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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 "parser.h"
31 #include "h264data.h"
32 #include "golomb.h"
33 
34 
35 static int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)
36 {
37  int i, j;
38  uint32_t state;
39  ParseContext *pc = &(h->s.parse_context);
40  int next_avc= h->is_avc ? 0 : buf_size;
41 
42 // mb_addr= pc->mb_addr - 1;
43  state= pc->state;
44  if(state>13)
45  state= 7;
46 
47  if(h->is_avc && !h->nal_length_size)
48  av_log(h->s.avctx, AV_LOG_ERROR, "AVC-parser: nal length size invalid\n");
49 
50  for(i=0; i<buf_size; i++){
51  if(i >= next_avc) {
52  int nalsize = 0;
53  i = next_avc;
54  for(j = 0; j < h->nal_length_size; j++)
55  nalsize = (nalsize << 8) | buf[i++];
56  if(nalsize <= 0 || nalsize > buf_size - i){
57  av_log(h->s.avctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);
58  return buf_size;
59  }
60  next_avc= i + nalsize;
61  state= 5;
62  }
63 
64  if(state==7){
65 #if HAVE_FAST_UNALIGNED
66  /* we check i<buf_size instead of i+3/7 because its simpler
67  * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
68  */
69 # if HAVE_FAST_64BIT
70  while(i<next_avc && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
71  i+=8;
72 # else
73  while(i<next_avc && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
74  i+=4;
75 # endif
76 #endif
77  for(; i<next_avc; i++){
78  if(!buf[i]){
79  state=2;
80  break;
81  }
82  }
83  }else if(state<=2){
84  if(buf[i]==1) state^= 5; //2->7, 1->4, 0->5
85  else if(buf[i]) state = 7;
86  else state>>=1; //2->1, 1->0, 0->0
87  }else if(state<=5){
88  int v= buf[i] & 0x1F;
89  if(v==6 || v==7 || v==8 || v==9){
90  if(pc->frame_start_found){
91  i++;
92  goto found;
93  }
94  }else if(v==1 || v==2 || v==5){
95  state+=8;
96  continue;
97  }
98  state= 7;
99  }else{
100  h->parse_history[h->parse_history_count++]= buf[i];
101  if(h->parse_history_count>3){
102  unsigned int mb, last_mb= h->parse_last_mb;
103  GetBitContext gb;
104 
106  h->parse_history_count=0;
107  mb= get_ue_golomb_long(&gb);
108  last_mb= h->parse_last_mb;
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) - 3*(state>7);
130 }
131 
132 /**
133  * Parse NAL units of found picture and decode some basic information.
134  *
135  * @param s parser context.
136  * @param avctx codec context.
137  * @param buf buffer with field/frame data.
138  * @param buf_size size of the buffer.
139  */
141  AVCodecContext *avctx,
142  const uint8_t *buf, int buf_size)
143 {
144  H264Context *h = s->priv_data;
145  const uint8_t *buf_end = buf + buf_size;
146  unsigned int pps_id;
147  unsigned int slice_type;
148  int state = -1;
149  const uint8_t *ptr;
150  int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);
151 
152  /* set some sane default values */
154  s->key_frame = 0;
155 
156  h->s.avctx= avctx;
157  h->sei_recovery_frame_cnt = -1;
158  h->sei_dpb_output_delay = 0;
159  h->sei_cpb_removal_delay = -1;
161 
162  if (!buf_size)
163  return 0;
164 
165  for(;;) {
166  int src_length, dst_length, consumed, nalsize = 0;
167  if (h->is_avc) {
168  int i;
169  if (h->nal_length_size >= buf_end - buf) break;
170  nalsize = 0;
171  for (i = 0; i < h->nal_length_size; i++)
172  nalsize = (nalsize << 8) | *buf++;
173  if (nalsize <= 0 || nalsize > buf_end - buf) {
174  av_log(h->s.avctx, AV_LOG_ERROR, "AVC: nal size %d\n", nalsize);
175  break;
176  }
177  src_length = nalsize;
178  } else {
179  buf = avpriv_mpv_find_start_code(buf, buf_end, &state);
180  if(buf >= buf_end)
181  break;
182  --buf;
183  src_length = buf_end - buf;
184  }
185  switch (state & 0x1f) {
186  case NAL_SLICE:
187  case NAL_IDR_SLICE:
188  // Do not walk the whole buffer just to decode slice header
189  if (src_length > 20)
190  src_length = 20;
191  break;
192  }
193  ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
194  if (ptr==NULL || dst_length < 0)
195  break;
196 
197  init_get_bits(&h->s.gb, ptr, 8*dst_length);
198  switch(h->nal_unit_type) {
199  case NAL_SPS:
201  break;
202  case NAL_PPS:
204  break;
205  case NAL_SEI:
207  break;
208  case NAL_IDR_SLICE:
209  s->key_frame = 1;
210  /* fall through */
211  case NAL_SLICE:
212  get_ue_golomb_long(&h->s.gb); // skip first_mb_in_slice
213  slice_type = get_ue_golomb_31(&h->s.gb);
214  s->pict_type = golomb_to_pict_type[slice_type % 5];
215  if (h->sei_recovery_frame_cnt >= 0) {
216  /* key frame, since recovery_frame_cnt is set */
217  s->key_frame = 1;
218  }
219  pps_id= get_ue_golomb(&h->s.gb);
220  if(pps_id>=MAX_PPS_COUNT) {
221  av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
222  return -1;
223  }
224  if(!h->pps_buffers[pps_id]) {
225  av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
226  return -1;
227  }
228  h->pps= *h->pps_buffers[pps_id];
229  if(!h->sps_buffers[h->pps.sps_id]) {
230  av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
231  return -1;
232  }
233  h->sps = *h->sps_buffers[h->pps.sps_id];
235 
236  avctx->profile = ff_h264_get_profile(&h->sps);
237  avctx->level = h->sps.level_idc;
238 
239  if(h->sps.frame_mbs_only_flag){
241  }else{
242  if(get_bits1(&h->s.gb)) { //field_pic_flag
243  h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
244  } else {
246  }
247  }
248 
250  switch (h->sei_pic_struct) {
253  s->repeat_pict = 0;
254  break;
258  s->repeat_pict = 1;
259  break;
262  s->repeat_pict = 2;
263  break;
265  s->repeat_pict = 3;
266  break;
268  s->repeat_pict = 5;
269  break;
270  default:
271  s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
272  break;
273  }
274  } else {
275  s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
276  }
277 
278  return 0; /* no need to evaluate the rest */
279  }
280  buf += h->is_avc ? nalsize : consumed;
281  }
282  if (q264)
283  return 0;
284  /* didn't find a picture! */
285  av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);
286  return -1;
287 }
288 
290  AVCodecContext *avctx,
291  const uint8_t **poutbuf, int *poutbuf_size,
292  const uint8_t *buf, int buf_size)
293 {
294  H264Context *h = s->priv_data;
295  ParseContext *pc = &h->s.parse_context;
296  int next;
297 
298  if (!h->got_first) {
299  h->got_first = 1;
300  if (avctx->extradata_size) {
301  h->s.avctx = avctx;
302  // must be done like in decoder, otherwise opening the parser,
303  // letting it create extradata and then closing and opening again
304  // will cause has_b_frames to be always set.
305  // Note that estimate_timings_from_pts does exactly this.
306  if (!avctx->has_b_frames)
307  h->s.low_delay = 1;
309  }
310  }
311 
313  next= buf_size;
314  }else{
315  next= ff_h264_find_frame_end(h, buf, buf_size);
316 
317  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
318  *poutbuf = NULL;
319  *poutbuf_size = 0;
320  return buf_size;
321  }
322 
323  if(next<0 && next != END_NOT_FOUND){
324  av_assert1(pc->last_index + next >= 0 );
325  ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
326  }
327  }
328 
329  parse_nal_units(s, avctx, buf, buf_size);
330 
331  if (h->sei_cpb_removal_delay >= 0) {
335  } else {
336  s->dts_sync_point = INT_MIN;
337  s->dts_ref_dts_delta = INT_MIN;
338  s->pts_dts_delta = INT_MIN;
339  }
340 
341  if (s->flags & PARSER_FLAG_ONCE) {
343  }
344 
345  *poutbuf = buf;
346  *poutbuf_size = buf_size;
347  return next;
348 }
349 
350 static int h264_split(AVCodecContext *avctx,
351  const uint8_t *buf, int buf_size)
352 {
353  int i;
354  uint32_t state = -1;
355  int has_sps= 0;
356 
357  for(i=0; i<=buf_size; i++){
358  if((state&0xFFFFFF1F) == 0x107)
359  has_sps=1;
360 /* if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
361  }*/
362  if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
363  if(has_sps){
364  while(i>4 && buf[i-5]==0) i--;
365  return i-4;
366  }
367  }
368  if (i<buf_size)
369  state= (state<<8) | buf[i];
370  }
371  return 0;
372 }
373 
375 {
376  H264Context *h = s->priv_data;
377  ParseContext *pc = &h->s.parse_context;
378 
379  av_free(pc->buffer);
381 }
382 
384 {
385  H264Context *h = s->priv_data;
386  h->thread_context[0] = h;
387  h->s.slice_context_count = 1;
388  return 0;
389 }
390 
393  .priv_data_size = sizeof(H264Context),
394  .parser_init = init,
395  .parser_parse = h264_parse,
396  .parser_close = close,
397  .split = h264_split,
398 };