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/*
* Raw AC-4 muxer
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavcodec/codec_id.h"
#include "libavcodec/codec_par.h"
#include "libavcodec/packet.h"
#include "libavutil/crc.h"
#include "libavutil/opt.h"
#include "avformat.h"
#include "mux.h"
typedef struct AC4Context {
AVClass *class;
int write_crc;
} AC4Context;
static int ac4_init(AVFormatContext *s)
{
AVCodecParameters *par = s->streams[0]->codecpar;
if (s->nb_streams != 1 || par->codec_id != AV_CODEC_ID_AC4) {
av_log(s, AV_LOG_ERROR, "Only one AC-4 stream can be muxed by the AC-4 muxer\n");
return AVERROR(EINVAL);
}
return 0;
}
static int ac4_write_packet(AVFormatContext *s, AVPacket *pkt)
{
AC4Context *ac4 = s->priv_data;
AVIOContext *pb = s->pb;
if (!pkt->size)
return 0;
if (ac4->write_crc)
avio_wb16(pb, 0xAC41);
else
avio_wb16(pb, 0xAC40);
if (pkt->size >= 0xffff) {
avio_wb16(pb, 0xffff);
avio_wb24(pb, pkt->size);
} else {
avio_wb16(pb, pkt->size);
}
avio_write(pb, pkt->data, pkt->size);
if (ac4->write_crc) {
uint16_t crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, pkt->data, pkt->size);
avio_wl16(pb, crc);
}
return 0;
}
#define ENC AV_OPT_FLAG_ENCODING_PARAM
#define OFFSET(obj) offsetof(AC4Context, obj)
static const AVOption ac4_options[] = {
{ "write_crc", "enable checksum", OFFSET(write_crc), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, ENC},
{ NULL },
};
static const AVClass ac4_muxer_class = {
.class_name = "AC4 muxer",
.option = ac4_options,
.version = LIBAVUTIL_VERSION_INT,
};
const FFOutputFormat ff_ac4_muxer = {
.p.name = "ac4",
.p.long_name = NULL_IF_CONFIG_SMALL("raw AC-4"),
.p.mime_type = "audio/ac4",
.p.extensions = "ac4",
.priv_data_size = sizeof(AC4Context),
.p.audio_codec = AV_CODEC_ID_AC4,
.p.video_codec = AV_CODEC_ID_NONE,
.init = ac4_init,
.write_packet = ac4_write_packet,
.p.priv_class = &ac4_muxer_class,
.p.flags = AVFMT_NOTIMESTAMPS,
};
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