_t sprite_offset[2][2];
 182
 183     // only true for rectangle shapes
 184     const int vop_ref[4][2] = { { 0, 0 },         { s->width, 0 },
 185                                 { 0, s->height }, { s->width, s->height } };
 186     int d[4][2]             = { { 0, 0 }, { 0, 0 }, { 0, 0 }, { 0, 0 } };
 187
 188     if (w <= 0 || h <= 0)
 189         return AVERROR_INVALIDDATA;
 190
 191     for (i = 0; i < ctx->num_sprite_warping_points; i++) {
 192         int length;
 193         int x = 0, y = 0;
 194
 195         length = get_vlc2(gb, sprite_trajectory.table, SPRITE_TRAJ_VLC_BITS, 3);
 196         if (length > 0)
 197             x = get_xbits(gb, length);
 198
 199         if (!(ctx->divx_version == 500 && ctx->divx_build == 413))
 200             check_marker(s->avctx, gb, "before sprite_trajectory");
 201
 202         length = get_vlc2(gb, sprite_trajectory.table, SPRITE_TRAJ_VLC_BITS, 3);
 203         if (length > 0)
 204             y = get_xbits(gb, length);
 205
 206         check_marker(s->avctx, gb, "after sprite_trajectory");
 207         ctx->sprite_traj[i][0] = d[i][0] = x;
 208         ctx->sprite_traj[i][1] = d[i][1] = y;
 209     }
 210     for (; i < 4; i++)
 211         ctx->sprite_traj[i][0] = ctx->sprite_traj[i][1] = 0;
 212
 213     while ((1 << alpha) < w)
 214         alpha++;
 215     while ((1 << beta) < h)
 216         beta++;  /* typo in the MPEG-4 std for the definition of w' and h' */
 217     w2 = 1 << alpha;
 218     h2 = 1 << beta;
 219
 220     // Note, the 4th point isn't used for GMC
 221     if (ctx->divx_version == 500 && ctx->divx_build == 413) {
 222         sprite_ref[0][0] = a * vop_ref[0][0] + d[0][0];
 223         sprite_ref[0][1] = a * vop_ref[0][1] + d[0][1];
 224         sprite_ref[1][0] = a * vop_ref[1][0] + d[0][0] + d[1][0];
 225         sprite_ref[1][1] = a * vop_ref[1][1] + d[0][1] + d[1][1];
 226         sprite_ref[2][0] = a * vop_ref[2][0] + d[0][0] + d[2][0];
 227         sprite_ref[2][1] = a * vop_ref[2][1] + d[0][1] + d[2][1];
 228     } else {
 229         sprite_ref[0][0] = (a >> 1) * (2 * vop_ref[0][0] + d[0][0]);
 230         sprite_ref[0][1] = (a >> 1) * (2 * vop_ref[0][1] + d[0][1]);
 231         sprite_ref[1][0] = (a >> 1) * (2 * vop_ref[1][0] + d[0][0] + d[1][0]);
 232         sprite_ref[1][1] = (a >> 1) * (2 * vop_ref[1][1] + d[0][1] + d[1][1]);
 233         sprite_ref[2][0] = (a >> 1) * (2 * vop_ref[2][0] + d[0][0] + d[2][0]);
 234         sprite_ref[2][1] = (a >> 1) * (2 * vop_ref[2][1] + d[0][1] + d[2][1]);
 235     }
 236     /* sprite_ref[3][0] = (a >> 1) * (2 * vop_ref[3][0] + d[0][0] + d[1][0] + d[2][0] + d[3][0]);
 237      * sprite_ref[3][1] = (a >> 1) * (2 * vop_ref[3][1] + d[0][1] + d[1][1] + d[2][1] + d[3][1]); */
 238
 239     /* This is mostly identical to the MPEG-4 std (and is totally unreadable
 240      * because of that...). Perhaps it should be reordered to be more readable.
 241      * The idea behind this virtual_ref mess is to be able to use shifts later
 242      * per pixel instead of divides so the distance between points is converted
 243      * from w&h based to w2&h2 based which are of the 2^x form. */
 244     virtual_ref[0][0] = 16 * (vop_ref[0][0] + w2) +
 245                          ROUNDED_DIV(((w - w2) *
 246                                       (r * sprite_ref[0][0] - 16 * vop_ref[0][0]) +
 247                                       w2 * (r * sprite_ref[1][0] - 16 * vop_ref[1][0])), w);
 248     virtual_ref[0][1] = 16 * vop_ref[0][1] +
 249                         ROUNDED_DIV(((w - w2) *
 250                                      (r * sprite_ref[0][1] - 16 * vop_ref[0][1]) +
 251                                      w2 * (r * sprite_ref[1][1] - 16 * vop_ref[1][1])), w);
 252     virtual_ref[1][0] = 16 * vop_ref[0][0] +
 253                         ROUNDED_DIV(((h - h2) * (r * sprite_ref[0][0] - 16 * vop_ref[0][0]) +
 254                                      h2 * (r * sprite_ref[2][0] - 16 * vop_ref[2][0])), h);
 255     virtual_ref[1][1] = 16 * (vop_ref[0][1] + h2) +
 256                         ROUNDED_DIV(((h - h2) * (r * sprite_ref[0][1] - 16 * vop_ref[0][1]) +
 257                                      h2 * (r * sprite_ref[2][1] - 16 * vop_ref[2][1])), h);
 258
 259     switch (ctx->num_sprite_warping_points) {
 260     case 0:
 261         sprite_offset[0][0]    =
 262         sprite_offset[0][1]    =
 263         sprite_offset[1][0]    =
 264         sprite_offset[1][1]    = 0;
 265         s->sprite_delta[0][0]  = a;
 266         s->sprite_delta[0][1]  =
 267         s->sprite_delta[1][0]  = 0;
 268         s->sprite_delta[1][1]  = a;
 269         ctx->sprite_shift[0]   =
 270         ctx->sprite_shift[1]   = 0;
 271         break;
 272     case 1:     // GMC only
 273         sprite_offset[0][0]    = sprite_ref[0][0] - a * vop_ref[0][0];
 274         sprite_offset[0][1]    = sprite_ref[0][1] - a * vop_ref[0][1];
 275         sprite_offset[1][0]    = ((sprite_ref[0][0] >> 1) | (sprite_ref[0][0] & 1)) -
 276                                  a * (vop_ref[0][0] / 2);
 277         sprite_offset[1][1]    = ((sprite_ref[0][1] >> 1) | (sprite_ref[0][1] & 1)) -
 278                                  a * (vop_ref[0][1] / 2);
 279         s->sprite_delta[0][0]  = a;
 280         s->sprite_delta[0][1]  =
 281         s->sprite_delta[1][0]  = 0;
 282         s->sprite_delta[1][1]  = a;
 283         ctx->sprite_shift[0]   =
 284         ctx->sprite_shift[1]   = 0;
 285         break;
 286     case 2:
 287         sprite_offset[0][0]    = (sprite_ref[0][0] * (1 << alpha + rho)) +
 288                                  (-r * sprite_ref[0][0] + virtual_ref[0][0]) *
 289                                  (-vop_ref[0][0]) +
 290                                  (r * sprite_ref[0][1] - virtual_ref[0][1]) *
 291                                  (-vop_ref[0][1]) + (1 << (alpha + rho - 1));
 292         sprite_offset[0][1]    = (sprite_ref[0][1] * (1 << alpha + rho)) +
 293                                  (-r * sprite_ref[0][1] + virtual_ref[0][1]) *
 294                                  (-vop_ref[0][0]) +
 295                                  (-r * sprite_ref[0][0] + virtual_ref[0][0]) *
 296                                  (-vop_ref[0][1]) + (1 << (alpha + rho - 1));
 297         sprite_offset[1][0]    = ((-r * sprite_ref[0][0] + virtual_ref[0][0]) *
 298                                   (-2 * vop_ref[0][0] + 1) +
 299                                   (r * sprite_ref[0][1] - virtual_ref[0][1]) *
 300                                   (-2 * vop_ref[0][1] + 1) + 2 * w2 * r *
 301                                   sprite_ref[0][0] - 16 * w2 + (1 << (alpha + rho + 1)));
 302         sprite_offset[1][1]    = ((-r * sprite_ref[0][1] + virtual_ref[0][1]) *
 303                                   (-2 * vop_ref[0][0] + 1) +
 304                                   (-r * sprite_ref[0][0] + virtual_ref[0][0]) *
 305                                   (-2 * vop_ref[0][1] + 1) + 2 * w2 * r *
 306                                   sprite_ref[0][1] - 16 * w2 + (1 << (alpha + rho + 1)));
 307         s->sprite_delta[0][0] = (-r * sprite_ref[0][0] + virtual_ref[0][0]);
 308         s->sprite_delta[0][1] = (+r * sprite_ref[0][1] - virtual_ref[0][1]);
 309         s->sprite_delta[1][0] = (-r * sprite_ref[0][1] + virtual_ref[0][1]);
 310         s->sprite_delta[1][1] = (-r * sprite_ref[0][0] + virtual_ref[0][0]);
 311
 312         ctx->sprite_shift[0]  = alpha + rho;
 313         ctx->sprite_shift[1]  = alpha + rho + 2;
 314         break;
 315     case 3:
 316         min_ab = FFMIN(alpha, beta);
 317         w3     = w2 >> min_ab;
 318         h3     = h2 >> min_ab;
 319         sprite_offset[0][0]    = ((int64_t)sprite_ref[0][0] * (1 << (alpha + beta + rho - min_ab))) +
 320                                  ((int64_t)-r * sprite_ref[0][0] + virtual_ref[0][0]) * h3 * (-vop_ref[0][0]) +
 321                                  ((int64_t)-r * sprite_ref[0][0] + virtual_ref[1][0]) * w3 * (-vop_ref[0][1]) +
 322                                  ((int64_t)1 << (alpha + beta + rho - min_ab - 1));
 323         sprite_offset[0][1]    = ((int64_t)sprite_ref[0][1] * (1 << (alpha + beta + rho - min_ab))) +
 324                                  ((int64_t)-r * sprite_ref[0][1] + virtual_ref[0][1]) * h3 * (-vop_ref[0][0]) +
 325                                  ((int64_t)-r * sprite_ref[0][1] + virtual_ref[1][1]) * w3 * (-vop_ref[0][1]) +
 326                                  ((int64_t)1 << (alpha + beta + rho - min_ab - 1));
 327         sprite_offset[1][0]    = ((int64_t)-r * sprite_ref[0][0] + virtual_ref[0][0]) * h3 * (-2 * vop_ref[0][0] + 1) +
 328                                  ((int64_t)-r * sprite_ref[0][0] + virtual_ref[1][0]) * w3 * (-2 * vop_ref[0][1] + 1) +
 329                                   (int64_t)2 * w2 * h3 * r * sprite_ref[0][0] - 16 * w2 * h3 +
 330                                  ((int64_t)1 << (alpha + beta + rho - min_ab + 1));
 331         sprite_offset[1][1]    = ((int64_t)-r * sprite_ref[0][1] + virtual_ref[0][1]) * h3 * (-2 * vop_ref[0][0] + 1) +
 332                                  ((int64_t)-r * sprite_ref[0][1] + virtual_ref[1][1]) * w3 * (-2 * vop_ref[0][1] + 1) +
 333                                   (int64_t)2 * w2 * h3 * r * sprite_ref[0][1] - 16 * w2 * h3 +
 334                                  ((int64_t)1 << (alpha + beta + rho - min_ab + 1));
 335         s->sprite_delta[0][0] = (-r * sprite_ref[0][0] + virtual_ref[0][0]) * h3;
 336         s->sprite_delta[0][1] = (-r * sprite_ref[0][0] + virtual_ref[1][0]) * w3;
 337         s->sprite_delta[1][0] = (-r * sprite_ref[0][1] + virtual_ref[0][1]) * h3;
 338         s->sprite_delta[1][1] = (-r * sprite_ref[0][1] + virtual_ref[1][1]) * w3;
 339
 340         ctx->sprite_shift[0]  = alpha + beta + rho - min_ab;
 341         ctx->sprite_shift[1]  = alpha + beta + rho - min_ab + 2;
 342         break;
 343     }
 344     /* try to simplify the situation */
 345     if (s->sprite_delta[0][0] == a << ctx->sprite_shift[0] &&
 346         s->sprite_delta[0][1] == 0 &&
 347         s->sprite_delta[1][0] == 0 &&
 348         s->sprite_delta[1][1] == a << ctx->sprite_shift[0]) {
 349         sprite_offset[0][0] >>= ctx->sprite_shift[0];
 350         sprite_offset[0][1] >>= ctx->sprite_shift[0];
 351         sprite_offset[1][0] >>= ctx->sprite_shift[1];
 352         sprite_offset[1][1] >>= ctx->sprite_shift[1];
 353         s->sprite_delta[0][0] = a;
 354         s->sprite_delta[0][1] = 0;
 355         s->sprite_delta[1][0] = 0;
 356         s->sprite_delta[1][1] = a;
 357         ctx->sprite_shift[0] = 0;
 358         ctx->sprite_shift[1] = 0;
 359         s->real_sprite_warping_points = 1;
 360     } else {
 361         int shift_y = 16 - ctx->sprite_shift[0];
 362         int shift_c = 16 - ctx->sprite_shift[1];
 363
 364         if (shift_c < 0 || shift_y < 0 ||
 365             FFABS(sprite_offset[0][0]) >= INT_MAX >> shift_y  ||
 366             FFABS(sprite_offset[1][0]) >= INT_MAX >> shift_c  ||
 367             FFABS(sprite_offset[0][1]) >= INT_MAX >> shift_y  ||
 368             FFABS(sprite_offset[1][1]) >= INT_MAX >> shift_c
 369         ) {
 370             avpriv_request_sample(s->avctx, "Too large sprite shift or offset");
 371             goto overflow;
 372         }
 373
 374         for (i = 0; i < 2; i++) {
 375             sprite_offset[0][i]    *= 1 << shift_y;
 376             sprite_offset[1][i]    *= 1 << shift_c;
 377             s->sprite_delta[0][i]  *= 1 << shift_y;
 378             s->sprite_delta[1][i]  *= 1 << shift_y;
 379             ctx->sprite_shift[i]     = 16;
 380
 381         }
 382         for (i = 0; i < 2; i++) {
 383             int64_t sd[2] = {
 384                 s->sprite_delta[i][0] - a * (1LL<<16),
 385                 s->sprite_delta[i][1] - a * (1LL<<16)
 386             };
 387
 388             if (llabs(sprite_offset[0][i] + s->sprite_delta[i][0] * (w+16LL)) >= INT_MAX ||
 389                 llabs(sprite_offset[0][i] + s->sprite_delta[i][1] * (h+16LL)) >= INT_MAX ||
 390                 llabs(sprite_offset[0][i] + s->sprite_delta[i][0] * (w+16LL) + s->sprite_delta[i][1] * (h+16LL)) >= INT_MAX ||
 391                 llabs(s->sprite_delta[i][0] * (w+16LL)) >= INT_MAX ||
 392                 llabs(s->sprite_delta[i][1] * (w+16LL)) >= INT_MAX ||
 393                 llabs(sd[0]) >= INT_MAX ||
 394                 llabs(sd[1]) >= INT_MAX ||
 395                 llabs(sprite_offset[0][i] + sd[0] * (w+16LL)) >= INT_MAX ||
 396                 llabs(sprite_offset[0][i] + sd[1] * (h+16LL)) >= INT_MAX ||
 397                 llabs(sprite_offset[0][i] + sd[0] * (w+16LL) + sd[1] * (h+16LL)) >= INT_MAX
 398             ) {
 399                 avpriv_request_sample(s->avctx, "Overflow on sprite points");
 400                 goto overflow;
 401             }
 402         }
 403         s->real_sprite_warping_points = ctx->num_sprite_warping_points;
 404     }
 405
 406     s->sprite_offset[0][0] = sprite_offset[0][0];
 407     s->sprite_offset[0][1] = sprite_offset[0][1];
 408     s->sprite_offset[1][0] = sprite_offset[1][0];
 409     s->sprite_offset[1][1] = sprite_offset[1][1];
 410
 411     return 0;
 412 overflow:
 413     memset(s->sprite_offset, 0, sizeof(s->sprite_offset));
 414     memset(s->sprite_delta, 0, sizeof(s->sprite_delta));
 415     return AVERROR_PATCHWELCOME;
 416 }
 417
 418 static int decode_new_pred(Mpeg4DecContext *ctx, GetBitContext *gb) {
 419     MpegEncContext *s = &ctx->m;
 420     int len = FFMIN(ctx->time_increment_bits + 3, 15);
 421
 422     get_bits(gb, len);
 423     if (get_bits1(gb))
 424         get_bits(gb, len);
 425     check_marker(s->avctx, gb, "after new_pred");
 426
 427     return 0;
 428 }
 429
 430 /**
 431  * Decode the next video packet.
 432  * @return <0 if something went wrong
 433  */
 434 int ff_mpeg4_decode_video_packet_header(Mpeg4DecContext *ctx)
 435 {
 436     MpegEncContext *s = &ctx->m;
 437
 438     int mb_num_bits      = av_log2(s->mb_num - 1) + 1;
 439     int header_extension = 0, mb_num, len;
 440
 441     /* is there enough space left for a video packet + header */
 442     if (get_bits_count(&s->gb) > s->gb.size_in_bits - 20)
 443         return -1;
 444
 445     for (len = 0; len < 32; len++)
 446         if (get_bits1(&s->gb))
 447             break;
 448
 449     if (len != ff_mpeg4_get_video_packet_prefix_length(s)) {
 450         av_log(s->avctx, AV_LOG_ERROR, "marker does not match f_code\n");
 451         return -1;
 452     }
 453
 454     if (ctx->shape != RECT_SHAPE) {
 455         header_extension = get_bits1(&s->gb);
 456         // FIXME more stuff here
 457     }
 458
 459     mb_num = get_bits(&s->gb, mb_num_bits);
 460     if (mb_num >= s->mb_num) {
 461         av_log(s->avctx, AV_LOG_ERROR,
 462                "illegal mb_num in video packet (%d %d) \n", mb_num, s->mb_num);
 463         return -1;
 464     }
 465
 466     s->mb_x = mb_num % s->mb_width;
 467     s->mb_y = mb_num / s->mb_width;
 468
 469     if (ctx->shape != BIN_ONLY_SHAPE) {
 470         int qscale = get_bits(&s->gb, s->quant_precision);
 471         if (qscale)
 472             s->chroma_qscale = s->qscale = qscale;
 473     }
 474
 475     if (ctx->shape == RECT_SHAPE)
 476         header_extension = get_bits1(&s->gb);
 477
 478     if (header_extension) {
 479         int time_incr = 0;
 480
 481         while (get_bits1(&s->gb) != 0)
 482             time_incr++;
 483
 484         check_marker(s->avctx, &s->gb, "before time_increment in video packed header");
 485         skip_bits(&s->gb, ctx->time_increment_bits);      /* time_increment */
 486         check_marker(s->avctx, &s->gb, "before vop_coding_type in video packed header");
 487
 488         skip_bits(&s->gb, 2); /* vop coding type */
 489         // FIXME not rect stuff here
 490
 491         if (ctx->shape != BIN_ONLY_SHAPE) {
 492             skip_bits(&s->gb, 3); /* intra dc vlc threshold */
 493             // FIXME don't just ignore everything
 494             if (s->pict_type == AV_PICTURE_TYPE_S &&
 495                 ctx->vol_sprite_usage == GMC_SPRITE) {
 496                 if (mpeg4_decode_sprite_trajectory(ctx, &s->gb) < 0)
 497                     return AVERROR_INVALIDDATA;
 498                 av_log(s->avctx, AV_LOG_ERROR, "untested\n");
 499             }
 500
 501             // FIXME reduced res stuff here
 502
 503             if (s->pict_type != AV_PICTURE_TYPE_I) {
 504                 int f_code = get_bits(&s->gb, 3);       /* fcode_for */
 505                 if (f_code == 0)
 506                     av_log(s->avctx, AV_LOG_ERROR,
 507                            "Error, video packet header damaged (f_code=0)\n");
 508             }
 509             if (s->pict_type == AV_PICTURE_TYPE_B) {
 510                 int b_code = get_bits(&s->gb, 3);
 511                 if (b_code == 0)
 512                     av_log(s->avctx, AV_LOG_ERROR,
 513                            "Error, video packet header damaged (b_code=0)\n");
 514             }
 515         }
 516     }
 517     if (ctx->new_pred)
 518         decode_new_pred(ctx, &s->gb);
 519
 520     return 0;
 521 }
 522
 523 /**
 524  * Get the average motion vector for a GMC MB.
 525  * @param n either 0 for the x component or 1 for y
 526  * @return the average MV for a GMC MB
 527  */
 528 static inline int get_amv(Mpeg4DecContext *ctx, int n)
 529 {
 530     MpegEncContext *s = &ctx->m;
 531     int x, y, mb_v, sum, dx, dy, shift;
 532     int len     = 1 << (s->f_code + 4);
 533     const int a = s->sprite_warping_accuracy;
 534
 535     if (s->workaround_bugs & FF_BUG_AMV)
 536         len >>= s->quarter_sample;
 537
 538     if (s->real_sprite_warping_points == 1) {
 539         if (ctx->divx_version == 500 && ctx->divx_build == 413)
 540             sum = s->sprite_offset[0][n] / (1 << (a - s->quarter_sample));
 541         else
 542             sum = RSHIFT(s->sprite_offset[0][n] * (1 << s->quarter_sample), a);
 543     } else {
 544         dx    = s->sprite_delta[n][0];
 545         dy    = s->sprite_delta[n][1];
 546         shift = ctx->sprite_shift[0];
 547         if (n)
 548             dy -= 1 << (shift + a + 1);
 549         else
 550             dx -= 1 << (shift + a + 1);
 551         mb_v = s->sprite_offset[0][n] + dx * s->mb_x * 16 + dy * s->mb_y * 16;
 552
 553         sum = 0;
 554         for (y = 0; y < 16; y++) {
 555             int v;
 556
 557             v = mb_v + dy * y;
 558             // FIXME optimize
 559             for (x = 0; x < 16; x++) {
 560                 sum += v >> shift;
 561                 v   += dx;
 562             }
 563         }
 564         sum = RSHIFT(sum, a + 8 - s->quarter_sample);
 565     }
 566
 567     if (sum < -len)
 568         sum = -len;
 569     else if (sum >= len)
 570         sum = len - 1;
 571
 572     return sum;
 573 }
 574
 575 /**
 576  * Decode the dc value.
 577  * @param n block index (0-3 are luma, 4-5 are chroma)
 578  * @param dir_ptr the prediction direction will be stored here
 579  * @return the quantized dc
 580  */
 581 static inline int mpeg4_decode_dc(MpegEncContext *s, int n, int *dir_ptr)
 582 {
 583     int level, code;
 584
 585     if (n < 4)
 586         code = get_vlc2(&s->gb, dc_lum.table, DC_VLC_BITS, 1);
 587     else
 588         code = get_vlc2(&s->gb, dc_chrom.table, DC_VLC_BITS, 1);
 589
 590     if (code < 0 || code > 9 /* && s->nbit < 9 */) {
 591         av_log(s->avctx, AV_LOG_ERROR, "illegal dc vlc\n");
 592         return -1;
 593     }
 594
 595     if (code == 0) {
 596         level = 0;
 597     } else {
 598         if (IS_3IV1) {
 599             if (code == 1)
 600                 level = 2 * get_bits1(&s->gb) - 1;
 601             else {
 602                 if (get_bits1(&s->gb))
 603                     level = get_bits(&s->gb, code - 1) + (1 << (code - 1));
 604                 else
 605                     level = -get_bits(&s->gb, code - 1) - (1 << (code - 1));
 606             }
 607         } else {
 608             level = get_xbits(&s->gb, code);
 609         }
 610
 611         if (code > 8) {
 612             if (get_bits1(&s->gb) == 0) { /* marker */
 613                 if (s->avctx->err_recognition & (AV_EF_BITSTREAM|AV_EF_COMPLIANT)) {
 614                     av_log(s->avctx, AV_LOG_ERROR, "dc marker bit missing\n");
 615                     return -1;
 616                 }
 617             }
 618         }
 619     }
 620
 621     return ff_mpeg4_pred_dc(s, n, level, dir_ptr, 0);
 622 }
 623
 624 /**
 625  * Decode first partition.
 626  * @return number of MBs decoded or <0 if an error occurred
 627  */
 628 static int mpeg4_decode_partition_a(Mpeg4DecContext *ctx)
 629 {
 630     MpegEncContext *s = &ctx->m;
 631     int mb_num = 0;
 632     static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
 633
 634     /* decode first partition */
 635     s->first_slice_line = 1;
 636     for (; s->mb_y < s->mb_height; s->mb_y++) {
 637         ff_init_block_index(s);
 638         for (; s->mb_x < s->mb_width; s->mb_x++) {
 639             const int xy = s->mb_x + s->mb_y * s->mb_stride;
 640             int cbpc;
 641             int dir = 0;
 642
 643             mb_num++;
 644             ff_update_block_index(s);
 645             if (s->mb_x == s->resync_mb_x && s->mb_y == s->resync_mb_y + 1)
 646                 s->first_slice_line = 0;
 647
 648             if (s->pict_type == AV_PICTURE_TYPE_I) {
 649                 int i;
 650
 651                 do {
 652                     if (show_bits_long(&s->gb, 19) == DC_MARKER)
 653                         return mb_num - 1;
 654
 655                     cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
 656                     if (cbpc < 0) {
 657                         av_log(s->avctx, AV_LOG_ERROR,
 658                                "mcbpc corrupted at %d %d\n", s->mb_x, s->mb_y);
 659                         return -1;
 660                     }
 661                 } while (cbpc == 8);
 662
 663                 s->cbp_table[xy]               = cbpc & 3;
 664                 s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
 665                 s->mb_intra                    = 1;
 666
 667                 if (cbpc & 4)
 668                     ff_set_qscale(s, s->qscale + quant_tab[get_bits(&s->gb, 2)]);
 669
 670                 s->current_picture.qscale_table[xy] = s->qscale;
 671
 672                 s->mbintra_table[xy] = 1;
 673                 for (i = 0; i < 6; i++) {
 674                     int dc_pred_dir;
 675                     int dc = mpeg4_decode_dc(s, i, &dc_pred_dir);
 676                     if (dc < 0) {
 677                         av_log(s->avctx, AV_LOG_ERROR,
 678                                "DC corrupted at %d %d\n", s->mb_x, s->mb_y);
 679                         return -1;
 680                     }
 681                     dir <<= 1;
 682                     if (dc_pred_dir)
 683                         dir |= 1;
 684                 }
 685                 s->pred_dir_table[xy] = dir;
 686             } else { /* P/S_TYPE */
 687                 int mx, my, pred_x, pred_y, bits;
 688                 int16_t *const mot_val = s->current_picture.motion_val[0][s->block_index[0]];
 689                 const int stride       = s->b8_stride * 2;
 690
 691 try_again:
 692                 bits = show_bits(&s->gb, 17);
 693                 if (bits == MOTION_MARKER)
 694                     return mb_num - 1;
 695
 696                 skip_bits1(&s->gb);
 697                 if (bits & 0x10000) {
 698                     /* skip mb */
 699                     if (s->pict_type == AV_PICTURE_TYPE_S &&
 700                         ctx->vol_sprite_usage == GMC_SPRITE) {
 701                         s->current_picture.mb_type[xy] = MB_TYPE_SKIP  |
 702                                                          MB_TYPE_16x16 |
 703                                                          MB_TYPE_GMC   |
 704                                                          MB_TYPE_L0;
 705                         mx = get_amv(ctx, 0);
 706                         my = get_amv(ctx, 1);
 707                     } else {
 708                         s->current_picture.mb_type[xy] = MB_TYPE_SKIP  |
 709                                                          MB_TYPE_16x16 |
 710                                                          MB_TYPE_L0;
 711                         mx = my = 0;
 712                     }
 713                     mot_val[0]          =
 714                     mot_val[2]          =
 715                     mot_val[0 + stride] =
 716                     mot_val[2 + stride] = mx;
 717                     mot_val[1]          =
 718                     mot_val[3]          =
 719                     mot_val[1 + stride] =
 720                     mot_val[3 + stride] = my;
 721
 722                     if (s->mbintra_table[xy])
 723                         ff_clean_intra_table_entries(s);
 724                     continue;
 725                 }
 726
 727                 cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
 728                 if (cbpc < 0) {
 729                     av_log(s->avctx, AV_LOG_ERROR,
 730                            "mcbpc corrupted at %d %d\n", s->mb_x, s->mb_y);
 731                     return -1;
 732                 }
 733                 if (cbpc == 20)
 734                     goto try_again;
 735
 736                 s->cbp_table[xy] = cbpc & (8 + 3);  // 8 is dquant
 737
 738                 s->mb_intra = ((cbpc & 4) != 0);
 739
 740                 if (s->mb_intra) {
 741                     s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
 742                     s->mbintra_table[xy] = 1;
 743                     mot_val[0]          =
 744                     mot_val[2]          =
 745                     mot_val[0 + stride] =
 746                     mot_val[2 + stride] = 0;
 747                     mot_val[1]          =
 748                     mot_val[3]          =
 749                     mot_val[1 + stride] =
 750                     mot_val[3 + stride] = 0;
 751                 } else {
 752                     if (s->mbintra_table[xy])
 753                         ff_clean_intra_table_entries(s);
 754
 755                     if (s->pict_type == AV_PICTURE_TYPE_S &&
 756                         ctx->vol_sprite_usage == GMC_SPRITE &&
 757                         (cbpc & 16) == 0)
 758                         s->mcsel = get_bits1(&s->gb);
 759                     else
 760                         s->mcsel = 0;
 761
 762                     if ((cbpc & 16) == 0) {
 763                         /* 16x16 motion prediction */
 764
 765                         ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
 766                         if (!s->mcsel) {
 767                             mx = ff_h263_decode_motion(s, pred_x, s->f_code);
 768                             if (mx >= 0xffff)
 769                                 return -1;
 770
 771                             my = ff_h263_decode_motion(s, pred_y, s->f_code);
 772                             if (my >= 0xffff)
 773                                 return -1;
 774                             s->current_picture.mb_type[xy] = MB_TYPE_16x16 |
 775                                                              MB_TYPE_L0;
 776                         } else {
 777                             mx = get_amv(ctx, 0);
 778                             my = get_amv(ctx, 1);
 779                             s->current_picture.mb_type[xy] = MB_TYPE_16x16 |
 780                                                              MB_TYPE_GMC   |
 781                                                              MB_TYPE_L0;
 782                         }
 783
 784                         mot_val[0]          =
 785                         mot_val[2]          =
 786                         mot_val[0 + stride] =
 787                         mot_val[2 + stride] = mx;
 788                         mot_val[1]          =
 789                         mot_val[3]          =
 790                         mot_val[1 + stride] =
 791                         mot_val[3 + stride] = my;
 792                     } else {
 793                         int i;
 794                         s->current_picture.mb_type[xy] = MB_TYPE_8x8 |
 795                                                          MB_TYPE_L0;
 796                         for (i = 0; i < 4; i++) {
 797                             int16_t *mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
 798                             mx = ff_h263_decode_motion(s, pred_x, s->f_code);
 799                             if (mx >= 0xffff)
 800                                 return -1;
 801
 802                             my = ff_h263_decode_motion(s, pred_y, s->f_code);
 803                             if (my >= 0xffff)
 804                                 return -1;
 805                             mot_val[0] = mx;
 806                             mot_val[1] = my;
 807                         }
 808                     }
 809                 }
 810             }
 811         }
 812         s->mb_x = 0;
 813     }
 814
 815     return mb_num;
 816 }
 817
 818 /**
 819  * decode second partition.
 820  * @return <0 if an error occurred
 821  */
 822 static int mpeg4_decode_partition_b(MpegEncContext *s, int mb_count)
 823 {
 824     int mb_num = 0;
 825     static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
 826
 827     s->mb_x = s->resync_mb_x;
 828     s->first_slice_line = 1;
 829     for (s->mb_y = s->resync_mb_y; mb_num < mb_count; s->mb_y++) {
 830         ff_init_block_index(s);
 831         for (; mb_num < mb_count && s->mb_x < s->mb_width; s->mb_x++) {
 832             const int xy = s->mb_x + s->mb_y * s->mb_stride;
 833
 834             mb_num++;
 835             ff_update_block_index(s);
 836             if (s->mb_x == s->resync_mb_x && s->mb_y == s->resync_mb_y + 1)
 837                 s->first_slice_line = 0;
 838
 839             if (s->pict_type == AV_PICTURE_TYPE_I) {
 840                 int ac_pred = get_bits1(&s->gb);
 841                 int cbpy    = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
 842                 if (cbpy < 0) {
 843                     av_log(s->avctx, AV_LOG_ERROR,
 844                            "cbpy corrupted at %d %d\n", s->mb_x, s->mb_y);
 845                     return -1;
 846                 }
 847
 848                 s->cbp_table[xy]               |= cbpy << 2;
 849                 s->current_picture.mb_type[xy] |= ac_pred * MB_TYPE_ACPRED;
 850             } else { /* P || S_TYPE */
 851                 if (IS_INTRA(s->current_picture.mb_type[xy])) {
 852                     int i;
 853                     int dir     = 0;
 854                     int ac_pred = get_bits1(&s->gb);
 855                     int cbpy    = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
 856
 857                     if (cbpy < 0) {
 858                         av_log(s->avctx, AV_LOG_ERROR,
 859                                "I cbpy corrupted at %d %d\n", s->mb_x, s->mb_y);
 860                         return -1;
 861                     }
 862
 863                     if (s->cbp_table[xy] & 8)
 864                         ff_set_qscale(s, s->qscale + quant_tab[get_bits(&s->gb, 2)]);
 865                     s->current_picture.qscale_table[xy] = s->qscale;
 866
 867                     for (i = 0; i < 6; i++) {
 868                         int dc_pred_dir;
 869                         int dc = mpeg4_decode_dc(s, i, &dc_pred_dir);
 870                         if (dc < 0) {
 871                             av_log(s->avctx, AV_LOG_ERROR,
 872                                    "DC corrupted at %d %d\n", s->mb_x, s->mb_y);
 873                             return -1;
 874                         }
 875                         dir <<= 1;
 876                         if (dc_pred_dir)
 877                             dir |= 1;
 878                     }
 879                     s->cbp_table[xy]               &= 3;  // remove dquant
 880                     s->cbp_table[xy]               |= cbpy << 2;
 881                     s->current_picture.mb_type[xy] |= ac_pred * MB_TYPE_ACPRED;
 882                     s->pred_dir_table[xy]           = dir;
 883                 } else if (IS_SKIP(s->current_picture.mb_type[xy])) {
 884                     s->current_picture.qscale_table[xy] = s->qscale;
 885                     s->cbp_table[xy]                    = 0;
 886                 } else {
 887                     int cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
 888
 889                     if (cbpy < 0) {
 890                         av_log(s->avctx, AV_LOG_ERROR,
 891                                "P cbpy corrupted at %d %d\n", s->mb_x, s->mb_y);
 892                         return -1;
 893                     }
 894
 895                     if (s->cbp_table[xy] & 8)
 896                         ff_set_qscale(s, s->qscale + quant_tab[get_bits(&s->gb, 2)]);
 897                     s->current_picture.qscale_table[xy] = s->qscale;
 898
 899                     s->cbp_table[xy] &= 3;  // remove dquant
 900                     s->cbp_table[xy] |= (cbpy ^ 0xf) << 2;
 901                 }
 902             }
 903         }
 904         if (mb_num >= mb_count)
 905             return 0;
 906         s->mb_x = 0;
 907     }
 908     return 0;
 909 }
 910
 911 /**
 912  * Decode the first and second partition.
 913  * @return <0 if error (and sets error type in the error_status_table)
 914  */
 915 int ff_mpeg4_decode_partitions(Mpeg4DecContext *ctx)
 916 {
 917     MpegEncContext *s = &ctx->m;
 918     int mb_num;
 919     const int part_a_error = s->pict_type == AV_PICTURE_TYPE_I ? (ER_DC_ERROR | ER_MV_ERROR) : ER_MV_ERROR;
 920     const int part_a_end   = s->pict_type == AV_PICTURE_TYPE_I ? (ER_DC_END   | ER_MV_END)   : ER_MV_END;
 921
 922     mb_num = mpeg4_decode_partition_a(ctx);
 923     if (mb_num <= 0) {
 924         ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y,
 925                         s->mb_x, s->mb_y, part_a_error);
 926         return -1;
 927     }
 928
 929     if (s->resync_mb_x + s->resync_mb_y * s->mb_width + mb_num > s->mb_num) {
 930         av_log(s->avctx, AV_LOG_ERROR, "slice below monitor ...\n");
 931         ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y,
 932                         s->mb_x, s->mb_y, part_a_error);
 933         return -1;
 934     }
 935
 936     s->mb_num_left = mb_num;
 937
 938     if (s->pict_type == AV_PICTURE_TYPE_I) {
 939         while (show_bits(&s->gb, 9) == 1)
 940             skip_bits(&s->gb, 9);
 941         if (get_bits_long(&s->gb, 19) != DC_MARKER) {
 942             av_log(s->avctx, AV_LOG_ERROR,
 943                    "marker missing after first I partition at %d %d\n",
 944                    s->mb_x, s->mb_y);
 945             return -1;
 946         }
 947     } else {
 948         while (show_bits(&s->gb, 10) == 1)
 949             skip_bits(&s->gb, 10);
 950         if (get_bits(&s->gb, 17) != MOTION_MARKER) {
 951             av_log(s->avctx, AV_LOG_ERROR,
 952                    "marker missing after first P partition at %d %d\n",
 953                    s->mb_x, s->mb_y);
 954             return -1;
 955         }
 956     }
 957     ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y,
 958                     s->mb_x - 1, s->mb_y, part_a_end);
 959
 960     if (mpeg4_decode_partition_b(s, mb_num) < 0) {
 961         if (s->pict_type == AV_PICTURE_TYPE_P)
 962             ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y,
 963                             s->mb_x, s->mb_y, ER_DC_ERROR);
 964         return -1;
 965     } else {
 966         if (s->pict_type == AV_PICTURE_TYPE_P)
 967             ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y,
 968                             s->mb_x - 1, s->mb_y, ER_DC_END);
 969     }
 970
 971     return 0;
 972 }
 973
 974 /**
 975  * Decode a block.
 976  * @return <0 if an error occurred
 977  */
 978 static inline int mpeg4_decode_block(Mpeg4DecContext *ctx, int16_t *block,
 979                                      int n, int coded, int intra, int rvlc)
 980 {
 981     MpegEncContext *s = &ctx->m;
 982     int level, i, last, run, qmul, qadd;
 983     int av_uninit(dc_pred_dir);
 984     RLTable *rl;
 985     RL_VLC_ELEM *rl_vlc;
 986     const uint8_t *scan_table;
 987
 988     // Note intra & rvlc should be optimized away if this is inlined
 989
 990     if (intra) {
 991         if (ctx->use_intra_dc_vlc) {
 992             /* DC coef */
 993             if (s->partitioned_frame) {
 994                 level = s->dc_val[0][s->block_index[n]];
 995                 if (n < 4)
 996                     level = FASTDIV((level + (s->y_dc_scale >> 1)), s->y_dc_scale);
 997                 else
 998                     level = FASTDIV((level + (s->c_dc_scale >> 1)), s->c_dc_scale);
 999                 dc_pred_dir = (s->pred_dir_table[s->mb_x + s->mb_y * s->mb_stride] << n) & 32;
1000             } else {
1001                 level = mpeg4_decode_dc(s, n, &dc_pred_dir);
1002                 if (level < 0)
1003                     return -1;
1004             }
1005             block[0] = level;
1006             i        = 0;
1007         } else {
1008             i = -1;
1009             ff_mpeg4_pred_dc(s, n, 0, &dc_pred_dir, 0);
1010         }
1011         if (!coded)
1012             goto not_coded;
1013
1014         if (rvlc) {
1015             rl     = &ff_rvlc_rl_intra;
1016             rl_vlc = ff_rvlc_rl_intra.rl_vlc[0];
1017         } else {
1018             rl     = &ff_mpeg4_rl_intra;
1019             rl_vlc = ff_mpeg4_rl_intra.rl_vlc[0];
1020         }
1021         if (s->ac_pred) {
1022             if (dc_pred_dir == 0)
1023                 scan_table = s->intra_v_scantable.permutated;  /* left */
1024             else
1025                 scan_table = s->intra_h_scantable.permutated;  /* top */
1026         } else {
1027             scan_table = s->intra_scantable.permutated;
1028         }
1029         qmul = 1;
1030         qadd = 0;
1031     } else {
1032         i = -1;
1033         if (!coded) {
1034             s->block_last_index[n] = i;
1035             return 0;
1036         }
1037         if (rvlc)
1038             rl = &ff_rvlc_rl_inter;
1039         else
1040             rl = &ff_h263_rl_inter;
1041
1042         scan_table = s->intra_scantable.permutated;
1043
1044         if (s->mpeg_quant) {
1045             qmul = 1;
1046             qadd = 0;
1047             if (rvlc)
1048                 rl_vlc = ff_rvlc_rl_inter.rl_vlc[0];
1049             else
1050                 rl_vlc = ff_h263_rl_inter.rl_vlc[0];
1051         } else {
1052             qmul = s->qscale << 1;
1053             qadd = (s->qscale - 1) | 1;
1054             if (rvlc)
1055                 rl_vlc = ff_rvlc_rl_inter.rl_vlc[s->qscale];
1056             else
1057                 rl_vlc = ff_h263_rl_inter.rl_vlc[s->qscale];
1058         }
1059     }
1060     {
1061         OPEN_READER(re, &s->gb);
1062         for (;;) {
1063             UPDATE_CACHE(re, &s->gb);
1064             GET_RL_VLC(level, run, re, &s->gb, rl_vlc, TEX_VLC_BITS, 2, 0);
1065             if (level == 0) {
1066                 /* escape */
1067                 if (rvlc) {
1068                     if (SHOW_UBITS(re, &s->gb, 1) == 0) {
1069                         av_log(s->avctx, AV_LOG_ERROR,
1070                                "1. marker bit missing in rvlc esc\n");
1071                         return -1;
1072                     }
1073                     SKIP_CACHE(re, &s->gb, 1);
1074
1075                     last = SHOW_UBITS(re, &s->gb, 1);
1076                     SKIP_CACHE(re, &s->gb, 1);
1077                     run = SHOW_UBITS(re, &s->gb, 6);
1078                     SKIP_COUNTER(re, &s->gb, 1 + 1 + 6);
1079                     UPDATE_CACHE(re, &s->gb);
1080
1081                     if (SHOW_UBITS(re, &s->gb, 1) == 0) {
1082                         av_log(s->avctx, AV_LOG_ERROR,
1083                                "2. marker bit missing in rvlc esc\n");
1084                         return -1;
1085                     }
1086                     SKIP_CACHE(re, &s->gb, 1);
1087
1088                     level = SHOW_UBITS(re, &s->gb, 11);
1089                     SKIP_CACHE(re, &s->gb, 11);
1090
1091                     if (SHOW_UBITS(re, &s->gb, 5) != 0x10) {
1092                         av_log(s->avctx, AV_LOG_ERROR, "reverse esc missing\n");
1093                         return -1;
1094                     }
1095                     SKIP_CACHE(re, &s->gb, 5);
1096
1097                     level = level * qmul + qadd;
1098                     level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
1099                     SKIP_COUNTER(re, &s->gb, 1 + 11 + 5 + 1);
1100
1101                     i += run + 1;
1102                     if (last)
1103                         i += 192;
1104                 } else {
1105                     int cache;
1106                     cache = GET_CACHE(re, &s->gb);
1107
1108                     if (IS_3IV1)
1109                         cache ^= 0xC0000000;
1110
1111                     if (cache & 0x80000000) {
1112                         if (cache & 0x40000000) {
1113                             /* third escape */
1114                             SKIP_CACHE(re, &s->gb, 2);
1115                             last = SHOW_UBITS(re, &s->gb, 1);
1116                             SKIP_CACHE(re, &s->gb, 1);
1117                             run = SHOW_UBITS(re, &s->gb, 6);
1118                             SKIP_COUNTER(re, &s->gb, 2 + 1 + 6);
1119                             UPDATE_CACHE(re, &s->gb);
1120
1121                             if (IS_3IV1) {
1122                                 level = SHOW_SBITS(re, &s->gb, 12);
1123                                 LAST_SKIP_BITS(re, &s->gb, 12);
1124                             } else {
1125                                 if (SHOW_UBITS(re, &s->gb, 1) == 0) {
1126                                     av_log(s->avctx, AV_LOG_ERROR,
1127                                            "1. marker bit missing in 3. esc\n");
1128                                     if (!(s->avctx->err_recognition & AV_EF_IGNORE_ERR))
1129                                         return -1;
1130                                 }
1131                                 SKIP_CACHE(re, &s->gb, 1);
1132
1133                                 level = SHOW_SBITS(re, &s->gb, 12);
1134                                 SKIP_CACHE(re, &s->gb, 12);
1135
1136                                 if (SHOW_UBITS(re, &s->gb, 1) == 0) {
1137                                     av_log(s->avctx, AV_LOG_ERROR,
1138                                            "2. marker bit missing in 3. esc\n");
1139                                     if (!(s->avctx->err_recognition & AV_EF_IGNORE_ERR))
1140                                         return -1;
1141                                 }
1142
1143                                 SKIP_COUNTER(re, &s->gb, 1 + 12 + 1);
1144                             }
1145
1146 #if 0
1147                             if (s->error_recognition >= FF_ER_COMPLIANT) {
1148                                 const int abs_level= FFABS(level);
1149                                 if (abs_level<=MAX_LEVEL && run<=MAX_RUN) {
1150                                     const int run1= run - rl->max_run[last][abs_level] - 1;
1151                                     if (abs_level <= rl->max_level[last][run]) {
1152                                         av_log(s->avctx, AV_LOG_ERROR, "illegal 3. esc, vlc encoding possible\n");
1153                                         return -1;
1154                                     }
1155                                     if (s->error_recognition > FF_ER_COMPLIANT) {
1156                                         if (abs_level <= rl->max_level[last][run]*2) {
1157                                             av_log(s->avctx, AV_LOG_ERROR, "illegal 3. esc, esc 1 encoding possible\n");
1158                                             return -1;
1159                                         }
1160                                         if (run1 >= 0 && abs_level <= rl->max_level[last][run1]) {
1161                                             av_log(s->avctx, AV_LOG_ERROR, "illegal 3. esc, esc 2 encoding possible\n");
1162                                             return -1;
1163                                         }
1164                                     }
1165                                 }
1166                             }
1167 #endif
1168                             if (level > 0)
1169                                 level = level * qmul + qadd;
1170                             else
1171                                 level = level * qmul - qadd;
1172
1173                             if ((unsigned)(level + 2048) > 4095) {
1174                                 if (s->avctx->err_recognition & (AV_EF_BITSTREAM|AV_EF_AGGRESSIVE)) {
1175                                     if (level > 2560 || level < -2560) {
1176                                         av_log(s->avctx, AV_LOG_ERROR,
1177                                                "|level| overflow in 3. esc, qp=%d\n",
1178                                                s->qscale);
1179                                         return -1;
1180                                     }
1181                                 }
1182                                 level = level < 0 ? -2048 : 2047;
1183                             }
1184
1185                             i += run + 1;
1186                             if (last)
1187                                 i += 192;
1188                         } else {
1189                             /* second escape */
1190                             SKIP_BITS(re, &s->gb, 2);
1191                             GET_RL_VLC(level, run, re, &s->gb, rl_vlc, TEX_VLC_BITS, 2, 1);
1192                             i    += run + rl->max_run[run >> 7][level / qmul] + 1;  // FIXME opt indexing
1193                             level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
1194                             LAST_SKIP_BITS(re, &s->gb, 1);
1195                         }
1196                     } else {
1197                         /* first escape */
1198                         SKIP_BITS(re, &s->gb, 1);
1199                         GET_RL_VLC(level, run, re, &s->gb, rl_vlc, TEX_VLC_BITS, 2, 1);
1200                         i    += run;
1201                         level = level + rl->max_level[run >> 7][(run - 1) & 63] * qmul;  // FIXME opt indexing
1202                         level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
1203                         LAST_SKIP_BITS(re, &s->gb, 1);
1204                     }
1205                 }
1206             } else {
1207                 i    += run;
1208                 level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
1209                 LAST_SKIP_BITS(re, &s->gb, 1);
1210             }
1211             ff_tlog(s->avctx, "dct[%d][%d] = %- 4d end?:%d\n", scan_table[i&63]&7, scan_table[i&63] >> 3, level, i>62);
1212             if (i > 62) {
1213                 i -= 192;
1214                 if (i & (~63)) {
1215                     av_log(s->avctx, AV_LOG_ERROR,
1216                            "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
1217                     return -1;
1218                 }
1219
1220                 block[scan_table[i]] = level;
1221                 break;
1222             }
1223
1224             block[scan_table[i]] = level;
1225         }
1226         CLOSE_READER(re, &s->gb);
1227     }
1228
1229 not_coded:
1230     if (intra) {
1231         if (!ctx->use_intra_dc_vlc) {
1232             block[0] = ff_mpeg4_pred_dc(s, n, block[0], &dc_pred_dir, 0);
1233
1234             i -= i >> 31;  // if (i == -1) i = 0;
1235         }
1236
1237         ff_mpeg4_pred_ac(s, block, n, dc_pred_dir);
1238         if (s->ac_pred)
1239             i = 63;  // FIXME not optimal
1240     }
1241     s->block_last_index[n] = i;
1242     return 0;
1243 }
1244
1245 /**
1246  * decode partition C of one MB.
1247  * @return <0 if an error occurred
1248  */
1249 static int mpeg4_decode_partitioned_mb(MpegEncContext *s, int16_t block[6][64])
1250 {
1251     Mpeg4DecContext *ctx = (Mpeg4DecContext *)s;
1252     int cbp, mb_type;
1253     const int xy = s->mb_x + s->mb_y * s->mb_stride;
1254
1255     mb_type = s->current_picture.mb_type[xy];
1256     cbp     = s->cbp_table[xy];
1257
1258     ctx->use_intra_dc_vlc = s->qscale < ctx->intra_dc_threshold;
1259
1260     if (s->current_picture.qscale_table[xy] != s->qscale)
1261         ff_set_qscale(s, s->current_picture.qscale_table[xy]);
1262
1263     if (s->pict_type == AV_PICTURE_TYPE_P ||
1264         s->pict_type == AV_PICTURE_TYPE_S) {
1265         int i;
1266         for (i = 0; i < 4; i++) {
1267             s->mv[0][i][0] = s->current_picture.motion_val[0][s->block_index[i]][0];
1268             s->mv[0][i][1] = s->current_picture.motion_val[0][s->block_index[i]][1];
1269         }
1270         s->mb_intra = IS_INTRA(mb_type);
1271
1272         if (IS_SKIP(mb_type)) {
1273             /* skip mb */
1274             for (i = 0; i < 6; i++)
1275                 s->block_last_index[i] = -1;
1276             s->mv_dir  = MV_DIR_FORWARD;
1277             s->mv_type = MV_TYPE_16X16;
1278             if (s->pict_type == AV_PICTURE_TYPE_S
1279                 && ctx->vol_sprite_usage == GMC_SPRITE) {
1280                 s->mcsel      = 1;
1281                 s->mb_skipped = 0;
1282             } else {
1283                 s->mcsel      = 0;
1284                 s->mb_skipped = 1;
1285             }
1286         } else if (s->mb_intra) {
1287             s->ac_pred = IS_ACPRED(s->current_picture.mb_type[xy]);
1288         } else if (!s->mb_intra) {
1289             // s->mcsel = 0;  // FIXME do we need to init that?
1290
1291             s->mv_dir = MV_DIR_FORWARD;
1292             if (IS_8X8(mb_type)) {
1293                 s->mv_type = MV_TYPE_8X8;
1294             } else {
1295                 s->mv_type = MV_TYPE_16X16;
1296             }
1297         }
1298     } else { /* I-Frame */
1299         s->mb_intra = 1;
1300         s->ac_pred  = IS_ACPRED(s->current_picture.mb_type[xy]);
1301     }
1302
1303     if (!IS_SKIP(mb_type)) {
1304         int i;
1305         s->bdsp.clear_blocks(s->block[0]);
1306         /* decode each block */
1307         for (i = 0; i < 6; i++) {
1308             if (mpeg4_decode_block(ctx, block[i], i, cbp & 32, s->mb_intra, ctx->rvlc) < 0) {
1309                 av_log(s->avctx, AV_LOG_ERROR,
1310                        "texture corrupted at %d %d %d\n",
1311                        s->mb_x, s->mb_y, s->mb_intra);
1312                 return -1;
1313             }
1314             cbp += cbp;
1315         }
1316     }
1317
1318     /* per-MB end of slice check */
1319     if (--s->mb_num_left <= 0) {
1320         if (mpeg4_is_resync(ctx))
1321             return SLICE_END;
1322         else
1323             return SLICE_NOEND;
1324     } else {
1325         if (mpeg4_is_resync(ctx)) {
1326             const int delta = s->mb_x + 1 == s->mb_width ? 2 : 1;
1327             if (s->cbp_table[xy + delta])
1328                 return SLICE_END;
1329         }
1330         return SLICE_OK;
1331     }
1332 }
1333
1334 static int mpeg4_decode_mb(MpegEncContext *s, int16_t block[6][64])
1335 {
1336     Mpeg4DecContext *ctx = (Mpeg4DecContext *)s;
1337     int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
1338     int16_t *mot_val;
1339     static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
1340     const int xy = s->mb_x + s->mb_y * s->mb_stride;
1341
1342     av_assert2(s->h263_pred);
1343
1344     if (s->pict_type == AV_PICTURE_TYPE_P ||
1345         s->pict_type == AV_PICTURE_TYPE_S) {
1346         do {
1347             if (get_bits1(&s->gb)) {
1348                 /* skip mb */
1349                 s->mb_intra = 0;
1350                 for (i = 0; i < 6; i++)
1351                     s->block_last_index[i] = -1;
1352                 s->mv_dir  = MV_DIR_FORWARD;
1353                 s->mv_type = MV_TYPE_16X16;
1354                 if (s->pict_type == AV_PICTURE_TYPE_S &&
1355                     ctx->vol_sprite_usage == GMC_SPRITE) {
1356                     s->current_picture.mb_type[xy] = MB_TYPE_SKIP  |
1357                                                      MB_TYPE_GMC   |
1358                                                      MB_TYPE_16x16 |
1359                                                      MB_TYPE_L0;
1360                     s->mcsel       = 1;
1361                     s->mv[0][0][0] = get_amv(ctx, 0);
1362                     s->mv[0][0][1] = get_amv(ctx, 1);
1363                     s->mb_skipped  = 0;
1364                 } else {
1365                     s->current_picture.mb_type[xy] = MB_TYPE_SKIP  |
1366                                                      MB_TYPE_16x16 |
1367                                                      MB_TYPE_L0;
1368                     s->mcsel       = 0;
1369                     s->mv[0][0][0] = 0;
1370                     s->mv[0][0][1] = 0;
1371                     s->mb_skipped  = 1;
1372                 }
1373                 goto end;
1374             }
1375             cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
1376             if (cbpc < 0) {
1377                 av_log(s->avctx, AV_LOG_ERROR,
1378                        "mcbpc damaged at %d %d\n", s->mb_x, s->mb_y);
1379                 return -1;
1380             }
1381         } while (cbpc == 20);
1382
1383         s->bdsp.clear_blocks(s->block[0]);
1384         dquant      = cbpc & 8;
1385         s->mb_intra = ((cbpc & 4) != 0);
1386         if (s->mb_intra)
1387             goto intra;
1388
1389         if (s->pict_type == AV_PICTURE_TYPE_S &&
1390             ctx->vol_sprite_usage == GMC_SPRITE && (cbpc & 16) == 0)
1391             s->mcsel = get_bits1(&s->gb);
1392         else
1393             s->mcsel = 0;
1394         cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1) ^ 0x0F;
1395         if (cbpy < 0) {
1396             av_log(s->avctx, AV_LOG_ERROR,
1397                    "P cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
1398             return AVERROR_INVALIDDATA;
1399         }
1400
1401         cbp = (cbpc & 3) | (cbpy << 2);
1402         if (dquant)
1403             ff_set_qscale(s, s->qscale + quant_tab[get_bits(&s->gb, 2)]);
1404         if ((!s->progressive_sequence) &&
1405             (cbp || (s->workaround_bugs & FF_BUG_XVID_ILACE)))
1406             s->interlaced_dct = get_bits1(&s->gb);
1407
1408         s->mv_dir = MV_DIR_FORWARD;
1409         if ((cbpc & 16) == 0) {
1410             if (s->mcsel) {
1411                 s->current_picture.mb_type[xy] = MB_TYPE_GMC   |
1412                                                  MB_TYPE_16x16 |
1413                                                  MB_TYPE_L0;
1414                 /* 16x16 global motion prediction */
1415                 s->mv_type     = MV_TYPE_16X16;
1416                 mx             = get_amv(ctx, 0);
1417                 my             = get_amv(ctx, 1);
1418                 s->mv[0][0][0] = mx;
1419                 s->mv[0][0][1] = my;
1420             } else if ((!s->progressive_sequence) && get_bits1(&s->gb)) {
1421                 s->current_picture.mb_type[xy] = MB_TYPE_16x8 |
1422                                                  MB_TYPE_L0   |
1423                                                  MB_TYPE_INTERLACED;
1424                 /* 16x8 field motion prediction */
1425                 s->mv_type = MV_TYPE_FIELD;
1426
1427                 s->field_select[0][0] = get_bits1(&s->gb);
1428                 s->field_select[0][1] = get_bits1(&s->gb);
1429
1430                 ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
1431
1432                 for (i = 0; i < 2; i++) {
1433                     mx = ff_h263_decode_motion(s, pred_x, s->f_code);
1434                     if (mx >= 0xffff)
1435                         return -1;
1436
1437                     my = ff_h263_decode_motion(s, pred_y / 2, s->f_code);
1438                     if (my >= 0xffff)
1439                         return -1;
1440
1441                     s->mv[0][i][0] = mx;
1442                     s->mv[0][i][1] = my;
1443                 }
1444             } else {
1445                 s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
1446                 /* 16x16 motion prediction */
1447                 s->mv_type = MV_TYPE_16X16;
1448                 ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
1449                 mx = ff_h263_decode_motion(s, pred_x, s->f_code);
1450
1451                 if (mx >= 0xffff)
1452                     return -1;
1453
1454                 my = ff_h263_decode_motion(s, pred_y, s->f_code);
1455
1456                 if (my >= 0xffff)
1457                     return -1;
1458                 s->mv[0][0][0] = mx;
1459                 s->mv[0][0][1] = my;
1460             }
1461         } else {
1462             s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
1463             s->mv_type                     = MV_TYPE_8X8;
1464             for (i = 0; i < 4; i++) {
1465                 mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
1466                 mx      = ff_h263_decode_motion(s, pred_x, s->f_code);
1467                 if (mx >= 0xffff)
1468                     return -1;
1469
1470                 my = ff_h263_decode_motion(s, pred_y, s->f_code);
1471                 if (my >= 0xffff)
1472                     return -1;
1473                 s->mv[0][i][0] = mx;
1474                 s->mv[0][i][1] = my;
1475                 mot_val[0]     = mx;
1476                 mot_val[1]     = my;
1477             }
1478         }
1479     } else if (s->pict_type == AV_PICTURE_TYPE_B) {
1480         int modb1;   // first bit of modb
1481         int modb2;   // second bit of modb
1482         int mb_type;
1483
1484         s->mb_intra = 0;  // B-frames never contain intra blocks
1485         s->mcsel    = 0;  //      ...               true gmc blocks
1486
1487         if (s->mb_x == 0) {
1488             for (i = 0; i < 2; i++) {
1489                 s->last_mv[i][0][0] =
1490                 s->last_mv[i][0][1] =
1491                 s->last_mv[i][1][0] =
1492                 s->last_mv[i][1][1] = 0;
1493             }
1494
1495             ff_thread_await_progress(&s->next_picture_ptr->tf, s->mb_y, 0);
1496         }
1497
1498         /* if we skipped it in the future P-frame than skip it now too */
1499         s->mb_skipped = s->next_picture.mbskip_table[s->mb_y * s->mb_stride + s->mb_x];  // Note, skiptab=0 if last was GMC
1500
1501         if (s->mb_skipped) {
1502             /* skip mb */
1503             for (i = 0; i < 6; i++)
1504                 s->block_last_index[i] = -1;
1505
1506             s->mv_dir      = MV_DIR_FORWARD;
1507             s->mv_type     = MV_TYPE_16X16;
1508             s->mv[0][0][0] =
1509             s->mv[0][0][1] =
1510             s->mv[1][0][0] =
1511             s->mv[1][0][1] = 0;
1512             s->current_picture.mb_type[xy] = MB_TYPE_SKIP  |
1513                                              MB_TYPE_16x16 |
1514                                              MB_TYPE_L0;
1515             goto end;
1516         }
1517
1518         modb1 = get_bits1(&s->gb);
1519         if (modb1) {
1520             // like MB_TYPE_B_DIRECT but no vectors coded
1521             mb_type = MB_TYPE_DIRECT2 | MB_TYPE_SKIP | MB_TYPE_L0L1;
1522             cbp     = 0;
1523         } else {
1524             modb2   = get_bits1(&s->gb);
1525             mb_type = get_vlc2(&s->gb, mb_type_b_vlc.table, MB_TYPE_B_VLC_BITS, 1);
1526             if (mb_type < 0) {
1527                 av_log(s->avctx, AV_LOG_ERROR, "illegal MB_type\n");
1528                 return -1;
1529             }
1530             mb_type = mb_type_b_map[mb_type];
1531             if (modb2) {
1532                 cbp = 0;
1533             } else {
1534                 s->bdsp.clear_blocks(s->block[0]);
1535                 cbp = get_bits(&s->gb, 6);
1536             }
1537
1538             if ((!IS_DIRECT(mb_type)) && cbp) {
1539                 if (get_bits1(&s->gb))
1540                     ff_set_qscale(s, s->qscale + get_bits1(&s->gb) * 4 - 2);
1541             }
1542
1543             if (!s->progressive_sequence) {
1544                 if (cbp)
1545                     s->interlaced_dct = get_bits1(&s->gb);
1546
1547                 if (!IS_DIRECT(mb_type) && get_bits1(&s->gb)) {
1548                     mb_type |= MB_TYPE_16x8 | MB_TYPE_INTERLACED;
1549                     mb_type &= ~MB_TYPE_16x16;
1550
1551                     if (USES_LIST(mb_type, 0)) {
1552                         s->field_select[0][0] = get_bits1(&s->gb);
1553                         s->field_select[0][1] = get_bits1(&s->gb);
1554                     }
1555                     if (USES_LIST(mb_type, 1)) {
1556                         s->field_select[1][0] = get_bits1(&s->gb);
1557                         s->field_select[1][1] = get_bits1(&s->gb);
1558                     }
1559                 }
1560             }
1561
1562             s->mv_dir = 0;
1563             if ((mb_type & (MB_TYPE_DIRECT2 | MB_TYPE_INTERLACED)) == 0) {
1564                 s->mv_type = MV_TYPE_16X16;
1565
1566                 if (USES_LIST(mb_type, 0)) {
1567                     s->mv_dir = MV_DIR_FORWARD;
1568
1569                     mx = ff_h263_decode_motion(s, s->last_mv[0][0][0], s->f_code);
1570                     my = ff_h263_decode_motion(s, s->last_mv[0][0][1], s->f_code);
1571                     s->last_mv[0][1][0] =
1572                     s->last_mv[0][0][0] =
1573                     s->mv[0][0][0]      = mx;
1574                     s->last_mv[0][1][1] =
1575                     s->last_mv[0][0][1] =
1576                     s->mv[0][0][1]      = my;
1577                 }
1578
1579                 if (USES_LIST(mb_type, 1)) {
1580                     s->mv_dir |= MV_DIR_BACKWARD;
1581
1582                     mx = ff_h263_decode_motion(s, s->last_mv[1][0][0], s->b_code);
1583                     my = ff_h263_decode_motion(s, s->last_mv[1][0][1], s->b_code);
1584                     s->last_mv[1][1][0] =
1585                     s->last_mv[1][0][0] =
1586                     s->mv[1][0][0]      = mx;
1587                     s->last_mv[1][1][1] =
1588                     s->last_mv[1][0][1] =
1589                     s->mv[1][0][1]      = my;
1590                 }
1591             } else if (!IS_DIRECT(mb_type)) {
1592                 s->mv_type = MV_TYPE_FIELD;
1593
1594                 if (USES_LIST(mb_type, 0)) {
1595                     s->mv_dir = MV_DIR_FORWARD;
1596
1597                     for (i = 0; i < 2; i++) {
1598                         mx = ff_h263_decode_motion(s, s->last_mv[0][i][0], s->f_code);
1599                         my = ff_h263_decode_motion(s, s->last_mv[0][i][1] / 2, s->f_code);
1600                         s->last_mv[0][i][0] =
1601                         s->mv[0][i][0]      = mx;
1602                         s->last_mv[0][i][1] = (s->mv[0][i][1] = my) * 2;
1603                     }
1604                 }
1605
1606                 if (USES_LIST(mb_type, 1)) {
1607                     s->mv_dir |= MV_DIR_BACKWARD;
1608
1609                     for (i = 0; i < 2; i++) {
1610                         mx = ff_h263_decode_motion(s, s->last_mv[1][i][0], s->b_code);
1611                         my = ff_h263_decode_motion(s, s->last_mv[1][i][1] / 2, s->b_code);
1612                         s->last_mv[1][i][0] =
1613                         s->mv[1][i][0]      = mx;
1614                         s->last_mv[1][i][1] = (s->mv[1][i][1] = my) * 2;
1615                     }
1616                 }
1617             }
1618         }
1619
1620         if (IS_DIRECT(mb_type)) {
1621             if (IS_SKIP(mb_type)) {
1622                 mx =
1623                 my = 0;
1624             } else {
1625                 mx = ff_h263_decode_motion(s, 0, 1);
1626                 my = ff_h263_decode_motion(s, 0, 1);
1627             }
1628
1629             s->mv_dir = MV_DIR_FORWARD | MV_DIR_BACKWARD | MV_DIRECT;
1630             mb_type  |= ff_mpeg4_set_direct_mv(s, mx, my);
1631         }
1632         s->current_picture.mb_type[xy] = mb_type;
1633     } else { /* I-Frame */
1634         do {
1635             cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
1636             if (cbpc < 0) {
1637                 av_log(s->avctx, AV_LOG_ERROR,
1638                        "I cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
1639                 return -1;
1640             }
1641         } while (cbpc == 8);
1642
1643         dquant = cbpc & 4;
1644         s->mb_intra = 1;
1645
1646 intra:
1647         s->ac_pred = get_bits1(&s->gb);
1648         if (s->ac_pred)
1649             s->current_picture.mb_type[xy] = MB_TYPE_INTRA | MB_TYPE_ACPRED;
1650         else
1651             s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
1652
1653         cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
1654         if (cbpy < 0) {
1655             av_log(s->avctx, AV_LOG_ERROR,
1656                    "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
1657             return -1;
1658         }
1659         cbp = (cbpc & 3) | (cbpy << 2);
1660
1661         ctx->use_intra_dc_vlc = s->qscale < ctx->intra_dc_threshold;
1662
1663         if (dquant)
1664             ff_set_qscale(s, s->qscale + quant_tab[get_bits(&s->gb, 2)]);
1665
1666         if (!s->progressive_sequence)
1667             s->interlaced_dct = get_bits1(&s->gb);
1668
1669         s->bdsp.clear_blocks(s->block[0]);
1670         /* decode each block */
1671         for (i = 0; i < 6; i++) {
1672             if (mpeg4_decode_block(ctx, block[i], i, cbp & 32, 1, 0) < 0)
1673                 return -1;
1674             cbp += cbp;
1675         }
1676         goto end;
1677     }
1678
1679     /* decode each block */
1680     for (i = 0; i < 6; i++) {
1681         if (mpeg4_decode_block(ctx, block[i], i, cbp & 32, 0, 0) < 0)
1682             return -1;
1683         cbp += cbp;
1684     }
1685
1686 end:
1687     /* per-MB end of slice check */
1688     if (s->codec_id == AV_CODEC_ID_MPEG4) {
1689         int next = mpeg4_is_resync(ctx);
1690         if (next) {
1691             if        (s->mb_x + s->mb_y*s->mb_width + 1 >  next && (s->avctx->err_recognition & AV_EF_AGGRESSIVE)) {
1692                 return -1;
1693             } else if (s->mb_x + s->mb_y*s->mb_width + 1 >= next)
1694                 return SLICE_END;
1695
1696             if (s->pict_type == AV_PICTURE_TYPE_B) {
1697                 const int delta= s->mb_x + 1 == s->mb_width ? 2 : 1;
1698                 ff_thread_await_progress(&s->next_picture_ptr->tf,
1699                                          (s->mb_x + delta >= s->mb_width)
1700                                          ? FFMIN(s->mb_y + 1, s->mb_height - 1)
1701                                          : s->mb_y, 0);
1702                 if (s->next_picture.mbskip_table[xy + delta])
1703                     return SLICE_OK;
1704             }
1705
1706             return SLICE_END;
1707         }
1708     }
1709
1710     return SLICE_OK;
1711 }
1712
1713 static int mpeg4_decode_gop_header(MpegEncContext *s, GetBitContext *gb)
1714 {
1715     int hours, minutes, seconds;
1716
1717     if (!show_bits(gb, 23)) {
1718         av_log(s->avctx, AV_LOG_WARNING, "GOP header invalid\n");
1719         return -1;
1720     }
1721
1722     hours   = get_bits(gb, 5);
1723     minutes = get_bits(gb, 6);
1724     check_marker(s->avctx, gb, "in gop_header");
1725     seconds = get_bits(gb, 6);
1726
1727     s->time_base = seconds + 60*(minutes + 60*hours);
1728
1729     skip_bits1(gb);
1730     skip_bits1(gb);
1731
1732     return 0;
1733 }
1734
1735 static int mpeg4_decode_profile_level(MpegEncContext *s, GetBitContext *gb)
1736 {
1737
1738     s->avctx->profile = get_bits(gb, 4);
1739     s->avctx->level   = get_bits(gb, 4);
1740
1741     // for Simple profile, level 0
1742     if (s->avctx->profile == 0 && s->avctx->level == 8) {
1743         s->avctx->level = 0;
1744     }
1745
1746     return 0;
1747 }
1748
1749 static int decode_vol_header(Mpeg4DecContext *ctx, GetBitContext *gb)
1750 {
1751     MpegEncContext *s = &ctx->m;
1752     int width, height, vo_ver_id;
1753
1754     /* vol header */
1755     skip_bits(gb, 1);                   /* random access */
1756     s->vo_type = get_bits(gb, 8);
1757     if (get_bits1(gb) != 0) {           /* is_ol_id */
1758         vo_ver_id = get_bits(gb, 4);    /* vo_ver_id */
1759         skip_bits(gb, 3);               /* vo_priority */
1760     } else {
1761         vo_ver_id = 1;
1762     }
1763     s->aspect_ratio_info = get_bits(gb, 4);
1764     if (s->aspect_ratio_info == FF_ASPECT_EXTENDED) {
1765         s->avctx->sample_aspect_ratio.num = get_bits(gb, 8);  // par_width
1766         s->avctx->sample_aspect_ratio.den = get_bits(gb, 8);  // par_height
1767     } else {
1768         s->avctx->sample_aspect_ratio = ff_h263_pixel_aspect[s->aspect_ratio_info];
1769     }
1770
1771     if ((ctx->vol_control_parameters = get_bits1(gb))) { /* vol control parameter */
1772         int chroma_format = get_bits(gb, 2);
1773         if (chroma_format != CHROMA_420)
1774             av_log(s->avctx, AV_LOG_ERROR, "illegal chroma format\n");
1775
1776         s->low_delay = get_bits1(gb);
1777         if (get_bits1(gb)) {    /* vbv parameters */
1778             get_bits(gb, 15);   /* first_half_bitrate */
1779             check_marker(s->avctx, gb, "after first_half_bitrate");
1780             get_bits(gb, 15);   /* latter_half_bitrate */
1781             check_marker(s->avctx, gb, "after latter_half_bitrate");
1782             get_bits(gb, 15);   /* first_half_vbv_buffer_size */
1783             check_marker(s->avctx, gb, "after first_half_vbv_buffer_size");
1784             get_bits(gb, 3);    /* latter_half_vbv_buffer_size */
1785             get_bits(gb, 11);   /* first_half_vbv_occupancy */
1786             check_marker(s->avctx, gb, "after first_half_vbv_occupancy");
1787             get_bits(gb, 15);   /* latter_half_vbv_occupancy */
1788             check_marker(s->avctx, gb, "after latter_half_vbv_occupancy");
1789         }
1790     } else {
1791         /* is setting low delay flag only once the smartest thing to do?
1792          * low delay detection will not be overridden. */
1793         if (s->picture_number == 0) {
1794             switch(s->vo_type) {
1795             case SIMPLE_VO_TYPE:
1796             case ADV_SIMPLE_VO_TYPE:
1797                 s->low_delay = 1;
1798                 break;
1799             default:
1800                 s->low_delay = 0;
1801             }
1802         }
1803     }
1804
1805     ctx->shape = get_bits(gb, 2); /* vol shape */
1806     if (ctx->shape != RECT_SHAPE)
1807         av_log(s->avctx, AV_LOG_ERROR, "only rectangular vol supported\n");
1808     if (ctx->shape == GRAY_SHAPE && vo_ver_id != 1) {
1809         av_log(s->avctx, AV_LOG_ERROR, "Gray shape not supported\n");
1810         skip_bits(gb, 4);  /* video_object_layer_shape_extension */
1811     }
1812
1813     check_marker(s->avctx, gb, "before time_increment_resolution");
1814
1815     s->avctx->framerate.num = get_bits(gb, 16);
1816     if (!s->avctx->framerate.num) {
1817         av_log(s->avctx, AV_LOG_ERROR, "framerate==0\n");
1818         return AVERROR_INVALIDDATA;
1819     }
1820
1821     ctx->time_increment_bits = av_log2(s->avctx->framerate.num - 1) + 1;
1822     if (ctx->time_increment_bits < 1)
1823         ctx->time_increment_bits = 1;
1824
1825     check_marker(s->avctx, gb, "before fixed_vop_rate");
1826
1827     if (get_bits1(gb) != 0)     /* fixed_vop_rate  */
1828         s->avctx->framerate.den = get_bits(gb, ctx->time_increment_bits);
1829     else
1830         s->avctx->framerate.den = 1;
1831
1832     s->avctx->time_base = av_inv_q(av_mul_q(s->avctx->framerate, (AVRational){s->avctx->ticks_per_frame, 1}));
1833
1834     ctx->t_frame = 0;
1835
1836     if (ctx->shape != BIN_ONLY_SHAPE) {
1837         if (ctx->shape == RECT_SHAPE) {
1838             check_marker(s->avctx, gb, "before width");
1839             width = get_bits(gb, 13);
1840             check_marker(s->avctx, gb, "before height");
1841             height = get_bits(gb, 13);
1842             check_marker(s->avctx, gb, "after height");
1843             if (width && height &&  /* they should be non zero but who knows */
1844                 !(s->width && s->codec_tag == AV_RL32("MP4S"))) {
1845                 if (s->width && s->height &&
1846                     (s->width != width || s->height != height))
1847                     s->context_reinit = 1;
1848                 s->width  = width;
1849                 s->height = height;
1850             }
1851         }
1852
1853         s->progressive_sequence  =
1854         s->progressive_frame     = get_bits1(gb) ^ 1;
1855         s->interlaced_dct        = 0;
1856         if (!get_bits1(gb) && (s->avctx->debug & FF_DEBUG_PICT_INFO))
1857             av_log(s->avctx, AV_LOG_INFO,           /* OBMC Disable */
1858                    "MPEG-4 OBMC not supported (very likely buggy encoder)\n");
1859         if (vo_ver_id == 1)
1860             ctx->vol_sprite_usage = get_bits1(gb);    /* vol_sprite_usage */
1861         else
1862             ctx->vol_sprite_usage = get_bits(gb, 2);  /* vol_sprite_usage */
1863
1864         if (ctx->vol_sprite_usage == STATIC_SPRITE)
1865             av_log(s->avctx, AV_LOG_ERROR, "Static Sprites not supported\n");
1866         if (ctx->vol_sprite_usage == STATIC_SPRITE ||
1867             ctx->vol_sprite_usage == GMC_SPRITE) {
1868             if (ctx->vol_sprite_usage == STATIC_SPRITE) {
1869                 skip_bits(gb, 13); // sprite_width
1870                 check_marker(s->avctx, gb, "after sprite_width");
1871                 skip_bits(gb, 13); // sprite_height
1872                 check_marker(s->avctx, gb, "after sprite_height");
1873                 skip_bits(gb, 13); // sprite_left
1874                 check_marker(s->avctx, gb, "after sprite_left");
1875                 skip_bits(gb, 13); // sprite_top
1876                 check_marker(s->avctx, gb, "after sprite_top");
1877             }
1878             ctx->num_sprite_warping_points = get_bits(gb, 6);
1879             if (ctx->num_sprite_warping_points > 3) {
1880                 av_log(s->avctx, AV_LOG_ERROR,
1881                        "%d sprite_warping_points\n",
1882                        ctx->num_sprite_warping_points);
1883                 ctx->num_sprite_warping_points = 0;
1884                 return AVERROR_INVALIDDATA;
1885             }
1886             s->sprite_warping_accuracy  = get_bits(gb, 2);
1887             ctx->sprite_brightness_change = get_bits1(gb);
1888             if (ctx->vol_sprite_usage == STATIC_SPRITE)
1889                 skip_bits1(gb); // low_latency_sprite
1890         }
1891         // FIXME sadct disable bit if verid!=1 && shape not rect
1892
1893         if (get_bits1(gb) == 1) {                   /* not_8_bit */
1894             s->quant_precision = get_bits(gb, 4);   /* quant_precision */
1895             if (get_bits(gb, 4) != 8)               /* bits_per_pixel */
1896                 av_log(s->avctx, AV_LOG_ERROR, "N-bit not supported\n");
1897             if (s->quant_precision != 5)
1898                 av_log(s->avctx, AV_LOG_ERROR,
1899                        "quant precision %d\n", s->quant_precision);
1900             if (s->quant_precision<3 || s->quant_precision>9) {
1901                 s->quant_precision = 5;
1902             }
1903         } else {
1904             s->quant_precision = 5;
1905         }
1906
1907         // FIXME a bunch of grayscale shape things
1908
1909         if ((s->mpeg_quant = get_bits1(gb))) { /* vol_quant_type */
1910             int i, v;
1911
1912             /* load default matrixes */
1913             for (i = 0; i < 64; i++) {
1914                 int j = s->idsp.idct_permutation[i];
1915                 v = ff_mpeg4_default_intra_matrix[i];
1916                 s->intra_matrix[j]        = v;
1917                 s->chroma_intra_matrix[j] = v;
1918
1919                 v = ff_mpeg4_default_non_intra_matrix[i];
1920                 s->inter_matrix[j]        = v;
1921                 s->chroma_inter_matrix[j] = v;
1922             }
1923
1924             /* load custom intra matrix */
1925             if (get_bits1(gb)) {
1926                 int last = 0;
1927                 for (i = 0; i < 64; i++) {
1928                     int j;
1929                     if (get_bits_left(gb) < 8) {
1930                         av_log(s->avctx, AV_LOG_ERROR, "insufficient data for custom matrix\n");
1931                         return AVERROR_INVALIDDATA;
1932                     }
1933                     v = get_bits(gb, 8);
1934                     if (v == 0)
1935                         break;
1936
1937                     last = v;
1938                     j = s->idsp.idct_permutation[ff_zigzag_direct[i]];
1939                     s->intra_matrix[j]        = last;
1940                     s->chroma_intra_matrix[j] = last;
1941                 }
1942
1943                 /* replicate last value */
1944                 for (; i < 64; i++) {
1945                     int j = s->idsp.idct_permutation[ff_zigzag_direct[i]];
1946                     s->intra_matrix[j]        = last;
1947                     s->chroma_intra_matrix[j] = last;
1948                 }
1949             }
1950
1951             /* load custom non intra matrix */
1952             if (get_bits1(gb)) {
1953                 int last = 0;
1954                 for (i = 0; i < 64; i++) {
1955                     int j;
1956                     if (get_bits_left(gb) < 8) {
1957                         av_log(s->avctx, AV_LOG_ERROR, "insufficient data for custom matrix\n");
1958                         return AVERROR_INVALIDDATA;
1959                     }
1960                     v = get_bits(gb, 8);
1961                     if (v == 0)
1962                         break;
1963
1964                     last = v;
1965                     j = s->idsp.idct_permutation[ff_zigzag_direct[i]];
1966                     s->inter_matrix[j]        = v;
1967                     s->chroma_inter_matrix[j] = v;
1968                 }
1969
1970                 /* replicate last value */
1971                 for (; i < 64; i++) {
1972                     int j = s->idsp.idct_permutation[ff_zigzag_direct[i]];
1973                     s->inter_matrix[j]        = last;
1974                     s->chroma_inter_matrix[j] = last;
1975                 }
1976             }
1977
1978             // FIXME a bunch of grayscale shape things
1979         }
1980
1981         if (vo_ver_id != 1)
1982             s->quarter_sample = get_bits1(gb);
1983         else
1984             s->quarter_sample = 0;
1985
1986         if (get_bits_left(gb) < 4) {
1987             av_log(s->avctx, AV_LOG_ERROR, "VOL Header truncated\n");
1988             return AVERROR_INVALIDDATA;
1989         }
1990
1991         if (!get_bits1(gb)) {
1992             int pos               = get_bits_count(gb);
1993             int estimation_method = get_bits(gb, 2);
1994             if (estimation_method < 2) {
1995                 if (!get_bits1(gb)) {
1996                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* opaque */
1997                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* transparent */
1998                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* intra_cae */
1999                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* inter_cae */
2000                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* no_update */
2001                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* upsampling */
2002                 }
2003                 if (!get_bits1(gb)) {
2004                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* intra_blocks */
2005                     ctx->cplx_estimation_trash_p += 8 * get_bits1(gb);  /* inter_blocks */
2006                     ctx->cplx_estimation_trash_p += 8 * get_bits1(gb);  /* inter4v_blocks */
2007                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* not coded blocks */
2008                 }
2009                 if (!check_marker(s->avctx, gb, "in complexity estimation part 1")) {
2010                     skip_bits_long(gb, pos - get_bits_count(gb));
2011                     goto no_cplx_est;
2012                 }
2013                 if (!get_bits1(gb)) {
2014                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* dct_coeffs */
2015                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* dct_lines */
2016                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* vlc_syms */
2017                     ctx->cplx_estimation_trash_i += 4 * get_bits1(gb);  /* vlc_bits */
2018                 }
2019                 if (!get_bits1(gb)) {
2020                     ctx->cplx_estimation_trash_p += 8 * get_bits1(gb);  /* apm */
2021                     ctx->cplx_estimation_trash_p += 8 * get_bits1(gb);  /* npm */
2022                     ctx->cplx_estimation_trash_b += 8 * get_bits1(gb);  /* interpolate_mc_q */
2023                     ctx->cplx_estimation_trash_p += 8 * get_bits1(gb);  /* forwback_mc_q */
2024                     ctx->cplx_estimation_trash_p += 8 * get_bits1(gb);  /* halfpel2 */
2025                     ctx->cplx_estimation_trash_p += 8 * get_bits1(gb);  /* halfpel4 */
2026                 }
2027                 if (!check_marker(s->avctx, gb, "in complexity estimation part 2")) {
2028                     skip_bits_long(gb, pos - get_bits_count(gb));
2029                     goto no_cplx_est;
2030                 }
2031                 if (estimation_method == 1) {
2032                     ctx->cplx_estimation_trash_i += 8 * get_bits1(gb);  /* sadct */
2033                     ctx->cplx_estimation_trash_p += 8 * get_bits1(gb);  /* qpel */
2034                 }
2035             } else
2036                 av_log(s->avctx, AV_LOG_ERROR,
2037                        "Invalid Complexity estimation method %d\n",
2038                        estimation_method);
2039         } else {
2040
2041 no_cplx_est:
2042             ctx->cplx_estimation_trash_i =
2043             ctx->cplx_estimation_trash_p =
2044             ctx->cplx_estimation_trash_b = 0;
2045         }
2046
2047         ctx->resync_marker = !get_bits1(gb); /* resync_marker_disabled */
2048
2049         s->data_partitioning = get_bits1(gb);
2050         if (s->data_partitioning)
2051             ctx->rvlc = get_bits1(gb);
2052
2053         if (vo_ver_id != 1) {
2054             ctx->new_pred = get_bits1(gb);
2055             if (ctx->new_pred) {
2056                 av_log(s->avctx, AV_LOG_ERROR, "new pred not supported\n");
2057                 skip_bits(gb, 2); /* requested upstream message type */
2058                 skip_bits1(gb);   /* newpred segment type */
2059             }
2060             if (get_bits1(gb)) // reduced_res_vop
2061                 av_log(s->avctx, AV_LOG_ERROR,
2062                        "reduced resolution VOP not supported\n");
2063         } else {
2064             ctx->new_pred = 0;
2065         }
2066
2067         ctx->scalability = get_bits1(gb);
2068
2069         if (ctx->scalability) {
2070             GetBitContext bak = *gb;
2071             int h_sampling_factor_n;
2072             int h_sampling_factor_m;
2073             int v_sampling_factor_n;
2074             int v_sampling_factor_m;
2075
2076             skip_bits1(gb);    // hierarchy_type
2077             skip_bits(gb, 4);  /* ref_layer_id */
2078             skip_bits1(gb);    /* ref_layer_sampling_dir */
2079             h_sampling_factor_n = get_bits(gb, 5);
2080             h_sampling_factor_m = get_bits(gb, 5);
2081             v_sampling_factor_n = get_bits(gb, 5);
2082             v_sampling_factor_m = get_bits(gb, 5);
2083             ctx->enhancement_type = get_bits1(gb);
2084
2085             if (h_sampling_factor_n == 0 || h_sampling_factor_m == 0 ||
2086                 v_sampling_factor_n == 0 || v_sampling_factor_m == 0) {
2087                 /* illegal scalability header (VERY broken encoder),
2088                  * trying to workaround */
2089                 ctx->scalability = 0;
2090                 *gb            = bak;
2091             } else
2092                 av_log(s->avctx, AV_LOG_ERROR, "scalability not supported\n");
2093
2094             // bin shape stuff FIXME
2095         }
2096     }
2097
2098     if (s->avctx->debug&FF_DEBUG_PICT_INFO) {
2099         av_log(s->avctx, AV_LOG_DEBUG, "tb %d/%d, tincrbits:%d, qp_prec:%d, ps:%d, low_delay:%d  %s%s%s%s\n",
2100                s->avctx->framerate.den, s->avctx->framerate.num,
2101                ctx->time_increment_bits,
2102                s->quant_precision,
2103                s->progressive_sequence,
2104                s->low_delay,
2105                ctx->scalability ? "scalability " :"" , s->quarter_sample ? "qpel " : "",
2106                s->data_partitioning ? "partition " : "", ctx->rvlc ? "rvlc " : ""
2107         );
2108     }
2109
2110     return 0;
2111 }
2112
2113 /**
2114  * Decode the user data stuff in the header.
2115  * Also initializes divx/xvid/lavc_version/build.
2116  */
2117 static int decode_user_data(Mpeg4DecContext *ctx, GetBitContext *gb)
2118 {
2119     MpegEncContext *s = &ctx->m;
2120     char buf[256];
2121     int i;
2122     int e;
2123     int ver = 0, build = 0, ver2 = 0, ver3 = 0;
2124     char last;
2125
2126     for (i = 0; i < 255 && get_bits_count(gb) < gb->size_in_bits; i++) {
2127         if (show_bits(gb, 23) == 0)
2128             break;
2129         buf[i] = get_bits(gb, 8);
2130     }
2131     buf[i] = 0;
2132
2133     /* divx detection */
2134     e = sscanf(buf, "DivX%dBuild%d%c", &ver, &build, &last);
2135     if (e < 2)
2136         e = sscanf(buf, "DivX%db%d%c", &ver, &build, &last);
2137     if (e >= 2) {
2138         ctx->divx_version = ver;
2139         ctx->divx_build   = build;
2140         s->divx_packed  = e == 3 && last == 'p';
2141     }
2142
2143     /* libavcodec detection */
2144     e = sscanf(buf, "FFmpe%*[^b]b%d", &build) + 3;
2145     if (e != 4)
2146         e = sscanf(buf, "FFmpeg v%d.%d.%d / libavcodec build: %d", &ver, &ver2, &ver3, &build);
2147     if (e != 4) {
2148         e = sscanf(buf, "Lavc%d.%d.%d", &ver, &ver2, &ver3) + 1;
2149         if (e > 1)
2150             build = (ver << 16) + (ver2 << 8) + ver3;
2151     }
2152     if (e != 4) {
2153         if (strcmp(buf, "ffmpeg") == 0)
2154             ctx->lavc_build = 4600;
2155     }
2156     if (e == 4)
2157         ctx->lavc_build = build;
2158
2159     /* Xvid detection */
2160     e = sscanf(buf, "XviD%d", &build);
2161     if (e == 1)
2162         ctx->xvid_build = build;
2163
2164     return 0;
2165 }
2166
2167 int ff_mpeg4_workaround_bugs(AVCodecContext *avctx)
2168 {
2169     Mpeg4DecContext *ctx = avctx->priv_data;
2170     MpegEncContext *s = &ctx->m;
2171
2172     if (ctx->xvid_build == -1 && ctx->divx_version == -1 && ctx->lavc_build == -1) {
2173         if (s->codec_tag        == AV_RL32("XVID") ||
2174             s->codec_tag        == AV_RL32("XVIX") ||
2175             s->codec_tag        == AV_RL32("RMP4") ||
2176             s->codec_tag        == AV_RL32("ZMP4") ||
2177             s->codec_tag        == AV_RL32("SIPP"))
2178             ctx->xvid_build = 0;
2179     }
2180
2181     if (ctx->xvid_build == -1 && ctx->divx_version == -1 && ctx->lavc_build == -1)
2182         if (s->codec_tag == AV_RL32("DIVX") && s->vo_type == 0 &&
2183             ctx->vol_control_parameters == 0)
2184             ctx->divx_version = 400;  // divx 4
2185
2186     if (ctx->xvid_build >= 0 && ctx->divx_version >= 0) {
2187         ctx->divx_version =
2188         ctx->divx_build   = -1;
2189     }
2190
2191     if (s->workaround_bugs & FF_BUG_AUTODETECT) {
2192         if (s->codec_tag == AV_RL32("XVIX"))
2193             s->workaround_bugs |= FF_BUG_XVID_ILACE;
2194
2195         if (s->codec_tag == AV_RL32("UMP4"))
2196             s->workaround_bugs |= FF_BUG_UMP4;
2197
2198         if (ctx->divx_version >= 500 && ctx->divx_build < 1814)
2199             s->workaround_bugs |= FF_BUG_QPEL_CHROMA;
2200
2201         if (ctx->divx_version > 502 && ctx->divx_build < 1814)
2202             s->workaround_bugs |= FF_BUG_QPEL_CHROMA2;
2203
2204         if (ctx->xvid_build <= 3U)
2205             s->padding_bug_score = 256 * 256 * 256 * 64;
2206
2207         if (ctx->xvid_build <= 1U)
2208             s->workaround_bugs |= FF_BUG_QPEL_CHROMA;
2209
2210         if (ctx->xvid_build <= 12U)
2211             s->workaround_bugs |= FF_BUG_EDGE;
2212
2213         if (ctx->xvid_build <= 32U)
2214             s->workaround_bugs |= FF_BUG_DC_CLIP;
2215
2216 #define SET_QPEL_FUNC(postfix1, postfix2)                           \
2217     s->qdsp.put_        ## postfix1 = ff_put_        ## postfix2;   \
2218     s->qdsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;   \
2219     s->qdsp.avg_        ## postfix1 = ff_avg_        ## postfix2;
2220
2221         if (ctx->lavc_build < 4653U)
2222             s->workaround_bugs |= FF_BUG_STD_QPEL;
2223
2224         if (ctx->lavc_build < 4655U)
2225             s->workaround_bugs |= FF_BUG_DIRECT_BLOCKSIZE;
2226
2227         if (ctx->lavc_build < 4670U)
2228             s->workaround_bugs |= FF_BUG_EDGE;
2229
2230         if (ctx->lavc_build <= 4712U)
2231             s->workaround_bugs |= FF_BUG_DC_CLIP;
2232
2233         if ((ctx->lavc_build&0xFF) >= 100) {
2234             if (ctx->lavc_build > 3621476 && ctx->lavc_build < 3752552 &&
2235                (ctx->lavc_build < 3752037 || ctx->lavc_build > 3752191) // 3.2.1+
2236             )
2237                 s->workaround_bugs |= FF_BUG_IEDGE;
2238         }
2239
2240         if (ctx->divx_version >= 0)
2241             s->workaround_bugs |= FF_BUG_DIRECT_BLOCKSIZE;
2242         if (ctx->divx_version == 501 && ctx->divx_build == 20020416)
2243             s->padding_bug_score = 256 * 256 * 256 * 64;
2244
2245         if (ctx->divx_version < 500U)
2246             s->workaround_bugs |= FF_BUG_EDGE;
2247
2248         if (ctx->divx_version >= 0)
2249             s->workaround_bugs |= FF_BUG_HPEL_CHROMA;
2250     }
2251
2252     if (s->workaround_bugs & FF_BUG_STD_QPEL) {
2253         SET_QPEL_FUNC(qpel_pixels_tab[0][5], qpel16_mc11_old_c)
2254         SET_QPEL_FUNC(qpel_pixels_tab[0][7], qpel16_mc31_old_c)
2255         SET_QPEL_FUNC(qpel_pixels_tab[0][9], qpel16_mc12_old_c)
2256         SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
2257         SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
2258         SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
2259
2260         SET_QPEL_FUNC(qpel_pixels_tab[1][5], qpel8_mc11_old_c)
2261         SET_QPEL_FUNC(qpel_pixels_tab[1][7], qpel8_mc31_old_c)
2262         SET_QPEL_FUNC(qpel_pixels_tab[1][9], qpel8_mc12_old_c)
2263         SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
2264         SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
2265         SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
2266     }
2267
2268     if (avctx->debug & FF_DEBUG_BUGS)
2269         av_log(s->avctx, AV_LOG_DEBUG,
2270                "bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
2271                s->workaround_bugs, ctx->lavc_build, ctx->xvid_build,
2272                ctx->divx_version, ctx->divx_build, s->divx_packed ? "p" : "");
2273
2274     if (CONFIG_MPEG4_DECODER && ctx->xvid_build >= 0 &&
2275         s->codec_id == AV_CODEC_ID_MPEG4 &&
2276         avctx->idct_algo == FF_IDCT_AUTO) {
2277         avctx->idct_algo = FF_IDCT_XVID;
2278         ff_mpv_idct_init(s);
2279         return 1;
2280     }
2281
2282     return 0;
2283 }
2284
2285 static int decode_vop_header(Mpeg4DecContext *ctx, GetBitContext *gb)
2286 {
2287     MpegEncContext *s = &ctx->m;
2288     int time_incr, time_increment;
2289     int64_t pts;
2290
2291     s->pict_type = get_bits(gb, 2) + AV_PICTURE_TYPE_I;        /* pict type: I = 0 , P = 1 */
2292     if (s->pict_type == AV_PICTURE_TYPE_B && s->low_delay &&
2293         ctx->vol_control_parameters == 0 && !(s->avctx->flags & AV_CODEC_FLAG_LOW_DELAY)) {
2294         av_log(s->avctx, AV_LOG_ERROR, "low_delay flag set incorrectly, clearing it\n");
2295         s->low_delay = 0;
2296     }
2297
2298     s->partitioned_frame = s->data_partitioning && s->pict_type != AV_PICTURE_TYPE_B;
2299     if (s->partitioned_frame)
2300         s->decode_mb = mpeg4_decode_partitioned_mb;
2301     else
2302         s->decode_mb = mpeg4_decode_mb;
2303
2304     time_incr = 0;
2305     while (get_bits1(gb) != 0)
2306         time_incr++;
2307
2308     check_marker(s->avctx, gb, "before time_increment");
2309
2310     if (ctx->time_increment_bits == 0 ||
2311         !(show_bits(gb, ctx->time_increment_bits + 1) & 1)) {
2312         av_log(s->avctx, AV_LOG_WARNING,
2313                "time_increment_bits %d is invalid in relation to the current bitstream, this is likely caused by a missing VOL header\n", ctx->time_increment_bits);
2314
2315         for (ctx->time_increment_bits = 1;
2316              ctx->time_increment_bits < 16;
2317              ctx->time_increment_bits++) {
2318             if (s->pict_type == AV_PICTURE_TYPE_P ||
2319                 (s->pict_type == AV_PICTURE_TYPE_S &&
2320                  ctx->vol_sprite_usage == GMC_SPRITE)) {
2321                 if ((show_bits(gb, ctx->time_increment_bits + 6) & 0x37) == 0x30)
2322                     break;
2323             } else if ((show_bits(gb, ctx->time_increment_bits + 5) & 0x1F) == 0x18)
2324                 break;
2325         }
2326
2327         av_log(s->avctx, AV_LOG_WARNING,
2328                "time_increment_bits set to %d bits, based on bitstream analysis\n", ctx->time_increment_bits);
2329         if (s->avctx->framerate.num && 4*s->avctx->framerate.num < 1<<ctx->time_increment_bits) {
2330             s->avctx->framerate.num = 1<<ctx->time_increment_bits;
2331             s->avctx->time_base = av_inv_q(av_mul_q(s->avctx->framerate, (AVRational){s->avctx->ticks_per_frame, 1}));
2332         }
2333     }
2334
2335     if (IS_3IV1)
2336         time_increment = get_bits1(gb);        // FIXME investigate further
2337     else
2338         time_increment = get_bits(gb, ctx->time_increment_bits);
2339
2340     if (s->pict_type != AV_PICTURE_TYPE_B) {
2341         s->last_time_base = s->time_base;
2342         s->time_base     += time_incr;
2343         s->time = s->time_base * s->avctx->framerate.num + time_increment;
2344         if (s->workaround_bugs & FF_BUG_UMP4) {
2345             if (s->time < s->last_non_b_time) {
2346                 /* header is not mpeg-4-compatible, broken encoder,
2347                  * trying to workaround */
2348                 s->time_base++;
2349                 s->time += s->avctx->framerate.num;
2350             }
2351         }
2352         s->pp_time         = s->time - s->last_non_b_time;
2353         s->last_non_b_time = s->time;
2354     } else {
2355         s->time    = (s->last_time_base + time_incr) * s->avctx->framerate.num + time_increment;
2356         s->pb_time = s->pp_time - (s->last_non_b_time - s->time);
2357         if (s->pp_time <= s->pb_time ||
2358             s->pp_time <= s->pp_time - s->pb_time ||
2359             s->pp_time <= 0) {
2360             /* messed up order, maybe after seeking? skipping current B-frame */
2361             return FRAME_SKIPPED;
2362         }
2363         ff_mpeg4_init_direct_mv(s);
2364
2365         if (ctx->t_frame == 0)
2366             ctx->t_frame = s->pb_time;
2367         if (ctx->t_frame == 0)
2368             ctx->t_frame = 1;  // 1/0 protection
2369         s->pp_field_time = (ROUNDED_DIV(s->last_non_b_time, ctx->t_frame) -
2370                             ROUNDED_DIV(s->last_non_b_time - s->pp_time, ctx->t_frame)) * 2;
2371         s->pb_field_time = (ROUNDED_DIV(s->time, ctx->t_frame) -
2372                             ROUNDED_DIV(s->last_non_b_time - s->pp_time, ctx->t_frame)) * 2;
2373         if (s->pp_field_time <= s->pb_field_time || s->pb_field_time <= 1) {
2374             s->pb_field_time = 2;
2375             s->pp_field_time = 4;
2376             if (!s->progressive_sequence)
2377                 return FRAME_SKIPPED;
2378         }
2379     }
2380
2381     if (s->avctx->framerate.den)
2382         pts = ROUNDED_DIV(s->time, s->avctx->framerate.den);
2383     else
2384         pts = AV_NOPTS_VALUE;
2385     ff_dlog(s->avctx, "MPEG4 PTS: %"PRId64"\n", pts);
2386
2387     check_marker(s->avctx, gb, "before vop_coded");
2388
2389     /* vop coded */
2390     if (get_bits1(gb) != 1) {
2391         if (s->avctx->debug & FF_DEBUG_PICT_INFO)
2392             av_log(s->avctx, AV_LOG_ERROR, "vop not coded\n");
2393         return FRAME_SKIPPED;
2394     }
2395     if (ctx->new_pred)
2396         decode_new_pred(ctx, gb);
2397
2398     if (ctx->shape != BIN_ONLY_SHAPE &&
2399                     (s->pict_type == AV_PICTURE_TYPE_P ||
2400                      (s->pict_type == AV_PICTURE_TYPE_S &&
2401                       ctx->vol_sprite_usage == GMC_SPRITE))) {
2402         /* rounding type for motion estimation */
2403         s->no_rounding = get_bits1(gb);
2404     } else {
2405         s->no_rounding = 0;
2406     }
2407     // FIXME reduced res stuff
2408
2409     if (ctx->shape != RECT_SHAPE) {
2410         if (ctx->vol_sprite_usage != 1 || s->pict_type != AV_PICTURE_TYPE_I) {
2411             skip_bits(gb, 13);  /* width */
2412             check_marker(s->avctx, gb, "after width");
2413             skip_bits(gb, 13);  /* height */
2414             check_marker(s->avctx, gb, "after height");
2415             skip_bits(gb, 13);  /* hor_spat_ref */
2416             check_marker(s->avctx, gb, "after hor_spat_ref");
2417             skip_bits(gb, 13);  /* ver_spat_ref */
2418         }
2419         skip_bits1(gb);         /* change_CR_disable */
2420
2421         if (get_bits1(gb) != 0)
2422             skip_bits(gb, 8);   /* constant_alpha_value */
2423     }
2424
2425     // FIXME complexity estimation stuff
2426
2427     if (ctx->shape != BIN_ONLY_SHAPE) {
2428         skip_bits_long(gb, ctx->cplx_estimation_trash_i);
2429         if (s->pict_type != AV_PICTURE_TYPE_I)
2430             skip_bits_long(gb, ctx->cplx_estimation_trash_p);
2431         if (s->pict_type == AV_PICTURE_TYPE_B)
2432             skip_bits_long(gb, ctx->cplx_estimation_trash_b);
2433
2434         if (get_bits_left(gb) < 3) {
2435             av_log(s->avctx, AV_LOG_ERROR, "Header truncated\n");
2436             return AVERROR_INVALIDDATA;
2437         }
2438         ctx->intra_dc_threshold = ff_mpeg4_dc_threshold[get_bits(gb, 3)];
2439         if (!s->progressive_sequence) {
2440             s->top_field_first = get_bits1(gb);
2441             s->alternate_scan  = get_bits1(gb);
2442         } else
2443             s->alternate_scan = 0;
2444     }
2445
2446     if (s->alternate_scan) {
2447         ff_init_scantable(s->idsp.idct_permutation, &s->inter_scantable,   ff_alternate_vertical_scan);
2448         ff_init_scantable(s->idsp.idct_permutation, &s->intra_scantable,   ff_alternate_vertical_scan);
2449         ff_init_scantable(s->idsp.idct_permutation, &s->intra_h_scantable, ff_alternate_vertical_scan);
2450         ff_init_scantable(s->idsp.idct_permutation, &s->intra_v_scantable, ff_alternate_vertical_scan);
2451     } else {
2452         ff_init_scantable(s->idsp.idct_permutation, &s->inter_scantable,   ff_zigzag_direct);
2453         ff_init_scantable(s->idsp.idct_permutation, &s->intra_scantable,   ff_zigzag_direct);
2454         ff_init_scantable(s->idsp.idct_permutation, &s->intra_h_scantable, ff_alternate_horizontal_scan);
2455         ff_init_scantable(s->idsp.idct_permutation, &s->intra_v_scantable, ff_alternate_vertical_scan);
2456     }
2457
2458     if (s->pict_type == AV_PICTURE_TYPE_S) {
2459         if((ctx->vol_sprite_usage == STATIC_SPRITE ||
2460             ctx->vol_sprite_usage == GMC_SPRITE)) {
2461             if (mpeg4_decode_sprite_trajectory(ctx, gb) < 0)
2462                 return AVERROR_INVALIDDATA;
2463             if (ctx->sprite_brightness_change)
2464                 av_log(s->avctx, AV_LOG_ERROR,
2465                     "sprite_brightness_change not supported\n");
2466             if (ctx->vol_sprite_usage == STATIC_SPRITE)
2467                 av_log(s->avctx, AV_LOG_ERROR, "static sprite not supported\n");
2468         } else {
2469             memset(s->sprite_offset, 0, sizeof(s->sprite_offset));
2470             memset(s->sprite_delta, 0, sizeof(s->sprite_delta));
2471         }
2472     }
2473
2474     if (ctx->shape != BIN_ONLY_SHAPE) {
2475         s->chroma_qscale = s->qscale = get_bits(gb, s->quant_precision);
2476         if (s->qscale == 0) {
2477             av_log(s->avctx, AV_LOG_ERROR,
2478                    "Error, header damaged or not MPEG-4 header (qscale=0)\n");
2479             return AVERROR_INVALIDDATA;  // makes no sense to continue, as there is nothing left from the image then
2480         }
2481
2482         if (s->pict_type != AV_PICTURE_TYPE_I) {
2483             s->f_code = get_bits(gb, 3);        /* fcode_for */
2484             if (s->f_code == 0) {
2485                 av_log(s->avctx, AV_LOG_ERROR,
2486                        "Error, header damaged or not MPEG-4 header (f_code=0)\n");
2487                 s->f_code = 1;
2488                 return AVERROR_INVALIDDATA;  // makes no sense to continue, as there is nothing left from the image then
2489             }
2490         } else
2491             s->f_code = 1;
2492
2493         if (s->pict_type == AV_PICTURE_TYPE_B) {
2494             s->b_code = get_bits(gb, 3);
2495             if (s->b_code == 0) {
2496                 av_log(s->avctx, AV_LOG_ERROR,
2497                        "Error, header damaged or not MPEG4 header (b_code=0)\n");
2498                 s->b_code=1;
2499                 return AVERROR_INVALIDDATA; // makes no sense to continue, as the MV decoding will break very quickly
2500             }
2501         } else
2502             s->b_code = 1;
2503
2504         if (s->avctx->debug & FF_DEBUG_PICT_INFO) {
2505             av_log(s->avctx, AV_LOG_DEBUG,
2506                    "qp:%d fc:%d,%d %s size:%d pro:%d alt:%d top:%d %spel part:%d resync:%d w:%d a:%d rnd:%d vot:%d%s dc:%d ce:%d/%d/%d time:%"PRId64" tincr:%d\n",
2507                    s->qscale, s->f_code, s->b_code,
2508                    s->pict_type == AV_PICTURE_TYPE_I ? "I" : (s->pict_type == AV_PICTURE_TYPE_P ? "P" : (s->pict_type == AV_PICTURE_TYPE_B ? "B" : "S")),
2509                    gb->size_in_bits,s->progressive_sequence, s->alternate_scan,
2510                    s->top_field_first, s->quarter_sample ? "q" : "h",
2511                    s->data_partitioning, ctx->resync_marker,
2512                    ctx->num_sprite_warping_points, s->sprite_warping_accuracy,
2513                    1 - s->no_rounding, s->vo_type,
2514                    ctx->vol_control_parameters ? " VOLC" : " ", ctx->intra_dc_threshold,
2515                    ctx->cplx_estimation_trash_i, ctx->cplx_estimation_trash_p,
2516                    ctx->cplx_estimation_trash_b,
2517                    s->time,
2518                    time_increment
2519                   );
2520         }
2521
2522         if (!ctx->scalability) {
2523             if (ctx->shape != RECT_SHAPE && s->pict_type != AV_PICTURE_TYPE_I)
2524                 skip_bits1(gb);  // vop shape coding type
2525         } else {
2526             if (ctx->enhancement_type) {
2527                 int load_backward_shape = get_bits1(gb);
2528                 if (load_backward_shape)
2529                     av_log(s->avctx, AV_LOG_ERROR,
2530                            "load backward shape isn't supported\n");
2531             }
2532             skip_bits(gb, 2);  // ref_select_code
2533         }
2534     }
2535     /* detect buggy encoders which don't set the low_delay flag
2536      * (divx4/xvid/opendivx). Note we cannot detect divx5 without B-frames
2537      * easily (although it's buggy too) */
2538     if (s->vo_type == 0 && ctx->vol_control_parameters == 0 &&
2539         ctx->divx_version == -1 && s->picture_number == 0) {
2540         av_log(s->avctx, AV_LOG_WARNING,
2541                "looks like this file was encoded with (divx4/(old)xvid/opendivx) -> forcing low_delay flag\n");
2542         s->low_delay = 1;
2543     }
2544
2545     s->picture_number++;  // better than pic number==0 always ;)
2546
2547     // FIXME add short header support
2548     s->y_dc_scale_table = ff_mpeg4_y_dc_scale_table;
2549     s->c_dc_scale_table = ff_mpeg4_c_dc_scale_table;
2550
2551     if (s->workaround_bugs & FF_BUG_EDGE) {
2552         s->h_edge_pos = s->width;
2553         s->v_edge_pos = s->height;
2554     }
2555     return 0;
2556 }
2557
2558 /**
2559  * Decode MPEG-4 headers.
2560  * @return <0 if no VOP found (or a damaged one)
2561  *         FRAME_SKIPPED if a not coded VOP is found
2562  *         0 if a VOP is found
2563  */
2564 int ff_mpeg4_decode_picture_header(Mpeg4DecContext *ctx, GetBitContext *gb)
2565 {
2566     MpegEncContext *s = &ctx->m;
2567     unsigned startcode, v;
2568     int ret;
2569     int vol = 0;
2570
2571     /* search next start code */
2572     align_get_bits(gb);
2573
2574     if (s->codec_tag == AV_RL32("WV1F") && show_bits(gb, 24) == 0x575630) {
2575         skip_bits(gb, 24);
2576         if (get_bits(gb, 8) == 0xF0)
2577             goto end;
2578     }
2579
2580     startcode = 0xff;
2581     for (;;) {
2582         if (get_bits_count(gb) >= gb->size_in_bits) {
2583             if (gb->size_in_bits == 8 &&
2584                 (ctx->divx_version >= 0 || ctx->xvid_build >= 0) || s->codec_tag == AV_RL32("QMP4")) {
2585                 av_log(s->avctx, AV_LOG_VERBOSE, "frame skip %d\n", gb->size_in_bits);
2586                 return FRAME_SKIPPED;  // divx bug
2587             } else
2588                 return -1;  // end of stream
2589         }
2590
2591         /* use the bits after the test */
2592         v = get_bits(gb, 8);
2593         startcode = ((startcode << 8) | v) & 0xffffffff;
2594
2595         if ((startcode & 0xFFFFFF00) != 0x100)
2596             continue;  // no startcode
2597
2598         if (s->avctx->debug & FF_DEBUG_STARTCODE) {
2599             av_log(s->avctx, AV_LOG_DEBUG, "startcode: %3X ", startcode);
2600             if (startcode <= 0x11F)
2601                 av_log(s->avctx, AV_LOG_DEBUG, "Video Object Start");
2602             else if (startcode <= 0x12F)
2603                 av_log(s->avctx, AV_LOG_DEBUG, "Video Object Layer Start");
2604             else if (startcode <= 0x13F)
2605                 av_log(s->avctx, AV_LOG_DEBUG, "Reserved");
2606             else if (startcode <= 0x15F)
2607                 av_log(s->avctx, AV_LOG_DEBUG, "FGS bp start");
2608             else if (startcode <= 0x1AF)
2609                 av_log(s->avctx, AV_LOG_DEBUG, "Reserved");
2610             else if (startcode == 0x1B0)
2611                 av_log(s->avctx, AV_LOG_DEBUG, "Visual Object Seq Start");
2612             else if (startcode == 0x1B1)
2613                 av_log(s->avctx, AV_LOG_DEBUG, "Visual Object Seq End");
2614             else if (startcode == 0x1B2)
2615                 av_log(s->avctx, AV_LOG_DEBUG, "User Data");
2616             else if (startcode == 0x1B3)
2617                 av_log(s->avctx, AV_LOG_DEBUG, "Group of VOP start");
2618             else if (startcode == 0x1B4)
2619                 av_log(s->avctx, AV_LOG_DEBUG, "Video Session Error");
2620             else if (startcode == 0x1B5)
2621                 av_log(s->avctx, AV_LOG_DEBUG, "Visual Object Start");
2622             else if (startcode == 0x1B6)
2623                 av_log(s->avctx, AV_LOG_DEBUG, "Video Object Plane start");
2624             else if (startcode == 0x1B7)
2625                 av_log(s->avctx, AV_LOG_DEBUG, "slice start");
2626             else if (startcode == 0x1B8)
2627                 av_log(s->avctx, AV_LOG_DEBUG, "extension start");
2628             else if (startcode == 0x1B9)
2629                 av_log(s->avctx, AV_LOG_DEBUG, "fgs start");
2630             else if (startcode == 0x1BA)
2631                 av_log(s->avctx, AV_LOG_DEBUG, "FBA Object start");
2632             else if (startcode == 0x1BB)
2633                 av_log(s->avctx, AV_LOG_DEBUG, "FBA Object Plane start");
2634             else if (startcode == 0x1BC)
2635                 av_log(s->avctx, AV_LOG_DEBUG, "Mesh Object start");
2636             else if (startcode == 0x1BD)
2637                 av_log(s->avctx, AV_LOG_DEBUG, "Mesh Object Plane start");
2638             else if (startcode == 0x1BE)
2639                 av_log(s->avctx, AV_LOG_DEBUG, "Still Texture Object start");
2640             else if (startcode == 0x1BF)
2641                 av_log(s->avctx, AV_LOG_DEBUG, "Texture Spatial Layer start");
2642             else if (startcode == 0x1C0)
2643                 av_log(s->avctx, AV_LOG_DEBUG, "Texture SNR Layer start");
2644             else if (startcode == 0x1C1)
2645                 av_log(s->avctx, AV_LOG_DEBUG, "Texture Tile start");
2646             else if (startcode == 0x1C2)
2647                 av_log(s->avctx, AV_LOG_DEBUG, "Texture Shape Layer start");
2648             else if (startcode == 0x1C3)
2649                 av_log(s->avctx, AV_LOG_DEBUG, "stuffing start");
2650             else if (startcode <= 0x1C5)
2651                 av_log(s->avctx, AV_LOG_DEBUG, "reserved");
2652             else if (startcode <= 0x1FF)
2653                 av_log(s->avctx, AV_LOG_DEBUG, "System start");
2654             av_log(s->avctx, AV_LOG_DEBUG, " at %d\n", get_bits_count(gb));
2655         }
2656
2657         if (startcode >= 0x120 && startcode <= 0x12F) {
2658             if (vol) {
2659                 av_log(s->avctx, AV_LOG_ERROR, "Multiple VOL headers");
2660                 return AVERROR_INVALIDDATA;
2661             }
2662             vol++;
2663             if ((ret = decode_vol_header(ctx, gb)) < 0)
2664                 return ret;
2665         } else if (startcode == USER_DATA_STARTCODE) {
2666             decode_user_data(ctx, gb);
2667         } else if (startcode == GOP_STARTCODE) {
2668             mpeg4_decode_gop_header(s, gb);
2669         } else if (startcode == VOS_STARTCODE) {
2670             mpeg4_decode_profile_level(s, gb);
2671         } else if (startcode == VOP_STARTCODE) {
2672             break;
2673         }
2674
2675         align_get_bits(gb);
2676         startcode = 0xff;
2677     }
2678
2679 end:
2680     if (s->avctx->flags & AV_CODEC_FLAG_LOW_DELAY)
2681         s->low_delay = 1;
2682     s->avctx->has_b_frames = !s->low_delay;
2683
2684     return decode_vop_header(ctx, gb);
2685 }
2686
2687 av_cold void ff_mpeg4videodec_static_init(void) {
2688     static int done = 0;
2689
2690     if (!done) {
2691         ff_rl_init(&ff_mpeg4_rl_intra, ff_mpeg4_static_rl_table_store[0]);
2692         ff_rl_init(&ff_rvlc_rl_inter, ff_mpeg4_static_rl_table_store[1]);
2693         ff_rl_init(&ff_rvlc_rl_intra, ff_mpeg4_static_rl_table_store[2]);
2694         INIT_VLC_RL(ff_mpeg4_rl_intra, 554);
2695         INIT_VLC_RL(ff_rvlc_rl_inter, 1072);
2696         INIT_VLC_RL(ff_rvlc_rl_intra, 1072);
2697         INIT_VLC_STATIC(&dc_lum, DC_VLC_BITS, 10 /* 13 */,
2698                         &ff_mpeg4_DCtab_lum[0][1], 2, 1,
2699                         &ff_mpeg4_DCtab_lum[0][0], 2, 1, 512);
2700         INIT_VLC_STATIC(&dc_chrom, DC_VLC_BITS, 10 /* 13 */,
2701                         &ff_mpeg4_DCtab_chrom[0][1], 2, 1,
2702                         &ff_mpeg4_DCtab_chrom[0][0], 2, 1, 512);
2703         INIT_VLC_STATIC(&sprite_trajectory, SPRITE_TRAJ_VLC_BITS, 15,
2704                         &ff_sprite_trajectory_tab[0][1], 4, 2,
2705                         &ff_sprite_trajectory_tab[0][0], 4, 2, 128);
2706         INIT_VLC_STATIC(&mb_type_b_vlc, MB_TYPE_B_VLC_BITS, 4,
2707                         &ff_mb_type_b_tab[0][1], 2, 1,
2708                         &ff_mb_type_b_tab[0][0], 2, 1, 16);
2709         done = 1;
2710     }
2711 }
2712
2713 int ff_mpeg4_frame_end(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
2714 {
2715     Mpeg4DecContext *ctx = avctx->priv_data;
2716     MpegEncContext    *s = &ctx->m;
2717
2718     /* divx 5.01+ bitstream reorder stuff */
2719     /* Since this clobbers the input buffer and hwaccel codecs still need the
2720      * data during hwaccel->end_frame we should not do this any earlier */
2721     if (s->divx_packed) {
2722         int current_pos     = s->gb.buffer == s->bitstream_buffer ? 0 : (get_bits_count(&s->gb) >> 3);
2723         int startcode_found = 0;
2724
2725         if (buf_size - current_pos > 7) {
2726
2727             int i;
2728             for (i = current_pos; i < buf_size - 4; i++)
2729
2730                 if (buf[i]     == 0 &&
2731                     buf[i + 1] == 0 &&
2732                     buf[i + 2] == 1 &&
2733                     buf[i + 3] == 0xB6) {
2734                     startcode_found = !(buf[i + 4] & 0x40);
2735                     break;
2736                 }
2737         }
2738
2739         if (startcode_found) {
2740             if (!ctx->showed_packed_warning) {
2741                 av_log(s->avctx, AV_LOG_INFO, "Video uses a non-standard and "
2742                        "wasteful way to store B-frames ('packed B-frames'). "
2743                        "Consider using the mpeg4_unpack_bframes bitstream filter without encoding but stream copy to fix it.\n");
2744                 ctx->showed_packed_warning = 1;
2745             }
2746             av_fast_padded_malloc(&s->bitstream_buffer,
2747                            &s->allocated_bitstream_buffer_size,
2748                            buf_size - current_pos);
2749             if (!s->bitstream_buffer) {
2750                 s->bitstream_buffer_size = 0;
2751                 return AVERROR(ENOMEM);
2752             }
2753             memcpy(s->bitstream_buffer, buf + current_pos,
2754                    buf_size - current_pos);
2755             s->bitstream_buffer_size = buf_size - current_pos;
2756         }
2757     }
2758
2759     return 0;
2760 }
2761
2762 #if HAVE_THREADS
2763 static int mpeg4_update_thread_context(AVCodecContext *dst,
2764                                        const AVCodecContext *src)
2765 {
2766     Mpeg4DecContext *s = dst->priv_data;
2767     const Mpeg4DecContext *s1 = src->priv_data;
2768     int init = s->m.context_initialized;
2769
2770     int ret = ff_mpeg_update_thread_context(dst, src);
2771
2772     if (ret < 0)
2773         return ret;
2774
2775     memcpy(((uint8_t*)s) + sizeof(MpegEncContext), ((uint8_t*)s1) + sizeof(MpegEncContext), sizeof(Mpeg4DecContext) - sizeof(MpegEncContext));
2776
2777     if (CONFIG_MPEG4_DECODER && !init && s1->xvid_build >= 0)
2778         ff_xvid_idct_init(&s->m.idsp, dst);
2779
2780     return 0;
2781 }
2782 #endif
2783
2784 static av_cold int decode_init(AVCodecContext *avctx)
2785 {
2786     Mpeg4DecContext *ctx = avctx->priv_data;
2787     MpegEncContext *s = &ctx->m;
2788     int ret;
2789
2790     ctx->divx_version =
2791     ctx->divx_build   =
2792     ctx->xvid_build   =
2793     ctx->lavc_build   = -1;
2794
2795     if ((ret = ff_h263_decode_init(avctx)) < 0)
2796         return ret;
2797
2798     ff_mpeg4videodec_static_init();
2799
2800     s->h263_pred = 1;
2801     s->low_delay = 0; /* default, might be overridden in the vol header during header parsing */
2802     s->decode_mb = mpeg4_decode_mb;
2803     ctx->time_increment_bits = 4; /* default value for broken headers */
2804
2805     avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
2806     avctx->internal->allocate_progress = 1;
2807
2808     return 0;
2809 }
2810
2811 static const AVOption mpeg4_options[] = {
2812     {"quarter_sample", "1/4 subpel MC", offsetof(MpegEncContext, quarter_sample), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, 0},
2813     {"divx_packed", "divx style packed b frames", offsetof(MpegEncContext, divx_packed), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, 0},
2814     {NULL}
2815 };
2816
2817 static const AVClass mpeg4_class = {
2818     "MPEG4 Video Decoder",
2819     av_default_item_name,
2820     mpeg4_options,
2821     LIBAVUTIL_VERSION_INT,
2822 };
2823
2824 AVCodec ff_mpeg4_decoder = {
2825     .name                  = "mpeg4",
2826     .long_name             = NULL_IF_CONFIG_SMALL("MPEG-4 part 2"),
2827     .type                  = AVMEDIA_TYPE_VIDEO,
2828     .id                    = AV_CODEC_ID_MPEG4,
2829     .priv_data_size        = sizeof(Mpeg4DecContext),
2830     .init                  = decode_init,
2831     .close                 = ff_h263_decode_end,
2832     .decode                = ff_h263_decode_frame,
2833     .capabilities          = AV_CODEC_CAP_DRAW_HORIZ_BAND | AV_CODEC_CAP_DR1 |
2834                              AV_CODEC_CAP_TRUNCATED | AV_CODEC_CAP_DELAY |
2835                              AV_CODEC_CAP_FRAME_THREADS,
2836     .caps_internal         = FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM,
2837     .flush                 = ff_mpeg_flush,
2838     .max_lowres            = 3,
2839     .pix_fmts              = ff_h263_hwaccel_pixfmt_list_420,
2840     .profiles              = NULL_IF_CONFIG_SMALL(ff_mpeg4_video_profiles),
2841     .update_thread_context = ONLY_IF_THREADS_ENABLED(mpeg4_update_thread_context),
2842     .priv_class = &mpeg4_class,
2843 };
2844
2845
2846 #if CONFIG_MPEG4_VDPAU_DECODER && FF_API_VDPAU
2847 static const AVClass mpeg4_vdpau_class = {
2848     "MPEG4 Video VDPAU Decoder",
2849     av_default_item_name,
2850     mpeg4_options,
2851     LIBAVUTIL_VERSION_INT,
2852 };
2853
2854 AVCodec ff_mpeg4_vdpau_decoder = {
2855     .name           = "mpeg4_vdpau",
2856     .long_name      = NULL_IF_CONFIG_SMALL("MPEG-4 part 2 (VDPAU)"),
2857     .type           = AVMEDIA_TYPE_VIDEO,
2858     .id             = AV_CODEC_ID_MPEG4,
2859     .priv_data_size = sizeof(Mpeg4DecContext),
2860     .init           = decode_init,
2861     .close          = ff_h263_decode_end,
2862     .decode         = ff_h263_decode_frame,
2863     .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_TRUNCATED | AV_CODEC_CAP_DELAY |
2864                       AV_CODEC_CAP_HWACCEL_VDPAU,
2865     .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_VDPAU_MPEG4,
2866                                                   AV_PIX_FMT_NONE },
2867     .priv_class     = &mpeg4_vdpau_class,
2868 };
2869 #endif