FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
h264_parser.c
Go to the documentation of this file.
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 #include "mpegutils.h"
36 
37 typedef struct H264ParseContext {
38  H264Context h;
39  ParseContext pc;
40  int got_first;
41 } H264ParseContext;
42 
43 
44 static int h264_find_frame_end(H264ParseContext *p, const uint8_t *buf,
45  int buf_size)
46 {
47  H264Context *h = &p->h;
48  int i, j;
49  uint32_t state;
50  ParseContext *pc = &p->pc;
51 
52  int next_avc= h->is_avc ? 0 : buf_size;
53 // mb_addr= pc->mb_addr - 1;
54  state = pc->state;
55  if (state > 13)
56  state = 7;
57 
58  if (h->is_avc && !h->nal_length_size)
59  av_log(h->avctx, AV_LOG_ERROR, "AVC-parser: nal length size invalid\n");
60 
61  for (i = 0; i < buf_size; i++) {
62  if (i >= next_avc) {
63  int nalsize = 0;
64  i = next_avc;
65  for (j = 0; j < h->nal_length_size; j++)
66  nalsize = (nalsize << 8) | buf[i++];
67  if (nalsize <= 0 || nalsize > buf_size - i) {
68  av_log(h->avctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);
69  return buf_size;
70  }
71  next_avc = i + nalsize;
72  state = 5;
73  }
74 
75  if (state == 7) {
76  i += h->h264dsp.startcode_find_candidate(buf + i, next_avc - i);
77  if (i < next_avc)
78  state = 2;
79  } else if (state <= 2) {
80  if (buf[i] == 1)
81  state ^= 5; // 2->7, 1->4, 0->5
82  else if (buf[i])
83  state = 7;
84  else
85  state >>= 1; // 2->1, 1->0, 0->0
86  } else if (state <= 5) {
87  int nalu_type = buf[i] & 0x1F;
88  if (nalu_type == NAL_SEI || nalu_type == NAL_SPS ||
89  nalu_type == NAL_PPS || nalu_type == NAL_AUD) {
90  if (pc->frame_start_found) {
91  i++;
92  goto found;
93  }
94  } else if (nalu_type == NAL_SLICE || nalu_type == NAL_DPA ||
95  nalu_type == NAL_IDR_SLICE) {
96  state += 8;
97  continue;
98  }
99  state = 7;
100  } else {
101  h->parse_history[h->parse_history_count++]= buf[i];
102  if (h->parse_history_count>5) {
103  unsigned int mb, last_mb= h->parse_last_mb;
104  GetBitContext gb;
105 
106  init_get_bits(&gb, h->parse_history, 8*h->parse_history_count);
107  h->parse_history_count=0;
108  mb= get_ue_golomb_long(&gb);
109  h->parse_last_mb= mb;
110  if (pc->frame_start_found) {
111  if (mb <= last_mb)
112  goto found;
113  } else
114  pc->frame_start_found = 1;
115  state = 7;
116  }
117  }
118  }
119  pc->state = state;
120  if (h->is_avc)
121  return next_avc;
122  return END_NOT_FOUND;
123 
124 found:
125  pc->state = 7;
126  pc->frame_start_found = 0;
127  if (h->is_avc)
128  return next_avc;
129  return i - (state & 5) - 5 * (state > 7);
130 }
131 
132 static int scan_mmco_reset(AVCodecParserContext *s)
133 {
134  H264ParseContext *p = s->priv_data;
135  H264Context *h = &p->h;
136 
137  h->slice_type_nos = s->pict_type & 3;
138 
139  if (h->pps.redundant_pic_cnt_present)
140  get_ue_golomb(&h->gb); // redundant_pic_count
141 
142  if (ff_set_ref_count(h) < 0)
143  return AVERROR_INVALIDDATA;
144 
145  if (h->slice_type_nos != AV_PICTURE_TYPE_I) {
146  int list;
147  for (list = 0; list < h->list_count; list++) {
148  if (get_bits1(&h->gb)) {
149  int index;
150  for (index = 0; ; index++) {
151  unsigned int reordering_of_pic_nums_idc = get_ue_golomb_31(&h->gb);
152 
153  if (reordering_of_pic_nums_idc < 3)
154  get_ue_golomb(&h->gb);
155  else if (reordering_of_pic_nums_idc > 3) {
156  av_log(h->avctx, AV_LOG_ERROR,
157  "illegal reordering_of_pic_nums_idc %d\n",
158  reordering_of_pic_nums_idc);
159  return AVERROR_INVALIDDATA;
160  } else
161  break;
162 
163  if (index >= h->ref_count[list]) {
164  av_log(h->avctx, AV_LOG_ERROR,
165  "reference count %d overflow\n", index);
166  return AVERROR_INVALIDDATA;
167  }
168  }
169  }
170  }
171  }
172 
173  if ((h->pps.weighted_pred && h->slice_type_nos == AV_PICTURE_TYPE_P) ||
174  (h->pps.weighted_bipred_idc == 1 && h->slice_type_nos == AV_PICTURE_TYPE_B))
175  ff_pred_weight_table(h);
176 
177  if (get_bits1(&h->gb)) { // adaptive_ref_pic_marking_mode_flag
178  int i;
179  for (i = 0; i < MAX_MMCO_COUNT; i++) {
180  MMCOOpcode opcode = get_ue_golomb_31(&h->gb);
181  if (opcode > (unsigned) MMCO_LONG) {
182  av_log(h->avctx, AV_LOG_ERROR,
183  "illegal memory management control operation %d\n",
184  opcode);
185  return AVERROR_INVALIDDATA;
186  }
187  if (opcode == MMCO_END)
188  return 0;
189  else if (opcode == MMCO_RESET)
190  return 1;
191 
192  if (opcode == MMCO_SHORT2UNUSED || opcode == MMCO_SHORT2LONG)
193  get_ue_golomb(&h->gb);
194  if (opcode == MMCO_SHORT2LONG || opcode == MMCO_LONG2UNUSED ||
195  opcode == MMCO_LONG || opcode == MMCO_SET_MAX_LONG)
196  get_ue_golomb_31(&h->gb);
197  }
198  }
199 
200  return 0;
201 }
202 
203 /**
204  * Parse NAL units of found picture and decode some basic information.
205  *
206  * @param s parser context.
207  * @param avctx codec context.
208  * @param buf buffer with field/frame data.
209  * @param buf_size size of the buffer.
210  */
211 static inline int parse_nal_units(AVCodecParserContext *s,
212  AVCodecContext *avctx,
213  const uint8_t * const buf, int buf_size)
214 {
215  H264ParseContext *p = s->priv_data;
216  H264Context *h = &p->h;
217  int buf_index, next_avc;
218  unsigned int pps_id;
219  unsigned int slice_type;
220  int state = -1, got_reset = 0;
221  const uint8_t *ptr;
222  int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);
223  int field_poc[2];
224 
225  /* set some sane default values */
226  s->pict_type = AV_PICTURE_TYPE_I;
227  s->key_frame = 0;
228  s->picture_structure = AV_PICTURE_STRUCTURE_UNKNOWN;
229 
230  h->avctx = avctx;
231  ff_h264_reset_sei(h);
232  h->sei_fpa.frame_packing_arrangement_cancel_flag = -1;
233 
234  if (!buf_size)
235  return 0;
236 
237  buf_index = 0;
238  next_avc = h->is_avc ? 0 : buf_size;
239  for (;;) {
240  int src_length, dst_length, consumed, nalsize = 0;
241 
242  if (buf_index >= next_avc) {
243  nalsize = get_avc_nalsize(h, buf, buf_size, &buf_index);
244  if (nalsize < 0)
245  break;
246  next_avc = buf_index + nalsize;
247  } else {
248  buf_index = find_start_code(buf, buf_size, buf_index, next_avc);
249  if (buf_index >= buf_size)
250  break;
251  if (buf_index >= next_avc)
252  continue;
253  }
254  src_length = next_avc - buf_index;
255 
256  state = buf[buf_index];
257  switch (state & 0x1f) {
258  case NAL_SLICE:
259  case NAL_IDR_SLICE:
260  // Do not walk the whole buffer just to decode slice header
261  if ((state & 0x1f) == NAL_IDR_SLICE || ((state >> 5) & 0x3) == 0) {
262  /* IDR or disposable slice
263  * No need to decode many bytes because MMCOs shall not be present. */
264  if (src_length > 60)
265  src_length = 60;
266  } else {
267  /* To decode up to MMCOs */
268  if (src_length > 1000)
269  src_length = 1000;
270  }
271  break;
272  }
273  ptr = ff_h264_decode_nal(h, buf + buf_index, &dst_length,
274  &consumed, src_length);
275  if (!ptr || dst_length < 0)
276  break;
277 
278  buf_index += consumed;
279 
280  init_get_bits(&h->gb, ptr, 8 * dst_length);
281  switch (h->nal_unit_type) {
282  case NAL_SPS:
283  ff_h264_decode_seq_parameter_set(h);
284  break;
285  case NAL_PPS:
286  ff_h264_decode_picture_parameter_set(h, h->gb.size_in_bits);
287  break;
288  case NAL_SEI:
289  ff_h264_decode_sei(h);
290  break;
291  case NAL_IDR_SLICE:
292  s->key_frame = 1;
293 
294  h->prev_frame_num = 0;
295  h->prev_frame_num_offset = 0;
296  h->prev_poc_msb =
297  h->prev_poc_lsb = 0;
298  /* fall through */
299  case NAL_SLICE:
300  get_ue_golomb_long(&h->gb); // skip first_mb_in_slice
301  slice_type = get_ue_golomb_31(&h->gb);
302  s->pict_type = golomb_to_pict_type[slice_type % 5];
303  if (h->sei_recovery_frame_cnt >= 0) {
304  /* key frame, since recovery_frame_cnt is set */
305  s->key_frame = 1;
306  }
307  pps_id = get_ue_golomb(&h->gb);
308  if (pps_id >= MAX_PPS_COUNT) {
309  av_log(h->avctx, AV_LOG_ERROR,
310  "pps_id %u out of range\n", pps_id);
311  return -1;
312  }
313  if (!h->pps_buffers[pps_id]) {
314  av_log(h->avctx, AV_LOG_ERROR,
315  "non-existing PPS %u referenced\n", pps_id);
316  return -1;
317  }
318  h->pps = *h->pps_buffers[pps_id];
319  if (!h->sps_buffers[h->pps.sps_id]) {
320  av_log(h->avctx, AV_LOG_ERROR,
321  "non-existing SPS %u referenced\n", h->pps.sps_id);
322  return -1;
323  }
324  h->sps = *h->sps_buffers[h->pps.sps_id];
325  h->frame_num = get_bits(&h->gb, h->sps.log2_max_frame_num);
326 
327  if(h->sps.ref_frame_count <= 1 && h->pps.ref_count[0] <= 1 && s->pict_type == AV_PICTURE_TYPE_I)
328  s->key_frame = 1;
329 
330  s->coded_width = 16 * h->sps.mb_width;
331  s->coded_height = 16 * h->sps.mb_height;
332  s->width = s->coded_width - (h->sps.crop_right + h->sps.crop_left);
333  s->height = s->coded_height - (h->sps.crop_top + h->sps.crop_bottom);
334  if (s->width <= 0 || s->height <= 0) {
335  s->width = s->coded_width;
336  s->height = s->coded_height;
337  }
338 
339  switch (h->sps.bit_depth_luma) {
340  case 9:
341  if (CHROMA444(h)) s->format = AV_PIX_FMT_YUV444P9;
342  else if (CHROMA422(h)) s->format = AV_PIX_FMT_YUV422P9;
343  else s->format = AV_PIX_FMT_YUV420P9;
344  break;
345  case 10:
346  if (CHROMA444(h)) s->format = AV_PIX_FMT_YUV444P10;
347  else if (CHROMA422(h)) s->format = AV_PIX_FMT_YUV422P10;
348  else s->format = AV_PIX_FMT_YUV420P10;
349  break;
350  case 8:
351  if (CHROMA444(h)) s->format = AV_PIX_FMT_YUV444P;
352  else if (CHROMA422(h)) s->format = AV_PIX_FMT_YUV422P;
353  else s->format = AV_PIX_FMT_YUV420P;
354  break;
355  default:
356  s->format = AV_PIX_FMT_NONE;
357  }
358 
359  avctx->profile = ff_h264_get_profile(&h->sps);
360  avctx->level = h->sps.level_idc;
361 
362  if (h->sps.frame_mbs_only_flag) {
363  h->picture_structure = PICT_FRAME;
364  } else {
365  if (get_bits1(&h->gb)) { // field_pic_flag
366  h->picture_structure = PICT_TOP_FIELD + get_bits1(&h->gb); // bottom_field_flag
367  } else {
368  h->picture_structure = PICT_FRAME;
369  }
370  }
371 
372  if (h->nal_unit_type == NAL_IDR_SLICE)
373  get_ue_golomb(&h->gb); /* idr_pic_id */
374  if (h->sps.poc_type == 0) {
375  h->poc_lsb = get_bits(&h->gb, h->sps.log2_max_poc_lsb);
376 
377  if (h->pps.pic_order_present == 1 &&
378  h->picture_structure == PICT_FRAME)
379  h->delta_poc_bottom = get_se_golomb(&h->gb);
380  }
381 
382  if (h->sps.poc_type == 1 &&
383  !h->sps.delta_pic_order_always_zero_flag) {
384  h->delta_poc[0] = get_se_golomb(&h->gb);
385 
386  if (h->pps.pic_order_present == 1 &&
387  h->picture_structure == PICT_FRAME)
388  h->delta_poc[1] = get_se_golomb(&h->gb);
389  }
390 
391  /* Decode POC of this picture.
392  * The prev_ values needed for decoding POC of the next picture are not set here. */
393  field_poc[0] = field_poc[1] = INT_MAX;
394  ff_init_poc(h, field_poc, &s->output_picture_number);
395 
396  /* Continue parsing to check if MMCO_RESET is present.
397  * FIXME: MMCO_RESET could appear in non-first slice.
398  * Maybe, we should parse all undisposable non-IDR slice of this
399  * picture until encountering MMCO_RESET in a slice of it. */
400  if (h->nal_ref_idc && h->nal_unit_type != NAL_IDR_SLICE) {
401  got_reset = scan_mmco_reset(s);
402  if (got_reset < 0)
403  return got_reset;
404  }
405 
406  /* Set up the prev_ values for decoding POC of the next picture. */
407  h->prev_frame_num = got_reset ? 0 : h->frame_num;
408  h->prev_frame_num_offset = got_reset ? 0 : h->frame_num_offset;
409  if (h->nal_ref_idc != 0) {
410  if (!got_reset) {
411  h->prev_poc_msb = h->poc_msb;
412  h->prev_poc_lsb = h->poc_lsb;
413  } else {
414  h->prev_poc_msb = 0;
415  h->prev_poc_lsb =
416  h->picture_structure == PICT_BOTTOM_FIELD ? 0 : field_poc[0];
417  }
418  }
419 
420  if (h->sps.pic_struct_present_flag) {
421  switch (h->sei_pic_struct) {
422  case SEI_PIC_STRUCT_TOP_FIELD:
423  case SEI_PIC_STRUCT_BOTTOM_FIELD:
424  s->repeat_pict = 0;
425  break;
426  case SEI_PIC_STRUCT_FRAME:
427  case SEI_PIC_STRUCT_TOP_BOTTOM:
428  case SEI_PIC_STRUCT_BOTTOM_TOP:
429  s->repeat_pict = 1;
430  break;
431  case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
432  case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
433  s->repeat_pict = 2;
434  break;
435  case SEI_PIC_STRUCT_FRAME_DOUBLING:
436  s->repeat_pict = 3;
437  break;
438  case SEI_PIC_STRUCT_FRAME_TRIPLING:
439  s->repeat_pict = 5;
440  break;
441  default:
442  s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;
443  break;
444  }
445  } else {
446  s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;
447  }
448 
449  if (h->picture_structure == PICT_FRAME) {
450  s->picture_structure = AV_PICTURE_STRUCTURE_FRAME;
451  if (h->sps.pic_struct_present_flag) {
452  switch (h->sei_pic_struct) {
453  case SEI_PIC_STRUCT_TOP_BOTTOM:
454  case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
455  s->field_order = AV_FIELD_TT;
456  break;
457  case SEI_PIC_STRUCT_BOTTOM_TOP:
458  case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
459  s->field_order = AV_FIELD_BB;
460  break;
461  default:
462  s->field_order = AV_FIELD_PROGRESSIVE;
463  break;
464  }
465  } else {
466  if (field_poc[0] < field_poc[1])
467  s->field_order = AV_FIELD_TT;
468  else if (field_poc[0] > field_poc[1])
469  s->field_order = AV_FIELD_BB;
470  else
471  s->field_order = AV_FIELD_PROGRESSIVE;
472  }
473  } else {
474  if (h->picture_structure == PICT_TOP_FIELD)
475  s->picture_structure = AV_PICTURE_STRUCTURE_TOP_FIELD;
476  else
477  s->picture_structure = AV_PICTURE_STRUCTURE_BOTTOM_FIELD;
478  s->field_order = AV_FIELD_UNKNOWN;
479  }
480 
481  return 0; /* no need to evaluate the rest */
482  }
483  }
484  if (q264)
485  return 0;
486  /* didn't find a picture! */
487  av_log(h->avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);
488  return -1;
489 }
490 
491 static int h264_parse(AVCodecParserContext *s,
492  AVCodecContext *avctx,
493  const uint8_t **poutbuf, int *poutbuf_size,
494  const uint8_t *buf, int buf_size)
495 {
496  H264ParseContext *p = s->priv_data;
497  H264Context *h = &p->h;
498  ParseContext *pc = &p->pc;
499  int next;
500 
501  if (!p->got_first) {
502  p->got_first = 1;
503  if (avctx->extradata_size) {
504  h->avctx = avctx;
505  // must be done like in decoder, otherwise opening the parser,
506  // letting it create extradata and then closing and opening again
507  // will cause has_b_frames to be always set.
508  // Note that estimate_timings_from_pts does exactly this.
509  if (!avctx->has_b_frames)
510  h->low_delay = 1;
511  ff_h264_decode_extradata(h, avctx->extradata, avctx->extradata_size);
512  }
513  }
514 
515  if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
516  next = buf_size;
517  } else {
518  next = h264_find_frame_end(p, buf, buf_size);
519 
520  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
521  *poutbuf = NULL;
522  *poutbuf_size = 0;
523  return buf_size;
524  }
525 
526  if (next < 0 && next != END_NOT_FOUND) {
527  av_assert1(pc->last_index + next >= 0);
528  h264_find_frame_end(p, &pc->buffer[pc->last_index + next], -next); // update state
529  }
530  }
531 
532  parse_nal_units(s, avctx, buf, buf_size);
533 
534  if (avctx->framerate.num)
535  avctx->time_base = av_inv_q(av_mul_q(avctx->framerate, (AVRational){avctx->ticks_per_frame, 1}));
536  if (h->sei_cpb_removal_delay >= 0) {
537  s->dts_sync_point = h->sei_buffering_period_present;
538  s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
539  s->pts_dts_delta = h->sei_dpb_output_delay;
540  } else {
541  s->dts_sync_point = INT_MIN;
542  s->dts_ref_dts_delta = INT_MIN;
543  s->pts_dts_delta = INT_MIN;
544  }
545 
546  if (s->flags & PARSER_FLAG_ONCE) {
547  s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
548  }
549 
550  *poutbuf = buf;
551  *poutbuf_size = buf_size;
552  return next;
553 }
554 
555 static int h264_split(AVCodecContext *avctx,
556  const uint8_t *buf, int buf_size)
557 {
558  uint32_t state = -1;
559  int has_sps = 0;
560  int has_pps = 0;
561  const uint8_t *ptr = buf, *end = buf + buf_size;
562  int nalu_type;
563 
564  while (ptr < end) {
565  ptr = avpriv_find_start_code(ptr, end, &state);
566  if ((state & 0xFFFFFF00) != 0x100)
567  break;
568  nalu_type = state & 0x1F;
569  if (nalu_type == NAL_SPS) {
570  has_sps = 1;
571  } else if (nalu_type == NAL_PPS)
572  has_pps = 1;
573  /* else if (nalu_type == 0x01 ||
574  * nalu_type == 0x02 ||
575  * nalu_type == 0x05) {
576  * }
577  */
578  else if ((nalu_type != NAL_SEI || has_pps) &&
579  nalu_type != NAL_AUD && nalu_type != NAL_SPS_EXT &&
580  nalu_type != 0x0f) {
581  if (has_sps) {
582  while (ptr - 4 > buf && ptr[-5] == 0)
583  ptr--;
584  return ptr - 4 - buf;
585  }
586  }
587  }
588 
589  return 0;
590 }
591 
592 static void h264_close(AVCodecParserContext *s)
593 {
594  H264ParseContext *p = s->priv_data;
595  H264Context *h = &p->h;
596  ParseContext *pc = &p->pc;
597 
598  av_freep(&pc->buffer);
599  ff_h264_free_context(h);
600 }
601 
602 static av_cold int init(AVCodecParserContext *s)
603 {
604  H264ParseContext *p = s->priv_data;
605  H264Context *h = &p->h;
606  h->thread_context[0] = h;
607  h->slice_context_count = 1;
608  ff_h264dsp_init(&h->h264dsp, 8, 1);
609  return 0;
610 }
611 
612 AVCodecParser ff_h264_parser = {
613  .codec_ids = { AV_CODEC_ID_H264 },
614  .priv_data_size = sizeof(H264ParseContext),
615  .parser_init = init,
616  .parser_parse = h264_parse,
617  .parser_close = h264_close,
618  .split = h264_split,
619 };
Generated on Sun Mar 8 2015 02:34:52 for FFmpeg by   doxygen 1.8.2