oggparseskeleton.c
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1 /*
2  * Copyright (C) 2010 David Conrad
3  *
4  * This file is part of Libav.
5  *
6  * Libav is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * Libav is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with Libav; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "libavcodec/bytestream.h"
22 #include "avformat.h"
23 #include "internal.h"
24 #include "oggdec.h"
25 
26 static int skeleton_header(AVFormatContext *s, int idx)
27 {
28  struct ogg *ogg = s->priv_data;
29  struct ogg_stream *os = ogg->streams + idx;
30  AVStream *st = s->streams[idx];
31  uint8_t *buf = os->buf + os->pstart;
32  int version_major, version_minor;
33  int64_t start_num, start_den, start_granule;
34  int target_idx, start_time;
35 
36  strcpy(st->codec->codec_name, "skeleton");
38 
39  if (os->psize < 8)
40  return -1;
41 
42  if (!strncmp(buf, "fishead", 8)) {
43  if (os->psize < 64)
44  return -1;
45 
46  version_major = AV_RL16(buf+8);
47  version_minor = AV_RL16(buf+10);
48 
49  if (version_major != 3) {
50  av_log(s, AV_LOG_WARNING, "Unknown skeleton version %d.%d\n",
51  version_major, version_minor);
52  return -1;
53  }
54 
55  // This is the overall start time. We use it for the start time of
56  // of the skeleton stream since if left unset lavf assumes 0,
57  // which we don't want since skeleton is timeless
58  // FIXME: the real meaning of this field is "start playback at
59  // this time which can be in the middle of a packet
60  start_num = AV_RL64(buf+12);
61  start_den = AV_RL64(buf+20);
62 
63  if (start_den) {
64  int base_den;
65  av_reduce(&start_time, &base_den, start_num, start_den, INT_MAX);
66  avpriv_set_pts_info(st, 64, 1, base_den);
67  os->lastpts =
68  st->start_time = start_time;
69  }
70  } else if (!strncmp(buf, "fisbone", 8)) {
71  if (os->psize < 52)
72  return -1;
73 
74  target_idx = ogg_find_stream(ogg, AV_RL32(buf+12));
75  start_granule = AV_RL64(buf+36);
76  if (target_idx >= 0 && start_granule != -1) {
77  ogg->streams[target_idx].lastpts =
78  s->streams[target_idx]->start_time = ogg_gptopts(s, target_idx, start_granule, NULL);
79  }
80  }
81 
82  return 1;
83 }
84 
85 const struct ogg_codec ff_skeleton_codec = {
86  .magic = "fishead",
87  .magicsize = 8,
88  .header = skeleton_header,
89 };