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h263dec.c
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1 /*
2  * H.263 decoder
3  * Copyright (c) 2001 Fabrice Bellard
4  * Copyright (c) 2002-2004 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 /**
24  * @file
25  * H.263 decoder.
26  */
27 
28 #define UNCHECKED_BITSTREAM_READER 1
29 
30 #include "libavutil/cpu.h"
31 #include "avcodec.h"
32 #include "error_resilience.h"
33 #include "flv.h"
34 #include "h263.h"
35 #include "h263_parser.h"
36 #include "internal.h"
37 #include "mpeg4video.h"
38 #include "mpeg4video_parser.h"
39 #include "mpegvideo.h"
40 #include "msmpeg4.h"
41 #include "vdpau_internal.h"
42 #include "thread.h"
43 
45 {
46  MpegEncContext *s = avctx->priv_data;
47  int ret;
48 
49  s->avctx = avctx;
50  s->out_format = FMT_H263;
51  s->width = avctx->coded_width;
52  s->height = avctx->coded_height;
53  s->workaround_bugs = avctx->workaround_bugs;
54 
55  // set defaults
57  s->quant_precision = 5;
59  s->low_delay = 1;
60  if (avctx->codec->id == AV_CODEC_ID_MSS2)
61  avctx->pix_fmt = AV_PIX_FMT_YUV420P;
62  else
63  avctx->pix_fmt = avctx->get_format(avctx, avctx->codec->pix_fmts);
64  s->unrestricted_mv = 1;
65 
66  /* select sub codec */
67  switch (avctx->codec->id) {
68  case AV_CODEC_ID_H263:
69  case AV_CODEC_ID_H263P:
70  s->unrestricted_mv = 0;
72  break;
73  case AV_CODEC_ID_MPEG4:
74  break;
76  s->h263_pred = 1;
77  s->msmpeg4_version = 1;
78  break;
80  s->h263_pred = 1;
81  s->msmpeg4_version = 2;
82  break;
84  s->h263_pred = 1;
85  s->msmpeg4_version = 3;
86  break;
87  case AV_CODEC_ID_WMV1:
88  s->h263_pred = 1;
89  s->msmpeg4_version = 4;
90  break;
91  case AV_CODEC_ID_WMV2:
92  s->h263_pred = 1;
93  s->msmpeg4_version = 5;
94  break;
95  case AV_CODEC_ID_VC1:
96  case AV_CODEC_ID_WMV3:
99  case AV_CODEC_ID_MSS2:
100  s->h263_pred = 1;
101  s->msmpeg4_version = 6;
103  break;
104  case AV_CODEC_ID_H263I:
105  break;
106  case AV_CODEC_ID_FLV1:
107  s->h263_flv = 1;
108  break;
109  default:
110  av_log(avctx, AV_LOG_ERROR, "Unsupported codec %d\n",
111  avctx->codec->id);
112  return AVERROR(ENOSYS);
113  }
114  s->codec_id = avctx->codec->id;
115  avctx->hwaccel = ff_find_hwaccel(avctx);
116 
117  if (avctx->stream_codec_tag == AV_RL32("l263") && avctx->extradata_size == 56 && avctx->extradata[0] == 1)
118  s->ehc_mode = 1;
119 
120  /* for h263, we allocate the images after having read the header */
121  if (avctx->codec->id != AV_CODEC_ID_H263 &&
122  avctx->codec->id != AV_CODEC_ID_H263P &&
123  avctx->codec->id != AV_CODEC_ID_MPEG4)
124  if ((ret = ff_MPV_common_init(s)) < 0)
125  return ret;
126 
129 
130  return 0;
131 }
132 
134 {
135  MpegEncContext *s = avctx->priv_data;
136 
138  return 0;
139 }
140 
141 /**
142  * Return the number of bytes consumed for building the current frame.
143  */
144 static int get_consumed_bytes(MpegEncContext *s, int buf_size)
145 {
146  int pos = (get_bits_count(&s->gb) + 7) >> 3;
147 
148  if (s->divx_packed || s->avctx->hwaccel) {
149  /* We would have to scan through the whole buf to handle the weird
150  * reordering ... */
151  return buf_size;
152  } else if (s->flags & CODEC_FLAG_TRUNCATED) {
153  pos -= s->parse_context.last_index;
154  // padding is not really read so this might be -1
155  if (pos < 0)
156  pos = 0;
157  return pos;
158  } else {
159  // avoid infinite loops (maybe not needed...)
160  if (pos == 0)
161  pos = 1;
162  // oops ;)
163  if (pos + 10 > buf_size)
164  pos = buf_size;
165 
166  return pos;
167  }
168 }
169 
171 {
172  const int part_mask = s->partitioned_frame
173  ? (ER_AC_END | ER_AC_ERROR) : 0x7F;
174  const int mb_size = 16 >> s->avctx->lowres;
175  int ret;
176 
177  s->last_resync_gb = s->gb;
178  s->first_slice_line = 1;
179  s->resync_mb_x = s->mb_x;
180  s->resync_mb_y = s->mb_y;
181 
182  ff_set_qscale(s, s->qscale);
183 
184  if (s->avctx->hwaccel) {
185  const uint8_t *start = s->gb.buffer + get_bits_count(&s->gb) / 8;
186  ret = s->avctx->hwaccel->decode_slice(s->avctx, start, s->gb.buffer_end - start);
187  // ensure we exit decode loop
188  s->mb_y = s->mb_height;
189  return ret;
190  }
191 
192  if (s->partitioned_frame) {
193  const int qscale = s->qscale;
194 
195  if (CONFIG_MPEG4_DECODER && s->codec_id == AV_CODEC_ID_MPEG4)
196  if ((ret = ff_mpeg4_decode_partitions(s->avctx->priv_data)) < 0)
197  return ret;
198 
199  /* restore variables which were modified */
200  s->first_slice_line = 1;
201  s->mb_x = s->resync_mb_x;
202  s->mb_y = s->resync_mb_y;
203  ff_set_qscale(s, qscale);
204  }
205 
206  for (; s->mb_y < s->mb_height; s->mb_y++) {
207  /* per-row end of slice checks */
208  if (s->msmpeg4_version) {
209  if (s->resync_mb_y + s->slice_height == s->mb_y) {
211  s->mb_x - 1, s->mb_y, ER_MB_END);
212 
213  return 0;
214  }
215  }
216 
217  if (s->msmpeg4_version == 1) {
218  s->last_dc[0] =
219  s->last_dc[1] =
220  s->last_dc[2] = 128;
221  }
222 
224  for (; s->mb_x < s->mb_width; s->mb_x++) {
225  int ret;
226 
228 
229  if (s->resync_mb_x == s->mb_x && s->resync_mb_y + 1 == s->mb_y)
230  s->first_slice_line = 0;
231 
232  /* DCT & quantize */
233 
234  s->mv_dir = MV_DIR_FORWARD;
235  s->mv_type = MV_TYPE_16X16;
236  av_dlog(s, "%d %d %06X\n",
237  ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
238  ret = s->decode_mb(s, s->block);
239 
240  if (s->pict_type != AV_PICTURE_TYPE_B)
242 
243  if (ret < 0) {
244  const int xy = s->mb_x + s->mb_y * s->mb_stride;
245  if (ret == SLICE_END) {
246  ff_MPV_decode_mb(s, s->block);
247  if (s->loop_filter)
249 
251  s->mb_x, s->mb_y, ER_MB_END & part_mask);
252 
253  s->padding_bug_score--;
254 
255  if (++s->mb_x >= s->mb_width) {
256  s->mb_x = 0;
257  ff_mpeg_draw_horiz_band(s, s->mb_y * mb_size, mb_size);
259  s->mb_y++;
260  }
261  return 0;
262  } else if (ret == SLICE_NOEND) {
264  "Slice mismatch at MB: %d\n", xy);
266  s->mb_x + 1, s->mb_y,
267  ER_MB_END & part_mask);
268  return AVERROR_INVALIDDATA;
269  }
270  av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
272  s->mb_x, s->mb_y, ER_MB_ERROR & part_mask);
273 
274  return AVERROR_INVALIDDATA;
275  }
276 
277  ff_MPV_decode_mb(s, s->block);
278  if (s->loop_filter)
280  }
281 
282  ff_mpeg_draw_horiz_band(s, s->mb_y * mb_size, mb_size);
284 
285  s->mb_x = 0;
286  }
287 
288  av_assert1(s->mb_x == 0 && s->mb_y == s->mb_height);
289 
290  if (s->codec_id == AV_CODEC_ID_MPEG4 &&
292  get_bits_left(&s->gb) >= 48 &&
293  show_bits(&s->gb, 24) == 0x4010 &&
294  !s->data_partitioning)
295  s->padding_bug_score += 32;
296 
297  /* try to detect the padding bug */
298  if (s->codec_id == AV_CODEC_ID_MPEG4 &&
300  get_bits_left(&s->gb) >= 0 &&
301  get_bits_left(&s->gb) < 137 &&
302  !s->data_partitioning) {
303  const int bits_count = get_bits_count(&s->gb);
304  const int bits_left = s->gb.size_in_bits - bits_count;
305 
306  if (bits_left == 0) {
307  s->padding_bug_score += 16;
308  } else if (bits_left != 1) {
309  int v = show_bits(&s->gb, 8);
310  v |= 0x7F >> (7 - (bits_count & 7));
311 
312  if (v == 0x7F && bits_left <= 8)
313  s->padding_bug_score--;
314  else if (v == 0x7F && ((get_bits_count(&s->gb) + 8) & 8) &&
315  bits_left <= 16)
316  s->padding_bug_score += 4;
317  else
318  s->padding_bug_score++;
319  }
320  }
321 
323  if (s->padding_bug_score > -2 && !s->data_partitioning)
325  else
327  }
328 
329  // handle formats which don't have unique end markers
330  if (s->msmpeg4_version || (s->workaround_bugs & FF_BUG_NO_PADDING)) { // FIXME perhaps solve this more cleanly
331  int left = get_bits_left(&s->gb);
332  int max_extra = 7;
333 
334  /* no markers in M$ crap */
336  max_extra += 17;
337 
338  /* buggy padding but the frame should still end approximately at
339  * the bitstream end */
340  if ((s->workaround_bugs & FF_BUG_NO_PADDING) &&
342  max_extra += 48;
343  else if ((s->workaround_bugs & FF_BUG_NO_PADDING))
344  max_extra += 256 * 256 * 256 * 64;
345 
346  if (left > max_extra)
348  "discarding %d junk bits at end, next would be %X\n",
349  left, show_bits(&s->gb, 24));
350  else if (left < 0)
351  av_log(s->avctx, AV_LOG_ERROR, "overreading %d bits\n", -left);
352  else
354  s->mb_x - 1, s->mb_y, ER_MB_END);
355 
356  return 0;
357  }
358 
360  "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
361  get_bits_left(&s->gb), show_bits(&s->gb, 24), s->padding_bug_score);
362 
363  ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y,
364  ER_MB_END & part_mask);
365 
366  return AVERROR_INVALIDDATA;
367 }
368 
369 int ff_h263_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
370  AVPacket *avpkt)
371 {
372  const uint8_t *buf = avpkt->data;
373  int buf_size = avpkt->size;
374  MpegEncContext *s = avctx->priv_data;
375  int ret;
376  int slice_ret = 0;
377  AVFrame *pict = data;
378 
379  s->flags = avctx->flags;
380  s->flags2 = avctx->flags2;
381 
382  /* no supplementary picture */
383  if (buf_size == 0) {
384  /* special case for last picture */
385  if (s->low_delay == 0 && s->next_picture_ptr) {
386  if ((ret = av_frame_ref(pict, &s->next_picture_ptr->f)) < 0)
387  return ret;
388  s->next_picture_ptr = NULL;
389 
390  *got_frame = 1;
391  }
392 
393  return 0;
394  }
395 
396  if (s->flags & CODEC_FLAG_TRUNCATED) {
397  int next;
398 
399  if (CONFIG_MPEG4_DECODER && s->codec_id == AV_CODEC_ID_MPEG4) {
400  next = ff_mpeg4_find_frame_end(&s->parse_context, buf, buf_size);
401  } else if (CONFIG_H263_DECODER && s->codec_id == AV_CODEC_ID_H263) {
402  next = ff_h263_find_frame_end(&s->parse_context, buf, buf_size);
403  } else if (CONFIG_H263P_DECODER && s->codec_id == AV_CODEC_ID_H263P) {
404  next = ff_h263_find_frame_end(&s->parse_context, buf, buf_size);
405  } else {
407  "this codec does not support truncated bitstreams\n");
408  return AVERROR(ENOSYS);
409  }
410 
411  if (ff_combine_frame(&s->parse_context, next, (const uint8_t **)&buf,
412  &buf_size) < 0)
413  return buf_size;
414  }
415 
416 retry:
417  if (s->divx_packed && s->bitstream_buffer_size) {
418  int i;
419  for(i=0; i < buf_size-3; i++) {
420  if (buf[i]==0 && buf[i+1]==0 && buf[i+2]==1) {
421  if (buf[i+3]==0xB0) {
422  av_log(s->avctx, AV_LOG_WARNING, "Discarding excessive bitstream in packed xvid\n");
423  s->bitstream_buffer_size = 0;
424  }
425  break;
426  }
427  }
428  }
429 
430  if (s->bitstream_buffer_size && (s->divx_packed || buf_size < 20)) // divx 5.01+/xvid frame reorder
431  ret = init_get_bits8(&s->gb, s->bitstream_buffer,
433  else
434  ret = init_get_bits8(&s->gb, buf, buf_size);
435 
436  s->bitstream_buffer_size = 0;
437  if (ret < 0)
438  return ret;
439 
440  if (!s->context_initialized)
441  // we need the idct permutaton for reading a custom matrix
442  if ((ret = ff_MPV_common_init(s)) < 0)
443  return ret;
444 
445  /* We need to set current_picture_ptr before reading the header,
446  * otherwise we cannot store anyting in there */
447  if (s->current_picture_ptr == NULL || s->current_picture_ptr->f.data[0]) {
448  int i = ff_find_unused_picture(s, 0);
449  if (i < 0)
450  return i;
451  s->current_picture_ptr = &s->picture[i];
452  }
453 
454  /* let's go :-) */
455  if (CONFIG_WMV2_DECODER && s->msmpeg4_version == 5) {
457  } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
459  } else if (CONFIG_MPEG4_DECODER && avctx->codec_id == AV_CODEC_ID_MPEG4) {
460  if (s->avctx->extradata_size && s->picture_number == 0) {
461  GetBitContext gb;
462 
463  if (init_get_bits8(&gb, s->avctx->extradata, s->avctx->extradata_size) >= 0 )
465  }
466  ret = ff_mpeg4_decode_picture_header(avctx->priv_data, &s->gb);
467  } else if (CONFIG_H263I_DECODER && s->codec_id == AV_CODEC_ID_H263I) {
469  } else if (CONFIG_FLV_DECODER && s->h263_flv) {
471  } else {
473  }
474 
475  if (ret < 0 || ret == FRAME_SKIPPED) {
476  if ( s->width != avctx->coded_width
477  || s->height != avctx->coded_height) {
478  av_log(s->avctx, AV_LOG_WARNING, "Reverting picture dimensions change due to header decoding failure\n");
479  s->width = avctx->coded_width;
480  s->height= avctx->coded_height;
481  }
482  }
483  if (ret == FRAME_SKIPPED)
484  return get_consumed_bytes(s, buf_size);
485 
486  /* skip if the header was thrashed */
487  if (ret < 0) {
488  av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
489  return ret;
490  }
491 
492  avctx->has_b_frames = !s->low_delay;
493 
494  if (CONFIG_MPEG4_DECODER && avctx->codec_id == AV_CODEC_ID_MPEG4) {
495  if (ff_mpeg4_workaround_bugs(avctx) == 1)
496  goto retry;
497  }
498 
499  /* After H263 & mpeg4 header decode we have the height, width,
500  * and other parameters. So then we could init the picture.
501  * FIXME: By the way H263 decoder is evolving it should have
502  * an H263EncContext */
503  if (s->width != avctx->coded_width ||
504  s->height != avctx->coded_height ||
505  s->context_reinit) {
506  /* H.263 could change picture size any time */
507  s->context_reinit = 0;
508 
509  ret = ff_set_dimensions(avctx, s->width, s->height);
510  if (ret < 0)
511  return ret;
512 
513  if ((ret = ff_MPV_common_frame_size_change(s)))
514  return ret;
515  }
516 
517  if (s->codec_id == AV_CODEC_ID_H263 ||
518  s->codec_id == AV_CODEC_ID_H263P ||
521 
522  // for skipping the frame
525 
526  /* skip B-frames if we don't have reference frames */
527  if (s->last_picture_ptr == NULL &&
528  (s->pict_type == AV_PICTURE_TYPE_B || s->droppable))
529  return get_consumed_bytes(s, buf_size);
530  if ((avctx->skip_frame >= AVDISCARD_NONREF &&
531  s->pict_type == AV_PICTURE_TYPE_B) ||
532  (avctx->skip_frame >= AVDISCARD_NONKEY &&
533  s->pict_type != AV_PICTURE_TYPE_I) ||
534  avctx->skip_frame >= AVDISCARD_ALL)
535  return get_consumed_bytes(s, buf_size);
536 
537  if (s->next_p_frame_damaged) {
538  if (s->pict_type == AV_PICTURE_TYPE_B)
539  return get_consumed_bytes(s, buf_size);
540  else
541  s->next_p_frame_damaged = 0;
542  }
543 
544  if ((!s->no_rounding) || s->pict_type == AV_PICTURE_TYPE_B) {
547  } else {
550  }
551 
552  if ((ret = ff_MPV_frame_start(s, avctx)) < 0)
553  return ret;
554 
555  if (!s->divx_packed && !avctx->hwaccel)
556  ff_thread_finish_setup(avctx);
557 
558  if (CONFIG_MPEG4_VDPAU_DECODER && (s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)) {
560  goto frame_end;
561  }
562 
563  if (avctx->hwaccel) {
564  ret = avctx->hwaccel->start_frame(avctx, s->gb.buffer,
565  s->gb.buffer_end - s->gb.buffer);
566  if (ret < 0 )
567  return ret;
568  }
569 
571 
572  /* the second part of the wmv2 header contains the MB skip bits which
573  * are stored in current_picture->mb_type which is not available before
574  * ff_MPV_frame_start() */
575  if (CONFIG_WMV2_DECODER && s->msmpeg4_version == 5) {
577  if (ret < 0)
578  return ret;
579  if (ret == 1)
580  goto frame_end;
581  }
582 
583  /* decode each macroblock */
584  s->mb_x = 0;
585  s->mb_y = 0;
586 
587  slice_ret = decode_slice(s);
588  while (s->mb_y < s->mb_height) {
589  if (s->msmpeg4_version) {
590  if (s->slice_height == 0 || s->mb_x != 0 ||
591  (s->mb_y % s->slice_height) != 0 || get_bits_left(&s->gb) < 0)
592  break;
593  } else {
594  int prev_x = s->mb_x, prev_y = s->mb_y;
595  if (ff_h263_resync(s) < 0)
596  break;
597  if (prev_y * s->mb_width + prev_x < s->mb_y * s->mb_width + s->mb_x)
598  s->er.error_occurred = 1;
599  }
600 
601  if (s->msmpeg4_version < 4 && s->h263_pred)
603 
604  if (decode_slice(s) < 0)
605  slice_ret = AVERROR_INVALIDDATA;
606  }
607 
608  if (s->msmpeg4_version && s->msmpeg4_version < 4 &&
610  if (!CONFIG_MSMPEG4_DECODER ||
611  ff_msmpeg4_decode_ext_header(s, buf_size) < 0)
613 
615 frame_end:
616  ff_er_frame_end(&s->er);
617 
618  if (avctx->hwaccel) {
619  ret = avctx->hwaccel->end_frame(avctx);
620  if (ret < 0)
621  return ret;
622  }
623 
624  ff_MPV_frame_end(s);
625 
626  if (CONFIG_MPEG4_DECODER && avctx->codec_id == AV_CODEC_ID_MPEG4)
627  ff_mpeg4_frame_end(avctx, buf, buf_size);
628 
629  if (!s->divx_packed && avctx->hwaccel)
630  ff_thread_finish_setup(avctx);
631 
634  if (s->pict_type == AV_PICTURE_TYPE_B || s->low_delay) {
635  if ((ret = av_frame_ref(pict, &s->current_picture_ptr->f)) < 0)
636  return ret;
639  } else if (s->last_picture_ptr != NULL) {
640  if ((ret = av_frame_ref(pict, &s->last_picture_ptr->f)) < 0)
641  return ret;
644  }
645 
646  if (s->last_picture_ptr || s->low_delay) {
647  if ( pict->format == AV_PIX_FMT_YUV420P
648  && (s->codec_tag == AV_RL32("GEOV") || s->codec_tag == AV_RL32("GEOX"))) {
649  int x, y, p;
651  for (p=0; p<3; p++) {
652  int w = FF_CEIL_RSHIFT(pict-> width, !!p);
653  int h = FF_CEIL_RSHIFT(pict->height, !!p);
654  int linesize = pict->linesize[p];
655  for (y=0; y<(h>>1); y++)
656  for (x=0; x<w; x++)
657  FFSWAP(int,
658  pict->data[p][x + y*linesize],
659  pict->data[p][x + (h-1-y)*linesize]);
660  }
661  }
662  *got_frame = 1;
663  }
664 
665  if (slice_ret < 0 && (avctx->err_recognition & AV_EF_EXPLODE))
666  return ret;
667  else
668  return get_consumed_bytes(s, buf_size);
669 }
670 
672 #if CONFIG_VAAPI
674 #endif
675 #if CONFIG_VDPAU
677 #endif
680 };
681 
683  .name = "h263",
684  .long_name = NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
685  .type = AVMEDIA_TYPE_VIDEO,
686  .id = AV_CODEC_ID_H263,
687  .priv_data_size = sizeof(MpegEncContext),
691  .capabilities = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 |
693  .flush = ff_mpeg_flush,
694  .max_lowres = 3,
696 };
697 
699  .name = "h263p",
700  .long_name = NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
701  .type = AVMEDIA_TYPE_VIDEO,
702  .id = AV_CODEC_ID_H263P,
703  .priv_data_size = sizeof(MpegEncContext),
707  .capabilities = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 |
709  .flush = ff_mpeg_flush,
710  .max_lowres = 3,
712 };