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libavformat/oggparseskeleton.c

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00001 /*
00002  * Copyright (C) 2010 David Conrad
00003  *
00004  * This file is part of FFmpeg.
00005  *
00006  * FFmpeg is free software; you can redistribute it and/or
00007  * modify it under the terms of the GNU Lesser General Public
00008  * License as published by the Free Software Foundation; either
00009  * version 2.1 of the License, or (at your option) any later version.
00010  *
00011  * FFmpeg is distributed in the hope that it will be useful,
00012  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014  * Lesser General Public License for more details.
00015  *
00016  * You should have received a copy of the GNU Lesser General Public
00017  * License along with FFmpeg; if not, write to the Free Software
00018  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00019  */
00020 
00021 #include "libavcodec/bytestream.h"
00022 #include "avformat.h"
00023 #include "oggdec.h"
00024 
00025 static int skeleton_header(AVFormatContext *s, int idx)
00026 {
00027     struct ogg *ogg = s->priv_data;
00028     struct ogg_stream *os = ogg->streams + idx;
00029     AVStream *st = s->streams[idx];
00030     uint8_t *buf = os->buf + os->pstart;
00031     int version_major, version_minor;
00032     int64_t start_num, start_den, start_granule;
00033     int target_idx, start_time;
00034 
00035     strcpy(st->codec->codec_name, "skeleton");
00036     st->codec->codec_type = AVMEDIA_TYPE_DATA;
00037 
00038     if (os->psize < 8)
00039         return -1;
00040 
00041     if (!strncmp(buf, "fishead", 8)) {
00042         if (os->psize < 64)
00043             return -1;
00044 
00045         version_major = AV_RL16(buf+8);
00046         version_minor = AV_RL16(buf+10);
00047 
00048         if (version_major != 3) {
00049             av_log(s, AV_LOG_WARNING, "Unknown skeleton version %d.%d\n",
00050                    version_major, version_minor);
00051             return -1;
00052         }
00053 
00054         // This is the overall start time. We use it for the start time of
00055         // of the skeleton stream since if left unset lavf assumes 0,
00056         // which we don't want since skeleton is timeless
00057         // FIXME: the real meaning of this field is "start playback at
00058         // this time which can be in the middle of a packet
00059         start_num = AV_RL64(buf+12);
00060         start_den = AV_RL64(buf+20);
00061 
00062         if (start_den) {
00063             av_reduce(&start_time, &st->time_base.den, start_num, start_den, INT_MAX);
00064             st->time_base.num = 1;
00065             os->lastpts =
00066             st->start_time = start_time;
00067         }
00068     } else if (!strncmp(buf, "fisbone", 8)) {
00069         if (os->psize < 52)
00070             return -1;
00071 
00072         target_idx = ogg_find_stream(ogg, AV_RL32(buf+12));
00073         start_granule = AV_RL64(buf+36);
00074         if (target_idx >= 0 && start_granule != -1) {
00075             ogg->streams[target_idx].lastpts =
00076             s->streams[target_idx]->start_time = ogg_gptopts(s, target_idx, start_granule, NULL);
00077         }
00078     }
00079 
00080     return 1;
00081 }
00082 
00083 const struct ogg_codec ff_skeleton_codec = {
00084     .magic = "fishead",
00085     .magicsize = 8,
00086     .header = skeleton_header,
00087 };

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