1/*
2 * PCM common functions
3 * Copyright (c) 2003 Fabrice Bellard
4 *
5 * This file is part of FFmpeg.
6 *
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.
11 *
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.
16 *
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
20 */
21
22#include "libavutil/mathematics.h"
23#include "avformat.h"
24#include "pcm.h"
25
26#define RAW_SAMPLES     1024
27
28int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt)
29{
30    int ret, size;
31
32    size= RAW_SAMPLES*s->streams[0]->codec->block_align;
33    if (size <= 0)
34        return AVERROR(EINVAL);
35
36    ret= av_get_packet(s->pb, pkt, size);
37
38    pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
39    pkt->stream_index = 0;
40
41    return ret;
42}
43
44int ff_pcm_read_seek(AVFormatContext *s,
45                     int stream_index, int64_t timestamp, int flags)
46{
47    AVStream *st;
48    int block_align, byte_rate;
49    int64_t pos, ret;
50
51    st = s->streams[0];
52
53    block_align = st->codec->block_align ? st->codec->block_align :
54        (av_get_bits_per_sample(st->codec->codec_id) * st->codec->channels) >> 3;
55    byte_rate = st->codec->bit_rate ? st->codec->bit_rate >> 3 :
56        block_align * st->codec->sample_rate;
57
58    if (block_align <= 0 || byte_rate <= 0)
59        return -1;
60    if (timestamp < 0) timestamp = 0;
61
62    /* compute the position by aligning it to block_align */
63    pos = av_rescale_rnd(timestamp * byte_rate,
64                         st->time_base.num,
65                         st->time_base.den * (int64_t)block_align,
66                         (flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP);
67    pos *= block_align;
68
69    /* recompute exact position */
70    st->cur_dts = av_rescale(pos, st->time_base.den, byte_rate * (int64_t)st->time_base.num);
71    if ((ret = avio_seek(s->pb, pos + s->data_offset, SEEK_SET)) < 0)
72        return ret;
73    return 0;
74}
75