Libav
vc1_parser.c
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1 /*
2  * VC-1 and WMV3 parser
3  * Copyright (c) 2006-2007 Konstantin Shishkov
4  * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer
5  *
6  * This file is part of Libav.
7  *
8  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
28 #include "libavutil/attributes.h"
29 #include "parser.h"
30 #include "vc1.h"
31 #include "get_bits.h"
32 
33 typedef struct {
37 
39  const uint8_t *buf, int buf_size)
40 {
41  VC1ParseContext *vpc = s->priv_data;
42  GetBitContext gb;
43  const uint8_t *start, *end, *next;
45 
46  vpc->v.s.avctx = avctx;
47  vpc->v.parse_only = 1;
48  next = buf;
49  s->repeat_pict = 0;
50 
51  for(start = buf, end = buf + buf_size; next < end; start = next){
52  int buf2_size, size;
53 
54  next = find_next_marker(start + 4, end);
55  size = next - start - 4;
56  buf2_size = vc1_unescape_buffer(start + 4, size, buf2);
57  init_get_bits(&gb, buf2, buf2_size * 8);
58  if(size <= 0) continue;
59  switch(AV_RB32(start)){
60  case VC1_CODE_SEQHDR:
61  ff_vc1_decode_sequence_header(avctx, &vpc->v, &gb);
62  break;
64  ff_vc1_decode_entry_point(avctx, &vpc->v, &gb);
65  break;
66  case VC1_CODE_FRAME:
67  if(vpc->v.profile < PROFILE_ADVANCED)
68  ff_vc1_parse_frame_header (&vpc->v, &gb);
69  else
70  ff_vc1_parse_frame_header_adv(&vpc->v, &gb);
71 
72  /* keep AV_PICTURE_TYPE_BI internal to VC1 */
73  if (vpc->v.s.pict_type == AV_PICTURE_TYPE_BI)
75  else
76  s->pict_type = vpc->v.s.pict_type;
77 
78  if (avctx->ticks_per_frame > 1){
79  // process pulldown flags
80  s->repeat_pict = 1;
81  // Pulldown flags are only valid when 'broadcast' has been set.
82  // So ticks_per_frame will be 2
83  if (vpc->v.rff){
84  // repeat field
85  s->repeat_pict = 2;
86  }else if (vpc->v.rptfrm){
87  // repeat frames
88  s->repeat_pict = vpc->v.rptfrm * 2 + 1;
89  }
90  }
91 
92  if (vpc->v.broadcast && vpc->v.interlace && !vpc->v.psf)
93  s->field_order = vpc->v.tff ? AV_FIELD_TT : AV_FIELD_BB;
94  else
96 
97  break;
98  }
99  }
100 
101  av_free(buf2);
102 }
103 
108 static int vc1_find_frame_end(ParseContext *pc, const uint8_t *buf,
109  int buf_size) {
110  int pic_found, i;
111  uint32_t state;
112 
113  pic_found= pc->frame_start_found;
114  state= pc->state;
115 
116  i=0;
117  if(!pic_found){
118  for(i=0; i<buf_size; i++){
119  state= (state<<8) | buf[i];
120  if(state == VC1_CODE_FRAME || state == VC1_CODE_FIELD){
121  i++;
122  pic_found=1;
123  break;
124  }
125  }
126  }
127 
128  if(pic_found){
129  /* EOF considered as end of frame */
130  if (buf_size == 0)
131  return 0;
132  for(; i<buf_size; i++){
133  state= (state<<8) | buf[i];
134  if(IS_MARKER(state) && state != VC1_CODE_FIELD && state != VC1_CODE_SLICE){
135  pc->frame_start_found=0;
136  pc->state=-1;
137  return i-3;
138  }
139  }
140  }
141  pc->frame_start_found= pic_found;
142  pc->state= state;
143  return END_NOT_FOUND;
144 }
145 
147  AVCodecContext *avctx,
148  const uint8_t **poutbuf, int *poutbuf_size,
149  const uint8_t *buf, int buf_size)
150 {
151  VC1ParseContext *vpc = s->priv_data;
152  int next;
153 
155  next= buf_size;
156  }else{
157  next= vc1_find_frame_end(&vpc->pc, buf, buf_size);
158 
159  if (ff_combine_frame(&vpc->pc, next, &buf, &buf_size) < 0) {
160  *poutbuf = NULL;
161  *poutbuf_size = 0;
162  return buf_size;
163  }
164  }
165 
166  vc1_extract_headers(s, avctx, buf, buf_size);
167 
168  *poutbuf = buf;
169  *poutbuf_size = buf_size;
170  return next;
171 }
172 
173 static int vc1_split(AVCodecContext *avctx,
174  const uint8_t *buf, int buf_size)
175 {
176  int i;
177  uint32_t state= -1;
178  int charged=0;
179 
180  for(i=0; i<buf_size; i++){
181  state= (state<<8) | buf[i];
182  if(IS_MARKER(state)){
183  if(state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT){
184  charged=1;
185  }else if(charged){
186  return i-3;
187  }
188  }
189  }
190  return 0;
191 }
192 
194 {
195  VC1ParseContext *vpc = s->priv_data;
196  vpc->v.s.slice_context_count = 1;
197  return ff_vc1_init_common(&vpc->v);
198 }
199 
201  .codec_ids = { AV_CODEC_ID_VC1 },
202  .priv_data_size = sizeof(VC1ParseContext),
203  .parser_init = vc1_parse_init,
204  .parser_parse = vc1_parse,
205  .parser_close = ff_parse_close,
206  .split = vc1_split,
207 };