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 Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
28 #include "parser.h"
29 #include "h264data.h"
30 #include "golomb.h"
31 
32 #include <assert.h>
33 
34 
35 static int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)
36 {
37  int i;
38  uint32_t state;
39  ParseContext *pc = &(h->s.parse_context);
40 //printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);
41 // mb_addr= pc->mb_addr - 1;
42  state= pc->state;
43  if(state>13)
44  state= 7;
45 
46  for(i=0; i<buf_size; i++){
47  if(state==7){
48 #if HAVE_FAST_UNALIGNED
49  /* we check i<buf_size instead of i+3/7 because its simpler
50  * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
51  */
52 # if HAVE_FAST_64BIT
53  while(i<buf_size && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
54  i+=8;
55 # else
56  while(i<buf_size && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
57  i+=4;
58 # endif
59 #endif
60  for(; i<buf_size; i++){
61  if(!buf[i]){
62  state=2;
63  break;
64  }
65  }
66  }else if(state<=2){
67  if(buf[i]==1) state^= 5; //2->7, 1->4, 0->5
68  else if(buf[i]) state = 7;
69  else state>>=1; //2->1, 1->0, 0->0
70  }else if(state<=5){
71  int v= buf[i] & 0x1F;
72  if(v==6 || v==7 || v==8 || v==9){
73  if(pc->frame_start_found){
74  i++;
75  goto found;
76  }
77  }else if(v==1 || v==2 || v==5){
78  if(pc->frame_start_found){
79  state+=8;
80  continue;
81  }else
82  pc->frame_start_found = 1;
83  }
84  state= 7;
85  }else{
86  if(buf[i] & 0x80)
87  goto found;
88  state= 7;
89  }
90  }
91  pc->state= state;
92  return END_NOT_FOUND;
93 
94 found:
95  pc->state=7;
96  pc->frame_start_found= 0;
97  return i-(state&5);
98 }
99 
109  AVCodecContext *avctx,
110  const uint8_t *buf, int buf_size)
111 {
112  H264Context *h = s->priv_data;
113  const uint8_t *buf_end = buf + buf_size;
114  unsigned int pps_id;
115  unsigned int slice_type;
116  int state = -1;
117  const uint8_t *ptr;
118 
119  /* set some sane default values */
121  s->key_frame = 0;
122 
123  h->s.avctx= avctx;
124  h->sei_recovery_frame_cnt = -1;
125  h->sei_dpb_output_delay = 0;
126  h->sei_cpb_removal_delay = -1;
128 
129  if (!buf_size)
130  return 0;
131 
132  for(;;) {
133  int src_length, dst_length, consumed;
134  buf = avpriv_mpv_find_start_code(buf, buf_end, &state);
135  if(buf >= buf_end)
136  break;
137  --buf;
138  src_length = buf_end - buf;
139  switch (state & 0x1f) {
140  case NAL_SLICE:
141  case NAL_IDR_SLICE:
142  // Do not walk the whole buffer just to decode slice header
143  if (src_length > 20)
144  src_length = 20;
145  break;
146  }
147  ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
148  if (ptr==NULL || dst_length < 0)
149  break;
150 
151  init_get_bits(&h->s.gb, ptr, 8*dst_length);
152  switch(h->nal_unit_type) {
153  case NAL_SPS:
155  break;
156  case NAL_PPS:
158  break;
159  case NAL_SEI:
161  break;
162  case NAL_IDR_SLICE:
163  s->key_frame = 1;
164  /* fall through */
165  case NAL_SLICE:
166  get_ue_golomb(&h->s.gb); // skip first_mb_in_slice
167  slice_type = get_ue_golomb_31(&h->s.gb);
168  s->pict_type = golomb_to_pict_type[slice_type % 5];
169  if (h->sei_recovery_frame_cnt >= 0) {
170  /* key frame, since recovery_frame_cnt is set */
171  s->key_frame = 1;
172  }
173  pps_id= get_ue_golomb(&h->s.gb);
174  if(pps_id>=MAX_PPS_COUNT) {
175  av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
176  return -1;
177  }
178  if(!h->pps_buffers[pps_id]) {
179  av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
180  return -1;
181  }
182  h->pps= *h->pps_buffers[pps_id];
183  if(!h->sps_buffers[h->pps.sps_id]) {
184  av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
185  return -1;
186  }
187  h->sps = *h->sps_buffers[h->pps.sps_id];
189 
190  avctx->profile = ff_h264_get_profile(&h->sps);
191  avctx->level = h->sps.level_idc;
192 
193  if(h->sps.frame_mbs_only_flag){
195  }else{
196  if(get_bits1(&h->s.gb)) { //field_pic_flag
197  h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
198  } else {
200  }
201  }
202 
204  switch (h->sei_pic_struct) {
207  s->repeat_pict = 0;
208  break;
212  s->repeat_pict = 1;
213  break;
216  s->repeat_pict = 2;
217  break;
219  s->repeat_pict = 3;
220  break;
222  s->repeat_pict = 5;
223  break;
224  default:
225  s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
226  break;
227  }
228  } else {
229  s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
230  }
231 
232  return 0; /* no need to evaluate the rest */
233  }
234  buf += consumed;
235  }
236  /* didn't find a picture! */
237  av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit\n");
238  return -1;
239 }
240 
242  AVCodecContext *avctx,
243  const uint8_t **poutbuf, int *poutbuf_size,
244  const uint8_t *buf, int buf_size)
245 {
246  H264Context *h = s->priv_data;
247  ParseContext *pc = &h->s.parse_context;
248  int next;
249 
250  if (!h->got_first) {
251  h->got_first = 1;
252  if (avctx->extradata_size) {
253  h->s.avctx = avctx;
254  // must be done like in the decoder.
255  // otherwise opening the parser, creating extradata,
256  // and then closing and opening again
257  // will cause has_b_frames to be always set.
258  // NB: estimate_timings_from_pts behaves exactly like this.
259  if (!avctx->has_b_frames)
260  h->s.low_delay = 1;
262  }
263  }
264 
266  next= buf_size;
267  }else{
268  next= ff_h264_find_frame_end(h, buf, buf_size);
269 
270  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
271  *poutbuf = NULL;
272  *poutbuf_size = 0;
273  return buf_size;
274  }
275 
276  if(next<0 && next != END_NOT_FOUND){
277  assert(pc->last_index + next >= 0 );
278  ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
279  }
280  }
281 
282  parse_nal_units(s, avctx, buf, buf_size);
283 
284  if (h->sei_cpb_removal_delay >= 0) {
288  } else {
289  s->dts_sync_point = INT_MIN;
290  s->dts_ref_dts_delta = INT_MIN;
291  s->pts_dts_delta = INT_MIN;
292  }
293 
294  if (s->flags & PARSER_FLAG_ONCE) {
296  }
297 
298  *poutbuf = buf;
299  *poutbuf_size = buf_size;
300  return next;
301 }
302 
303 static int h264_split(AVCodecContext *avctx,
304  const uint8_t *buf, int buf_size)
305 {
306  int i;
307  uint32_t state = -1;
308  int has_sps= 0;
309 
310  for(i=0; i<=buf_size; i++){
311  if((state&0xFFFFFF1F) == 0x107)
312  has_sps=1;
313 /* if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
314  }*/
315  if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
316  if(has_sps){
317  while(i>4 && buf[i-5]==0) i--;
318  return i-4;
319  }
320  }
321  if (i<buf_size)
322  state= (state<<8) | buf[i];
323  }
324  return 0;
325 }
326 
328 {
329  H264Context *h = s->priv_data;
330  ParseContext *pc = &h->s.parse_context;
331 
332  av_free(pc->buffer);
334 }
335 
337 {
338  H264Context *h = s->priv_data;
339  h->thread_context[0] = h;
340  h->s.slice_context_count = 1;
341  return 0;
342 }
343 
345  .codec_ids = { CODEC_ID_H264 },
346  .priv_data_size = sizeof(H264Context),
347  .parser_init = init,
348  .parser_parse = h264_parse,
349  .parser_close = close,
350  .split = h264_split,
351 };