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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 FFmpeg.
7  *
8  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * VC-1 and WMV3 parser
26  */
27 
28 #include "parser.h"
29 #include "vc1.h"
30 #include "get_bits.h"
31 
32 typedef struct {
36 
38  const uint8_t *buf, int buf_size)
39 {
40  VC1ParseContext *vpc = s->priv_data;
41  GetBitContext gb;
42  const uint8_t *start, *end, *next;
44 
45  vpc->v.s.avctx = avctx;
46  vpc->v.parse_only = 1;
47  next = buf;
48  s->repeat_pict = 0;
49 
50  for(start = buf, end = buf + buf_size; next < end; start = next){
51  int buf2_size, size;
52 
53  next = find_next_marker(start + 4, end);
54  size = next - start - 4;
55  buf2_size = vc1_unescape_buffer(start + 4, size, buf2);
56  init_get_bits(&gb, buf2, buf2_size * 8);
57  if(size <= 0) continue;
58  switch(AV_RB32(start)){
59  case VC1_CODE_SEQHDR:
60  ff_vc1_decode_sequence_header(avctx, &vpc->v, &gb);
61  break;
63  ff_vc1_decode_entry_point(avctx, &vpc->v, &gb);
64  break;
65  case VC1_CODE_FRAME:
66  if(vpc->v.profile < PROFILE_ADVANCED)
67  ff_vc1_parse_frame_header (&vpc->v, &gb);
68  else
69  ff_vc1_parse_frame_header_adv(&vpc->v, &gb);
70 
71  /* keep AV_PICTURE_TYPE_BI internal to VC1 */
72  if (vpc->v.s.pict_type == AV_PICTURE_TYPE_BI)
74  else
75  s->pict_type = vpc->v.s.pict_type;
76 
77  if (avctx->ticks_per_frame > 1){
78  // process pulldown flags
79  s->repeat_pict = 1;
80  // Pulldown flags are only valid when 'broadcast' has been set.
81  // So ticks_per_frame will be 2
82  if (vpc->v.rff){
83  // repeat field
84  s->repeat_pict = 2;
85  }else if (vpc->v.rptfrm){
86  // repeat frames
87  s->repeat_pict = vpc->v.rptfrm * 2 + 1;
88  }
89  }
90 
91  break;
92  }
93  }
94 
95  av_free(buf2);
96 }
97 
98 /**
99  * Find the end of the current frame in the bitstream.
100  * @return the position of the first byte of the next frame, or -1
101  */
102 static int vc1_find_frame_end(ParseContext *pc, const uint8_t *buf,
103  int buf_size) {
104  int pic_found, i;
105  uint32_t state;
106 
107  pic_found= pc->frame_start_found;
108  state= pc->state;
109 
110  i=0;
111  if(!pic_found){
112  for(i=0; i<buf_size; i++){
113  state= (state<<8) | buf[i];
114  if(state == VC1_CODE_FRAME || state == VC1_CODE_FIELD){
115  i++;
116  pic_found=1;
117  break;
118  }
119  }
120  }
121 
122  if(pic_found){
123  /* EOF considered as end of frame */
124  if (buf_size == 0)
125  return 0;
126  for(; i<buf_size; i++){
127  state= (state<<8) | buf[i];
128  if(IS_MARKER(state) && state != VC1_CODE_FIELD && state != VC1_CODE_SLICE){
129  pc->frame_start_found=0;
130  pc->state=-1;
131  return i-3;
132  }
133  }
134  }
135  pc->frame_start_found= pic_found;
136  pc->state= state;
137  return END_NOT_FOUND;
138 }
139 
141  AVCodecContext *avctx,
142  const uint8_t **poutbuf, int *poutbuf_size,
143  const uint8_t *buf, int buf_size)
144 {
145  VC1ParseContext *vpc = s->priv_data;
146  int next;
147 
149  next= buf_size;
150  }else{
151  next= vc1_find_frame_end(&vpc->pc, buf, buf_size);
152 
153  if (ff_combine_frame(&vpc->pc, next, &buf, &buf_size) < 0) {
154  *poutbuf = NULL;
155  *poutbuf_size = 0;
156  return buf_size;
157  }
158  }
159 
160  vc1_extract_headers(s, avctx, buf, buf_size);
161 
162  *poutbuf = buf;
163  *poutbuf_size = buf_size;
164  return next;
165 }
166 
167 static int vc1_split(AVCodecContext *avctx,
168  const uint8_t *buf, int buf_size)
169 {
170  int i;
171  uint32_t state= -1;
172  int charged=0;
173 
174  for(i=0; i<buf_size; i++){
175  state= (state<<8) | buf[i];
176  if(IS_MARKER(state)){
177  if(state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT){
178  charged=1;
179  }else if(charged){
180  return i-3;
181  }
182  }
183  }
184  return 0;
185 }
186 
188 {
189  VC1ParseContext *vpc = s->priv_data;
190  vpc->v.s.slice_context_count = 1;
191  return ff_vc1_init_common(&vpc->v);
192 }
193 
195  .codec_ids = { AV_CODEC_ID_VC1 },
196  .priv_data_size = sizeof(VC1ParseContext),
197  .parser_init = vc1_parse_init,
198  .parser_parse = vc1_parse,
199  .parser_close = ff_parse_close,
200  .split = vc1_split,
201 };