3 * Copyright (c) 2011 Justin Ruggles
5 * This file is part of Libav.
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.
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.
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
22 #include "libavutil/channel_layout.h"
23 #include "libavutil/mathematics.h"
24 #include "libavutil/opt.h"
28 #define GSM_BLOCK_SIZE 33
29 #define GSM_BLOCK_SAMPLES 160
30 #define GSM_SAMPLE_RATE 8000
32 typedef struct GSMDemuxerContext {
37 static int gsm_read_packet(AVFormatContext *s, AVPacket *pkt)
41 size = GSM_BLOCK_SIZE;
43 pkt->pos = avio_tell(s->pb);
44 pkt->stream_index = 0;
46 ret = av_get_packet(s->pb, pkt, size);
47 if (ret < GSM_BLOCK_SIZE) {
49 return ret < 0 ? ret : AVERROR(EIO);
53 pkt->pts = pkt->pos / GSM_BLOCK_SIZE;
58 static int gsm_read_header(AVFormatContext *s)
60 GSMDemuxerContext *c = s->priv_data;
61 AVStream *st = avformat_new_stream(s, NULL);
63 return AVERROR(ENOMEM);
65 st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
66 st->codecpar->codec_id = s->iformat->raw_codec_id;
67 st->codecpar->channels = 1;
68 st->codecpar->channel_layout = AV_CH_LAYOUT_MONO;
69 st->codecpar->sample_rate = c->sample_rate;
70 st->codecpar->bit_rate = GSM_BLOCK_SIZE * 8 * c->sample_rate / GSM_BLOCK_SAMPLES;
72 avpriv_set_pts_info(st, 64, GSM_BLOCK_SAMPLES, GSM_SAMPLE_RATE);
77 static const AVOption options[] = {
78 { "sample_rate", "", offsetof(GSMDemuxerContext, sample_rate),
79 AV_OPT_TYPE_INT, {.i64 = GSM_SAMPLE_RATE}, 1, INT_MAX / GSM_BLOCK_SIZE,
80 AV_OPT_FLAG_DECODING_PARAM },
84 static const AVClass class = {
85 .class_name = "gsm demuxer",
86 .item_name = av_default_item_name,
88 .version = LIBAVUTIL_VERSION_INT,
91 AVInputFormat ff_gsm_demuxer = {
93 .long_name = NULL_IF_CONFIG_SMALL("raw GSM"),
94 .priv_data_size = sizeof(GSMDemuxerContext),
95 .read_header = gsm_read_header,
96 .read_packet = gsm_read_packet,
97 .flags = AVFMT_GENERIC_INDEX,
99 .raw_codec_id = AV_CODEC_ID_GSM,
100 .priv_class = &class,