gsm demuxer: return packets with only 1 gsm block at a time.
[libav.git] / libavformat / gsmdec.c
CommitLineData
87c57d80
JR
1/*
2 * RAW GSM demuxer
3 * Copyright (c) 2011 Justin Ruggles
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; 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 "libavutil/opt.h"
24#include "avformat.h"
c3f9ebf7 25#include "internal.h"
87c57d80
JR
26
27#define GSM_BLOCK_SIZE 33
28#define GSM_BLOCK_SAMPLES 160
29#define GSM_SAMPLE_RATE 8000
30
31typedef struct {
32 AVClass *class;
33 int sample_rate;
34} GSMDemuxerContext;
35
36static int gsm_read_packet(AVFormatContext *s, AVPacket *pkt)
37{
38 int ret, size;
39
467879eb 40 size = GSM_BLOCK_SIZE;
87c57d80 41
87c57d80
JR
42 pkt->pos = avio_tell(s->pb);
43 pkt->stream_index = 0;
44
45 ret = av_get_packet(s->pb, pkt, size);
46 if (ret < GSM_BLOCK_SIZE) {
47 av_free_packet(pkt);
48 return ret < 0 ? ret : AVERROR(EIO);
49 }
50 pkt->size = ret;
467879eb 51 pkt->duration = 1;
87c57d80
JR
52 pkt->pts = pkt->pos / GSM_BLOCK_SIZE;
53
54 return 0;
55}
56
57static int gsm_read_header(AVFormatContext *s, AVFormatParameters *ap)
58{
59 GSMDemuxerContext *c = s->priv_data;
60 AVStream *st = avformat_new_stream(s, NULL);
61 if (!st)
62 return AVERROR(ENOMEM);
63
64 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
65 st->codec->codec_id = s->iformat->value;
66 st->codec->channels = 1;
67 st->codec->sample_rate = c->sample_rate;
87c57d80
JR
68 st->codec->bit_rate = GSM_BLOCK_SIZE * 8 * c->sample_rate / GSM_BLOCK_SAMPLES;
69
c3f9ebf7 70 avpriv_set_pts_info(st, 64, GSM_BLOCK_SAMPLES, GSM_SAMPLE_RATE);
87c57d80
JR
71
72 return 0;
73}
74
75static int gsm_read_seek2(AVFormatContext *s, int stream_index, int64_t min_ts,
76 int64_t ts, int64_t max_ts, int flags)
77{
78 GSMDemuxerContext *c = s->priv_data;
79
80 /* convert timestamps to file positions */
81 if (!(flags & AVSEEK_FLAG_BYTE)) {
82 if (stream_index < 0) {
83 AVRational bitrate_q = { GSM_BLOCK_SAMPLES, c->sample_rate * GSM_BLOCK_SIZE };
84 ts = av_rescale_q(ts, AV_TIME_BASE_Q, bitrate_q);
85 min_ts = av_rescale_q(min_ts, AV_TIME_BASE_Q, bitrate_q);
86 max_ts = av_rescale_q(max_ts, AV_TIME_BASE_Q, bitrate_q);
87 } else {
88 ts *= GSM_BLOCK_SIZE;
89 min_ts *= GSM_BLOCK_SIZE;
90 max_ts *= GSM_BLOCK_SIZE;
91 }
92 }
93 /* round to nearest block boundary */
94 ts = (ts + GSM_BLOCK_SIZE / 2) / GSM_BLOCK_SIZE * GSM_BLOCK_SIZE;
95 ts = FFMAX(0, ts);
96
97 /* handle min/max */
98 while (ts < min_ts)
99 ts += GSM_BLOCK_SIZE;
100 while (ts > max_ts)
101 ts -= GSM_BLOCK_SIZE;
102 if (ts < min_ts || ts > max_ts)
103 return -1;
104
105 return avio_seek(s->pb, ts, SEEK_SET);
106}
107
108static const AVOption options[] = {
109 { "sample_rate", "", offsetof(GSMDemuxerContext, sample_rate),
110 AV_OPT_TYPE_INT, {.dbl = GSM_SAMPLE_RATE}, 1, INT_MAX / GSM_BLOCK_SIZE,
111 AV_OPT_FLAG_DECODING_PARAM },
112 { NULL },
113};
114
115static const AVClass class = {
116 .class_name = "gsm demuxer",
117 .item_name = av_default_item_name,
118 .option = options,
119 .version = LIBAVUTIL_VERSION_INT,
120};
121
122AVInputFormat ff_gsm_demuxer = {
123 .name = "gsm",
124 .long_name = NULL_IF_CONFIG_SMALL("raw GSM"),
125 .priv_data_size = sizeof(GSMDemuxerContext),
126 .read_header = gsm_read_header,
127 .read_packet = gsm_read_packet,
128 .read_seek2 = gsm_read_seek2,
129 .extensions = "gsm",
130 .value = CODEC_ID_GSM,
131 .priv_class = &class,
132};