23608873c12b0ab7948cce0c87c3558e5254f3e5
[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 #include "internal.h"
26
27 #define GSM_BLOCK_SIZE 33
28 #define GSM_BLOCK_SAMPLES 160
29 #define GSM_SAMPLE_RATE 8000
30
31 typedef struct {
32 AVClass *class;
33 int sample_rate;
34 } GSMDemuxerContext;
35
36 static int gsm_read_packet(AVFormatContext *s, AVPacket *pkt)
37 {
38 int ret, size;
39
40 size = GSM_BLOCK_SIZE * 32;
41
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;
51 pkt->duration = ret / GSM_BLOCK_SIZE;
52 pkt->pts = pkt->pos / GSM_BLOCK_SIZE;
53
54 return 0;
55 }
56
57 static 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;
68 st->codec->block_align = GSM_BLOCK_SIZE;
69 st->codec->bit_rate = GSM_BLOCK_SIZE * 8 * c->sample_rate / GSM_BLOCK_SAMPLES;
70
71 avpriv_set_pts_info(st, 64, GSM_BLOCK_SAMPLES, GSM_SAMPLE_RATE);
72
73 return 0;
74 }
75
76 static int gsm_read_seek2(AVFormatContext *s, int stream_index, int64_t min_ts,
77 int64_t ts, int64_t max_ts, int flags)
78 {
79 GSMDemuxerContext *c = s->priv_data;
80
81 /* convert timestamps to file positions */
82 if (!(flags & AVSEEK_FLAG_BYTE)) {
83 if (stream_index < 0) {
84 AVRational bitrate_q = { GSM_BLOCK_SAMPLES, c->sample_rate * GSM_BLOCK_SIZE };
85 ts = av_rescale_q(ts, AV_TIME_BASE_Q, bitrate_q);
86 min_ts = av_rescale_q(min_ts, AV_TIME_BASE_Q, bitrate_q);
87 max_ts = av_rescale_q(max_ts, AV_TIME_BASE_Q, bitrate_q);
88 } else {
89 ts *= GSM_BLOCK_SIZE;
90 min_ts *= GSM_BLOCK_SIZE;
91 max_ts *= GSM_BLOCK_SIZE;
92 }
93 }
94 /* round to nearest block boundary */
95 ts = (ts + GSM_BLOCK_SIZE / 2) / GSM_BLOCK_SIZE * GSM_BLOCK_SIZE;
96 ts = FFMAX(0, ts);
97
98 /* handle min/max */
99 while (ts < min_ts)
100 ts += GSM_BLOCK_SIZE;
101 while (ts > max_ts)
102 ts -= GSM_BLOCK_SIZE;
103 if (ts < min_ts || ts > max_ts)
104 return -1;
105
106 return avio_seek(s->pb, ts, SEEK_SET);
107 }
108
109 static const AVOption options[] = {
110 { "sample_rate", "", offsetof(GSMDemuxerContext, sample_rate),
111 AV_OPT_TYPE_INT, {.dbl = GSM_SAMPLE_RATE}, 1, INT_MAX / GSM_BLOCK_SIZE,
112 AV_OPT_FLAG_DECODING_PARAM },
113 { NULL },
114 };
115
116 static const AVClass class = {
117 .class_name = "gsm demuxer",
118 .item_name = av_default_item_name,
119 .option = options,
120 .version = LIBAVUTIL_VERSION_INT,
121 };
122
123 AVInputFormat ff_gsm_demuxer = {
124 .name = "gsm",
125 .long_name = NULL_IF_CONFIG_SMALL("raw GSM"),
126 .priv_data_size = sizeof(GSMDemuxerContext),
127 .read_header = gsm_read_header,
128 .read_packet = gsm_read_packet,
129 .read_seek2 = gsm_read_seek2,
130 .extensions = "gsm",
131 .value = CODEC_ID_GSM,
132 .priv_class = &class,
133 };