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mpeg4video_parser.c
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1 /*
2  * MPEG4 Video frame extraction
3  * Copyright (c) 2003 Fabrice Bellard
4  * Copyright (c) 2003 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 #define UNCHECKED_BITSTREAM_READER 1
24 
25 #include "internal.h"
26 #include "parser.h"
27 #include "mpegvideo.h"
28 #include "mpeg4video.h"
29 #include "mpeg4video_parser.h"
30 
35 };
36 
37 int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
38 {
39  int vop_found, i;
40  uint32_t state;
41 
42  vop_found = pc->frame_start_found;
43  state = pc->state;
44 
45  i = 0;
46  if (!vop_found) {
47  for (i = 0; i < buf_size; i++) {
48  state = (state << 8) | buf[i];
49  if (state == 0x1B6) {
50  i++;
51  vop_found = 1;
52  break;
53  }
54  }
55  }
56 
57  if (vop_found) {
58  /* EOF considered as end of frame */
59  if (buf_size == 0)
60  return 0;
61  for (; i < buf_size; i++) {
62  state = (state << 8) | buf[i];
63  if ((state & 0xFFFFFF00) == 0x100) {
64  pc->frame_start_found = 0;
65  pc->state = -1;
66  return i - 3;
67  }
68  }
69  }
70  pc->frame_start_found = vop_found;
71  pc->state = state;
72  return END_NOT_FOUND;
73 }
74 
75 /* XXX: make it use less memory */
77  const uint8_t *buf, int buf_size)
78 {
79  struct Mp4vParseContext *pc = s1->priv_data;
81  MpegEncContext *s = &dec_ctx->m;
82  GetBitContext gb1, *gb = &gb1;
83  int ret;
84 
85  s->avctx = avctx;
87 
88  if (avctx->extradata_size && pc->first_picture) {
89  init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8);
90  ret = ff_mpeg4_decode_picture_header(dec_ctx, gb);
91  }
92 
93  init_get_bits(gb, buf, 8 * buf_size);
94  ret = ff_mpeg4_decode_picture_header(dec_ctx, gb);
95  if (s->width && (!avctx->width || !avctx->height ||
96  !avctx->coded_width || !avctx->coded_height)) {
97  ret = ff_set_dimensions(avctx, s->width, s->height);
98  if (ret < 0)
99  return ret;
100  }
101  if((s1->flags & PARSER_FLAG_USE_CODEC_TS) && s->avctx->time_base.den>0 && ret>=0){
102  av_assert1(s1->pts == AV_NOPTS_VALUE);
103  av_assert1(s1->dts == AV_NOPTS_VALUE);
104 
105  s1->pts = av_rescale_q(s->time, (AVRational){1, s->avctx->time_base.den}, (AVRational){1, 1200000});
106  }
107 
108  s1->pict_type = s->pict_type;
109  pc->first_picture = 0;
110  return ret;
111 }
112 
114 {
115  struct Mp4vParseContext *pc = s->priv_data;
116 
118 
119  pc->first_picture = 1;
120  pc->dec_ctx.m.quant_precision = 5;
121  pc->dec_ctx.m.slice_context_count = 1;
123  return 0;
124 }
125 
127  AVCodecContext *avctx,
128  const uint8_t **poutbuf, int *poutbuf_size,
129  const uint8_t *buf, int buf_size)
130 {
131  ParseContext *pc = s->priv_data;
132  int next;
133 
135  next = buf_size;
136  } else {
137  next = ff_mpeg4_find_frame_end(pc, buf, buf_size);
138 
139  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
140  *poutbuf = NULL;
141  *poutbuf_size = 0;
142  return buf_size;
143  }
144  }
145  mpeg4_decode_header(s, avctx, buf, buf_size);
146 
147  *poutbuf = buf;
148  *poutbuf_size = buf_size;
149  return next;
150 }
151 
154  .priv_data_size = sizeof(struct Mp4vParseContext),
155  .parser_init = mpeg4video_parse_init,
156  .parser_parse = mpeg4video_parse,
157  .parser_close = ff_parse_close,
158  .split = ff_mpeg4video_split,
159 };