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h264_parser.c
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1 /*
2  * H.26L/H.264/AVC/JVT/14496-10/... parser
3  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * H.264 / AVC / MPEG4 part10 parser.
25  * @author Michael Niedermayer <michaelni@gmx.at>
26  */
27 
28 #define UNCHECKED_BITSTREAM_READER 1
29 
30 #include "libavutil/attributes.h"
31 #include "parser.h"
32 #include "h264data.h"
33 #include "golomb.h"
34 #include "internal.h"
35 
36 
38  int buf_size)
39 {
40  int i, j;
41  uint32_t state;
42  ParseContext *pc = &h->parse_context;
43  int next_avc= h->is_avc ? 0 : buf_size;
44 
45 // mb_addr= pc->mb_addr - 1;
46  state = pc->state;
47  if (state > 13)
48  state = 7;
49 
50  if (h->is_avc && !h->nal_length_size)
51  av_log(h->avctx, AV_LOG_ERROR, "AVC-parser: nal length size invalid\n");
52 
53  for (i = 0; i < buf_size; i++) {
54  if (i >= next_avc) {
55  int nalsize = 0;
56  i = next_avc;
57  for (j = 0; j < h->nal_length_size; j++)
58  nalsize = (nalsize << 8) | buf[i++];
59  if (nalsize <= 0 || nalsize > buf_size - i) {
60  av_log(h->avctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);
61  return buf_size;
62  }
63  next_avc = i + nalsize;
64  state = 5;
65  }
66 
67  if (state == 7) {
68  i += h->h264dsp.h264_find_start_code_candidate(buf + i, next_avc - i);
69  if (i < next_avc)
70  state = 2;
71  } else if (state <= 2) {
72  if (buf[i] == 1)
73  state ^= 5; // 2->7, 1->4, 0->5
74  else if (buf[i])
75  state = 7;
76  else
77  state >>= 1; // 2->1, 1->0, 0->0
78  } else if (state <= 5) {
79  int v = buf[i] & 0x1F;
80  if (v == 6 || v == 7 || v == 8 || v == 9) {
81  if (pc->frame_start_found) {
82  i++;
83  goto found;
84  }
85  } else if (v == 1 || v == 2 || v == 5) {
86  state += 8;
87  continue;
88  }
89  state = 7;
90  } else {
91  h->parse_history[h->parse_history_count++]= buf[i];
92  if (h->parse_history_count>3) {
93  unsigned int mb, last_mb= h->parse_last_mb;
94  GetBitContext gb;
95 
98  mb= get_ue_golomb_long(&gb);
99  last_mb= h->parse_last_mb;
100  h->parse_last_mb= mb;
101  if (pc->frame_start_found) {
102  if (mb <= last_mb)
103  goto found;
104  } else
105  pc->frame_start_found = 1;
106  state = 7;
107  }
108  }
109  }
110  pc->state = state;
111  if (h->is_avc)
112  return next_avc;
113  return END_NOT_FOUND;
114 
115 found:
116  pc->state = 7;
117  pc->frame_start_found = 0;
118  if (h->is_avc)
119  return next_avc;
120  return i - (state & 5) - 3 * (state > 7);
121 }
122 
124 {
125  H264Context *h = s->priv_data;
126 
127  h->slice_type_nos = s->pict_type & 3;
128 
130  get_ue_golomb(&h->gb); // redundant_pic_count
131 
132  if (ff_set_ref_count(h) < 0)
133  return AVERROR_INVALIDDATA;
134 
135  if (h->slice_type_nos != AV_PICTURE_TYPE_I) {
136  int list;
137  for (list = 0; list < h->list_count; list++) {
138  if (get_bits1(&h->gb)) {
139  int index;
140  for (index = 0; ; index++) {
141  unsigned int reordering_of_pic_nums_idc = get_ue_golomb_31(&h->gb);
142 
143  if (reordering_of_pic_nums_idc < 3)
144  get_ue_golomb(&h->gb);
145  else if (reordering_of_pic_nums_idc > 3) {
147  "illegal reordering_of_pic_nums_idc %d\n",
148  reordering_of_pic_nums_idc);
149  return AVERROR_INVALIDDATA;
150  } else
151  break;
152 
153  if (index >= h->ref_count[list]) {
154  av_log(h->avctx, AV_LOG_ERROR, "reference count overflow\n");
155  return AVERROR_INVALIDDATA;
156  }
157  }
158  }
159  }
160  }
161 
165 
166  if (get_bits1(&h->gb)) { // adaptive_ref_pic_marking_mode_flag
167  int i;
168  for (i = 0; i < MAX_MMCO_COUNT; i++) {
169  MMCOOpcode opcode = get_ue_golomb_31(&h->gb);
170  if (opcode > (unsigned) MMCO_LONG) {
172  "illegal memory management control operation %d\n",
173  opcode);
174  return AVERROR_INVALIDDATA;
175  }
176  if (opcode == MMCO_END)
177  return 0;
178  else if (opcode == MMCO_RESET)
179  return 1;
180 
181  if (opcode == MMCO_SHORT2UNUSED || opcode == MMCO_SHORT2LONG)
182  get_ue_golomb(&h->gb);
183  if (opcode == MMCO_SHORT2LONG || opcode == MMCO_LONG2UNUSED ||
184  opcode == MMCO_LONG || opcode == MMCO_SET_MAX_LONG)
185  get_ue_golomb_31(&h->gb);
186  }
187  }
188 
189  return 0;
190 }
191 
192 /**
193  * Parse NAL units of found picture and decode some basic information.
194  *
195  * @param s parser context.
196  * @param avctx codec context.
197  * @param buf buffer with field/frame data.
198  * @param buf_size size of the buffer.
199  */
201  AVCodecContext *avctx,
202  const uint8_t *buf, int buf_size)
203 {
204  H264Context *h = s->priv_data;
205  const uint8_t *buf_end = buf + buf_size;
206  unsigned int pps_id;
207  unsigned int slice_type;
208  int state = -1, got_reset = 0;
209  const uint8_t *ptr;
210  int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);
211  int field_poc[2];
212 
213  /* set some sane default values */
215  s->key_frame = 0;
217 
218  h->avctx = avctx;
221 
222  if (!buf_size)
223  return 0;
224 
225  for (;;) {
226  int src_length, dst_length, consumed, nalsize = 0;
227  if (h->is_avc) {
228  int i;
229  if (h->nal_length_size >= buf_end - buf) break;
230  nalsize = 0;
231  for (i = 0; i < h->nal_length_size; i++)
232  nalsize = (nalsize << 8) | *buf++;
233  if (nalsize <= 0 || nalsize > buf_end - buf) {
234  av_log(h->avctx, AV_LOG_ERROR, "AVC: nal size %d\n", nalsize);
235  break;
236  }
237  src_length = nalsize;
238  } else {
239  buf = avpriv_find_start_code(buf, buf_end, &state);
240  if (buf >= buf_end)
241  break;
242  --buf;
243  src_length = buf_end - buf;
244  }
245  switch (state & 0x1f) {
246  case NAL_SLICE:
247  case NAL_IDR_SLICE:
248  // Do not walk the whole buffer just to decode slice header
249  if ((state & 0x1f) == NAL_IDR_SLICE || ((state >> 5) & 0x3) == 0) {
250  /* IDR or disposable slice
251  * No need to decode many bytes because MMCOs shall not be present. */
252  if (src_length > 60)
253  src_length = 60;
254  } else {
255  /* To decode up to MMCOs */
256  if (src_length > 1000)
257  src_length = 1000;
258  }
259  break;
260  }
261  ptr = ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
262  if (ptr == NULL || dst_length < 0)
263  break;
264 
265  init_get_bits(&h->gb, ptr, 8 * dst_length);
266  switch (h->nal_unit_type) {
267  case NAL_SPS:
269  break;
270  case NAL_PPS:
272  break;
273  case NAL_SEI:
275  break;
276  case NAL_IDR_SLICE:
277  s->key_frame = 1;
278 
279  h->prev_frame_num = 0;
280  h->prev_frame_num_offset = 0;
281  h->prev_poc_msb =
282  h->prev_poc_lsb = 0;
283  /* fall through */
284  case NAL_SLICE:
285  get_ue_golomb_long(&h->gb); // skip first_mb_in_slice
286  slice_type = get_ue_golomb_31(&h->gb);
287  s->pict_type = golomb_to_pict_type[slice_type % 5];
288  if (h->sei_recovery_frame_cnt >= 0) {
289  /* key frame, since recovery_frame_cnt is set */
290  s->key_frame = 1;
291  }
292  pps_id = get_ue_golomb(&h->gb);
293  if (pps_id >= MAX_PPS_COUNT) {
295  "pps_id out of range\n");
296  return -1;
297  }
298  if (!h->pps_buffers[pps_id]) {
300  "non-existing PPS referenced\n");
301  return -1;
302  }
303  h->pps = *h->pps_buffers[pps_id];
304  if (!h->sps_buffers[h->pps.sps_id]) {
306  "non-existing SPS referenced\n");
307  return -1;
308  }
309  h->sps = *h->sps_buffers[h->pps.sps_id];
311 
312  if(h->sps.ref_frame_count <= 1 && h->pps.ref_count[0] <= 1 && s->pict_type == AV_PICTURE_TYPE_I)
313  s->key_frame = 1;
314 
315  avctx->profile = ff_h264_get_profile(&h->sps);
316  avctx->level = h->sps.level_idc;
317 
318  if (h->sps.frame_mbs_only_flag) {
320  } else {
321  if (get_bits1(&h->gb)) { // field_pic_flag
322  h->picture_structure = PICT_TOP_FIELD + get_bits1(&h->gb); // bottom_field_flag
323  } else {
325  }
326  }
327 
328  if (h->nal_unit_type == NAL_IDR_SLICE)
329  get_ue_golomb(&h->gb); /* idr_pic_id */
330  if (h->sps.poc_type == 0) {
331  h->poc_lsb = get_bits(&h->gb, h->sps.log2_max_poc_lsb);
332 
333  if (h->pps.pic_order_present == 1 &&
336  }
337 
338  if (h->sps.poc_type == 1 &&
340  h->delta_poc[0] = get_se_golomb(&h->gb);
341 
342  if (h->pps.pic_order_present == 1 &&
344  h->delta_poc[1] = get_se_golomb(&h->gb);
345  }
346 
347  /* Decode POC of this picture.
348  * The prev_ values needed for decoding POC of the next picture are not set here. */
349  field_poc[0] = field_poc[1] = INT_MAX;
350  ff_init_poc(h, field_poc, &s->output_picture_number);
351 
352  /* Continue parsing to check if MMCO_RESET is present.
353  * FIXME: MMCO_RESET could appear in non-first slice.
354  * Maybe, we should parse all undisposable non-IDR slice of this
355  * picture until encountering MMCO_RESET in a slice of it. */
356  if (h->nal_ref_idc && h->nal_unit_type != NAL_IDR_SLICE) {
357  got_reset = scan_mmco_reset(s);
358  if (got_reset < 0)
359  return got_reset;
360  }
361 
362  /* Set up the prev_ values for decoding POC of the next picture. */
363  h->prev_frame_num = got_reset ? 0 : h->frame_num;
364  h->prev_frame_num_offset = got_reset ? 0 : h->frame_num_offset;
365  if (h->nal_ref_idc != 0) {
366  if (!got_reset) {
367  h->prev_poc_msb = h->poc_msb;
368  h->prev_poc_lsb = h->poc_lsb;
369  } else {
370  h->prev_poc_msb = 0;
371  h->prev_poc_lsb =
372  h->picture_structure == PICT_BOTTOM_FIELD ? 0 : field_poc[0];
373  }
374  }
375 
376  if (h->sps.pic_struct_present_flag) {
377  switch (h->sei_pic_struct) {
380  s->repeat_pict = 0;
381  break;
385  s->repeat_pict = 1;
386  break;
389  s->repeat_pict = 2;
390  break;
392  s->repeat_pict = 3;
393  break;
395  s->repeat_pict = 5;
396  break;
397  default:
398  s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;
399  break;
400  }
401  } else {
402  s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;
403  }
404 
405  if (h->picture_structure == PICT_FRAME) {
407  if (h->sps.pic_struct_present_flag) {
408  switch (h->sei_pic_struct) {
412  break;
416  break;
417  default:
419  break;
420  }
421  } else {
422  if (field_poc[0] < field_poc[1])
424  else if (field_poc[0] > field_poc[1])
426  else
428  }
429  } else {
432  else
435  }
436 
437  return 0; /* no need to evaluate the rest */
438  }
439  buf += h->is_avc ? nalsize : consumed;
440  }
441  if (q264)
442  return 0;
443  /* didn't find a picture! */
444  av_log(h->avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);
445  return -1;
446 }
447 
449  AVCodecContext *avctx,
450  const uint8_t **poutbuf, int *poutbuf_size,
451  const uint8_t *buf, int buf_size)
452 {
453  H264Context *h = s->priv_data;
454  ParseContext *pc = &h->parse_context;
455  int next;
456 
457  if (!h->got_first) {
458  h->got_first = 1;
459  if (avctx->extradata_size) {
460  h->avctx = avctx;
461  // must be done like in decoder, otherwise opening the parser,
462  // letting it create extradata and then closing and opening again
463  // will cause has_b_frames to be always set.
464  // Note that estimate_timings_from_pts does exactly this.
465  if (!avctx->has_b_frames)
466  h->low_delay = 1;
468  }
469  }
470 
472  next = buf_size;
473  } else {
474  next = h264_find_frame_end(h, buf, buf_size);
475 
476  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
477  *poutbuf = NULL;
478  *poutbuf_size = 0;
479  return buf_size;
480  }
481 
482  if (next < 0 && next != END_NOT_FOUND) {
483  av_assert1(pc->last_index + next >= 0);
484  h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); // update state
485  }
486  }
487 
488  parse_nal_units(s, avctx, buf, buf_size);
489 
490  if (h->sei_cpb_removal_delay >= 0) {
494  } else {
495  s->dts_sync_point = INT_MIN;
496  s->dts_ref_dts_delta = INT_MIN;
497  s->pts_dts_delta = INT_MIN;
498  }
499 
500  if (s->flags & PARSER_FLAG_ONCE) {
502  }
503 
504  *poutbuf = buf;
505  *poutbuf_size = buf_size;
506  return next;
507 }
508 
509 static int h264_split(AVCodecContext *avctx,
510  const uint8_t *buf, int buf_size)
511 {
512  int i;
513  uint32_t state = -1;
514  int has_sps = 0;
515 
516  for (i = 0; i <= buf_size; i++) {
517  if ((state & 0xFFFFFF1F) == 0x107)
518  has_sps = 1;
519  /* if ((state&0xFFFFFF1F) == 0x101 ||
520  * (state&0xFFFFFF1F) == 0x102 ||
521  * (state&0xFFFFFF1F) == 0x105) {
522  * }
523  */
524  if ((state & 0xFFFFFF00) == 0x100 && (state & 0xFFFFFF1F) != 0x107 &&
525  (state & 0xFFFFFF1F) != 0x108 && (state & 0xFFFFFF1F) != 0x109) {
526  if (has_sps) {
527  while (i > 4 && buf[i - 5] == 0)
528  i--;
529  return i - 4;
530  }
531  }
532  if (i < buf_size)
533  state = (state << 8) | buf[i];
534  }
535  return 0;
536 }
537 
539 {
540  H264Context *h = s->priv_data;
541  ParseContext *pc = &h->parse_context;
542 
543  av_free(pc->buffer);
545 }
546 
548 {
549  H264Context *h = s->priv_data;
550  h->thread_context[0] = h;
551  h->slice_context_count = 1;
552  ff_h264dsp_init(&h->h264dsp, 8, 1);
553  return 0;
554 }
555 
558  .priv_data_size = sizeof(H264Context),
559  .parser_init = init,
560  .parser_parse = h264_parse,
561  .parser_close = close,
562  .split = h264_split,
563 };