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2ba45a60 DM |
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 | ||
28 | int 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 | ||
44 | int 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 | } |