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/*
* RAW AC-4 demuxer
* Copyright (c) 2019 Paul B Mahol
*
* 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 "libavutil/avassert.h"
#include "libavutil/crc.h"
#include "avformat.h"
#include "demux.h"
#include "rawdec.h"
static int ac4_probe(const AVProbeData *p)
{
const uint8_t *buf = p->buf;
int left = p->buf_size;
int max_frames = 0;
while (left > 7) {
int size;
if (buf[0] == 0xAC &&
(buf[1] == 0x40 ||
buf[1] == 0x41)) {
size = (buf[2] << 8) | buf[3];
if (size == 0xFFFF)
size = 3 + ((buf[4] << 16) | (buf[5] << 8) | buf[6]);
size += 4;
if (buf[1] == 0x41)
size += 2;
if (left < size)
break;
max_frames++;
left -= size;
buf += size;
} else {
break;
}
}
return FFMIN(AVPROBE_SCORE_MAX, max_frames * 7);
}
static int ac4_read_header(AVFormatContext *s)
{
AVStream *st;
st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
st->codecpar->codec_id = AV_CODEC_ID_AC4;
return 0;
}
static int ac4_read_packet(AVFormatContext *s, AVPacket *pkt)
{
AVIOContext *pb = s->pb;
int64_t pos;
uint16_t sync;
int ret, size;
if (avio_feof(s->pb))
return AVERROR_EOF;
pos = avio_tell(s->pb);
sync = avio_rb16(pb);
size = avio_rb16(pb);
if (size == 0xffff)
size = avio_rb24(pb);
ret = av_get_packet(pb, pkt, size);
pkt->pos = pos;
pkt->stream_index = 0;
if (sync == 0xAC41)
avio_skip(pb, 2);
return ret;
}
const FFInputFormat ff_ac4_demuxer = {
.p.name = "ac4",
.p.long_name = NULL_IF_CONFIG_SMALL("raw AC-4"),
.p.flags = AVFMT_GENERIC_INDEX,
.p.extensions = "ac4",
.read_probe = ac4_probe,
.read_header = ac4_read_header,
.read_packet = ac4_read_packet,
};
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