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/*
* RAW GSM demuxer
* Copyright (c) 2011 Justin Ruggles
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/mathematics.h"
#include "libavutil/opt.h"
#include "avformat.h"
#define GSM_BLOCK_SIZE 33
#define GSM_BLOCK_SAMPLES 160
#define GSM_SAMPLE_RATE 8000
typedef struct {
AVClass *class;
int sample_rate;
} GSMDemuxerContext;
static int gsm_read_packet(AVFormatContext *s, AVPacket *pkt)
{
int ret, size;
size = GSM_BLOCK_SIZE * 32;
if (av_new_packet(pkt, size) < 0)
return AVERROR(ENOMEM);
pkt->pos = avio_tell(s->pb);
pkt->stream_index = 0;
ret = av_get_packet(s->pb, pkt, size);
if (ret < GSM_BLOCK_SIZE) {
av_free_packet(pkt);
return ret < 0 ? ret : AVERROR(EIO);
}
pkt->size = ret;
pkt->duration = ret / GSM_BLOCK_SIZE;
pkt->pts = pkt->pos / GSM_BLOCK_SIZE;
return 0;
}
static int gsm_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
GSMDemuxerContext *c = s->priv_data;
AVStream *st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
st->codec->codec_id = s->iformat->value;
st->codec->channels = 1;
st->codec->sample_rate = c->sample_rate;
st->codec->block_align = GSM_BLOCK_SIZE;
st->codec->bit_rate = GSM_BLOCK_SIZE * 8 * c->sample_rate / GSM_BLOCK_SAMPLES;
av_set_pts_info(st, 64, GSM_BLOCK_SAMPLES, GSM_SAMPLE_RATE);
return 0;
}
static int gsm_read_seek2(AVFormatContext *s, int stream_index, int64_t min_ts,
int64_t ts, int64_t max_ts, int flags)
{
GSMDemuxerContext *c = s->priv_data;
/* convert timestamps to file positions */
if (!(flags & AVSEEK_FLAG_BYTE)) {
if (stream_index < 0) {
AVRational bitrate_q = { GSM_BLOCK_SAMPLES, c->sample_rate * GSM_BLOCK_SIZE };
ts = av_rescale_q(ts, AV_TIME_BASE_Q, bitrate_q);
min_ts = av_rescale_q(min_ts, AV_TIME_BASE_Q, bitrate_q);
max_ts = av_rescale_q(max_ts, AV_TIME_BASE_Q, bitrate_q);
} else {
ts *= GSM_BLOCK_SIZE;
min_ts *= GSM_BLOCK_SIZE;
max_ts *= GSM_BLOCK_SIZE;
}
}
/* round to nearest block boundary */
ts = (ts + GSM_BLOCK_SIZE / 2) / GSM_BLOCK_SIZE * GSM_BLOCK_SIZE;
ts = FFMAX(0, ts);
/* handle min/max */
while (ts < min_ts)
ts += GSM_BLOCK_SIZE;
while (ts > max_ts)
ts -= GSM_BLOCK_SIZE;
if (ts < min_ts || ts > max_ts)
return -1;
return avio_seek(s->pb, ts, SEEK_SET);
}
static const AVOption options[] = {
{ "sample_rate", "", offsetof(GSMDemuxerContext, sample_rate),
AV_OPT_TYPE_INT, {.dbl = GSM_SAMPLE_RATE}, 1, INT_MAX / GSM_BLOCK_SIZE,
AV_OPT_FLAG_DECODING_PARAM },
{ NULL },
};
static const AVClass class = {
.class_name = "gsm demuxer",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
AVInputFormat ff_gsm_demuxer = {
.name = "gsm",
.long_name = NULL_IF_CONFIG_SMALL("raw GSM"),
.priv_data_size = sizeof(GSMDemuxerContext),
.read_header = gsm_read_header,
.read_packet = gsm_read_packet,
.read_seek2 = gsm_read_seek2,
.extensions = "gsm",
.value = CODEC_ID_GSM,
.priv_class = &class,
};
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