yading@11: /*
yading@11:  * RAW GSM demuxer
yading@11:  * Copyright (c) 2011 Justin Ruggles
yading@11:  *
yading@11:  * This file is part of Libav.
yading@11:  *
yading@11:  * Libav is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * Libav is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with Libav; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "libavutil/channel_layout.h"
yading@11: #include "libavutil/mathematics.h"
yading@11: #include "libavutil/opt.h"
yading@11: #include "avformat.h"
yading@11: #include "internal.h"
yading@11: 
yading@11: #define GSM_BLOCK_SIZE    33
yading@11: #define GSM_BLOCK_SAMPLES 160
yading@11: #define GSM_SAMPLE_RATE   8000
yading@11: 
yading@11: typedef struct {
yading@11:     AVClass *class;
yading@11:     int sample_rate;
yading@11: } GSMDemuxerContext;
yading@11: 
yading@11: static int gsm_read_packet(AVFormatContext *s, AVPacket *pkt)
yading@11: {
yading@11:     int ret, size;
yading@11: 
yading@11:     size = GSM_BLOCK_SIZE;
yading@11: 
yading@11:     pkt->pos = avio_tell(s->pb);
yading@11:     pkt->stream_index = 0;
yading@11: 
yading@11:     ret = av_get_packet(s->pb, pkt, size);
yading@11:     if (ret < GSM_BLOCK_SIZE) {
yading@11:         av_free_packet(pkt);
yading@11:         return ret < 0 ? ret : AVERROR(EIO);
yading@11:     }
yading@11:     pkt->duration = 1;
yading@11:     pkt->pts      = pkt->pos / GSM_BLOCK_SIZE;
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int gsm_read_header(AVFormatContext *s)
yading@11: {
yading@11:     GSMDemuxerContext *c = s->priv_data;
yading@11:     AVStream *st = avformat_new_stream(s, NULL);
yading@11:     if (!st)
yading@11:         return AVERROR(ENOMEM);
yading@11: 
yading@11:     st->codec->codec_type  = AVMEDIA_TYPE_AUDIO;
yading@11:     st->codec->codec_id    = s->iformat->raw_codec_id;
yading@11:     st->codec->channels    = 1;
yading@11:     st->codec->channel_layout = AV_CH_LAYOUT_MONO;
yading@11:     st->codec->sample_rate = c->sample_rate;
yading@11:     st->codec->bit_rate    = GSM_BLOCK_SIZE * 8 * c->sample_rate / GSM_BLOCK_SAMPLES;
yading@11: 
yading@11:     avpriv_set_pts_info(st, 64, GSM_BLOCK_SAMPLES, GSM_SAMPLE_RATE);
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static const AVOption options[] = {
yading@11:     { "sample_rate", "", offsetof(GSMDemuxerContext, sample_rate),
yading@11:        AV_OPT_TYPE_INT, {.i64 = GSM_SAMPLE_RATE}, 1, INT_MAX / GSM_BLOCK_SIZE,
yading@11:        AV_OPT_FLAG_DECODING_PARAM },
yading@11:     { NULL },
yading@11: };
yading@11: 
yading@11: static const AVClass class = {
yading@11:     .class_name = "gsm demuxer",
yading@11:     .item_name  = av_default_item_name,
yading@11:     .option     = options,
yading@11:     .version    = LIBAVUTIL_VERSION_INT,
yading@11: };
yading@11: 
yading@11: AVInputFormat ff_gsm_demuxer = {
yading@11:     .name           = "gsm",
yading@11:     .long_name      = NULL_IF_CONFIG_SMALL("raw GSM"),
yading@11:     .priv_data_size = sizeof(GSMDemuxerContext),
yading@11:     .read_header    = gsm_read_header,
yading@11:     .read_packet    = gsm_read_packet,
yading@11:     .flags          = AVFMT_GENERIC_INDEX,
yading@11:     .extensions     = "gsm",
yading@11:     .raw_codec_id   = AV_CODEC_ID_GSM,
yading@11:     .priv_class     = &class,
yading@11: };