FFmpeg/libavformat/oggparseskeleton.c
David Conrad 32ad869284 oggdec: Parse skeleton to determine the start time of each stream
Originally committed as revision 22457 to svn://svn.ffmpeg.org/ffmpeg/trunk
2010-03-11 07:17:40 +00:00

86 lines
2.8 KiB
C

/*
* Copyright (C) 2010 David Conrad
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavcodec/bytestream.h"
#include "avformat.h"
#include "oggdec.h"
static int skeleton_header(AVFormatContext *s, int idx)
{
struct ogg *ogg = s->priv_data;
struct ogg_stream *os = ogg->streams + idx;
AVStream *st = s->streams[idx];
uint8_t *buf = os->buf + os->pstart;
int version_major, version_minor;
int64_t start_num, start_den, start_granule;
int target_idx, start_time;
strcpy(st->codec->codec_name, "skeleton");
st->codec->codec_type = CODEC_TYPE_DATA;
if (os->psize < 8)
return -1;
if (!strncmp(buf, "fishead", 8)) {
if (os->psize < 64)
return -1;
version_major = AV_RL16(buf+8);
version_minor = AV_RL16(buf+10);
if (version_major != 3) {
av_log(s, AV_LOG_WARNING, "Unknown skeleton version %d.%d\n",
version_major, version_minor);
return -1;
}
// This is the overall start time. We use it for the start time of
// of the skeleton stream since if left unset lavf assumes 0,
// which we don't want since skeleton is timeless
// FIXME: the real meaning of this field is "start playback at
// this time which can be in the middle of a packet
start_num = AV_RL64(buf+12);
start_den = AV_RL64(buf+20);
if (start_den) {
av_reduce(&start_time, &st->time_base.den, start_num, start_den, INT_MAX);
st->time_base.num = 1;
st->start_time = start_time;
}
} else if (!strncmp(buf, "fisbone", 8)) {
if (os->psize < 52)
return -1;
target_idx = ogg_find_stream(ogg, AV_RL32(buf+12));
start_granule = AV_RL64(buf+36);
if (target_idx >= 0 && start_granule != -1) {
s->streams[target_idx]->start_time = ogg_gptopts(s, target_idx, start_granule, NULL);
}
}
return 1;
}
const struct ogg_codec ff_skeleton_codec = {
.magic = "fishead",
.magicsize = 8,
.header = skeleton_header,
};