3 * Copyright (c) 2003 Fabrice Bellard
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 #include "libavutil/mathematics.h"
26 int ff_pcm_read_seek(AVFormatContext *s,
27 int stream_index, int64_t timestamp, int flags)
30 int block_align, byte_rate;
35 block_align = st->codec->block_align ? st->codec->block_align :
36 (av_get_bits_per_sample(st->codec->codec_id) * st->codec->channels) >> 3;
37 byte_rate = st->codec->bit_rate ? st->codec->bit_rate >> 3 :
38 block_align * st->codec->sample_rate;
40 if (block_align <= 0 || byte_rate <= 0)
42 if (timestamp < 0) timestamp = 0;
44 /* compute the position by aligning it to block_align */
45 pos = av_rescale_rnd(timestamp * byte_rate,
47 st->time_base.den * (int64_t)block_align,
48 (flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP);
51 /* recompute exact position */
52 st->cur_dts = av_rescale(pos, st->time_base.den, byte_rate * (int64_t)st->time_base.num);
53 if ((ret = avio_seek(s->pb, pos + s->data_offset, SEEK_SET)) < 0)