mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-23 12:43:46 +02:00
56 lines
2.0 KiB
C
56 lines
2.0 KiB
C
/*
|
|
* PCM common functions
|
|
* Copyright (c) 2003 Fabrice Bellard
|
|
*
|
|
* This file is part of Libav.
|
|
*
|
|
* Libav 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.
|
|
*
|
|
* Libav 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 Libav; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#include "avformat.h"
|
|
#include "pcm.h"
|
|
|
|
int pcm_read_seek(AVFormatContext *s,
|
|
int stream_index, int64_t timestamp, int flags)
|
|
{
|
|
AVStream *st;
|
|
int block_align, byte_rate;
|
|
int64_t pos, ret;
|
|
|
|
st = s->streams[0];
|
|
|
|
block_align = st->codec->block_align ? st->codec->block_align :
|
|
(av_get_bits_per_sample(st->codec->codec_id) * st->codec->channels) >> 3;
|
|
byte_rate = st->codec->bit_rate ? st->codec->bit_rate >> 3 :
|
|
block_align * st->codec->sample_rate;
|
|
|
|
if (block_align <= 0 || byte_rate <= 0)
|
|
return -1;
|
|
if (timestamp < 0) timestamp = 0;
|
|
|
|
/* compute the position by aligning it to block_align */
|
|
pos = av_rescale_rnd(timestamp * byte_rate,
|
|
st->time_base.num,
|
|
st->time_base.den * (int64_t)block_align,
|
|
(flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP);
|
|
pos *= block_align;
|
|
|
|
/* recompute exact position */
|
|
st->cur_dts = av_rescale(pos, st->time_base.den, byte_rate * (int64_t)st->time_base.num);
|
|
if ((ret = avio_seek(s->pb, pos + s->data_offset, SEEK_SET)) < 0)
|
|
return ret;
|
|
return 0;
|
|
}
|