291e2c56aab48c1bc914c9422bffef97e0e57821
[libav.git] / libavformat / gsmdec.c
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"
25
26 #define GSM_BLOCK_SIZE 33
27 #define GSM_BLOCK_SAMPLES 160
28 #define GSM_SAMPLE_RATE 8000
29
30 typedef struct {
31 AVClass *class;
32 int sample_rate;
33 } GSMDemuxerContext;
34
35 static int gsm_read_packet(AVFormatContext *s, AVPacket *pkt)
36 {
37 int ret, size;
38
39 size = GSM_BLOCK_SIZE * 32;
40
41 if (av_new_packet(pkt, size) < 0)
42 return AVERROR(ENOMEM);
43
44 pkt->pos = avio_tell(s->pb);
45 pkt->stream_index = 0;
46
47 ret = av_get_packet(s->pb, pkt, size);
48 if (ret < GSM_BLOCK_SIZE) {
49 av_free_packet(pkt);
50 return ret < 0 ? ret : AVERROR(EIO);
51 }
52 pkt->size = ret;
53 pkt->duration = ret / GSM_BLOCK_SIZE;
54 pkt->pts = pkt->pos / GSM_BLOCK_SIZE;
55
56 return 0;
57 }
58
59 static int gsm_read_header(AVFormatContext *s, AVFormatParameters *ap)
60 {
61 GSMDemuxerContext *c = s->priv_data;
62 AVStream *st = avformat_new_stream(s, NULL);
63 if (!st)
64 return AVERROR(ENOMEM);
65
66 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
67 st->codec->codec_id = s->iformat->value;
68 st->codec->channels = 1;
69 st->codec->sample_rate = c->sample_rate;
70 st->codec->block_align = GSM_BLOCK_SIZE;
71 st->codec->bit_rate = GSM_BLOCK_SIZE * 8 * c->sample_rate / GSM_BLOCK_SAMPLES;
72
73 av_set_pts_info(st, 64, GSM_BLOCK_SAMPLES, GSM_SAMPLE_RATE);
74
75 return 0;
76 }
77
78 static int gsm_read_seek2(AVFormatContext *s, int stream_index, int64_t min_ts,
79 int64_t ts, int64_t max_ts, int flags)
80 {
81 GSMDemuxerContext *c = s->priv_data;
82
83 /* convert timestamps to file positions */
84 if (!(flags & AVSEEK_FLAG_BYTE)) {
85 if (stream_index < 0) {
86 AVRational bitrate_q = { GSM_BLOCK_SAMPLES, c->sample_rate * GSM_BLOCK_SIZE };
87 ts = av_rescale_q(ts, AV_TIME_BASE_Q, bitrate_q);
88 min_ts = av_rescale_q(min_ts, AV_TIME_BASE_Q, bitrate_q);
89 max_ts = av_rescale_q(max_ts, AV_TIME_BASE_Q, bitrate_q);
90 } else {
91 ts *= GSM_BLOCK_SIZE;
92 min_ts *= GSM_BLOCK_SIZE;
93 max_ts *= GSM_BLOCK_SIZE;
94 }
95 }
96 /* round to nearest block boundary */
97 ts = (ts + GSM_BLOCK_SIZE / 2) / GSM_BLOCK_SIZE * GSM_BLOCK_SIZE;
98 ts = FFMAX(0, ts);
99
100 /* handle min/max */
101 while (ts < min_ts)
102 ts += GSM_BLOCK_SIZE;
103 while (ts > max_ts)
104 ts -= GSM_BLOCK_SIZE;
105 if (ts < min_ts || ts > max_ts)
106 return -1;
107
108 return avio_seek(s->pb, ts, SEEK_SET);
109 }
110
111 static const AVOption options[] = {
112 { "sample_rate", "", offsetof(GSMDemuxerContext, sample_rate),
113 AV_OPT_TYPE_INT, {.dbl = GSM_SAMPLE_RATE}, 1, INT_MAX / GSM_BLOCK_SIZE,
114 AV_OPT_FLAG_DECODING_PARAM },
115 { NULL },
116 };
117
118 static const AVClass class = {
119 .class_name = "gsm demuxer",
120 .item_name = av_default_item_name,
121 .option = options,
122 .version = LIBAVUTIL_VERSION_INT,
123 };
124
125 AVInputFormat ff_gsm_demuxer = {
126 .name = "gsm",
127 .long_name = NULL_IF_CONFIG_SMALL("raw GSM"),
128 .priv_data_size = sizeof(GSMDemuxerContext),
129 .read_header = gsm_read_header,
130 .read_packet = gsm_read_packet,
131 .read_seek2 = gsm_read_seek2,
132 .extensions = "gsm",
133 .value = CODEC_ID_GSM,
134 .priv_class = &class,
135 };