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/*
* RAW AC-3 and E-AC-3 demuxer
* Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com>
*
* 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 "config_components.h"
#include "libavutil/avassert.h"
#include "libavutil/crc.h"
#include "libavcodec/ac3_parser.h"
#include "avformat.h"
#include "demux.h"
#include "rawdec.h"
static int ac3_eac3_probe(const AVProbeData *p, enum AVCodecID expected_codec_id)
{
int max_frames, first_frames = 0, frames;
const uint8_t *buf, *buf2, *end;
enum AVCodecID codec_id = AV_CODEC_ID_AC3;
max_frames = 0;
buf = p->buf;
end = buf + p->buf_size;
for(; buf < end; buf++) {
if(buf > p->buf && !(buf[0] == 0x0B && buf[1] == 0x77)
&& !(buf[0] == 0x77 && buf[1] == 0x0B) )
continue;
buf2 = buf;
for(frames = 0; buf2 < end; frames++) {
uint8_t buf3[4096];
uint8_t bitstream_id;
uint16_t frame_size;
int i, ret;
if(!memcmp(buf2, "\x1\x10", 2)) {
if (buf2 + 16 > end)
break;
buf2+=16;
}
if (buf[0] == 0x77 && buf[1] == 0x0B) {
for(i=0; i<8; i+=2) {
buf3[i ] = buf2[i+1];
buf3[i+1] = buf2[i ];
}
ret = av_ac3_parse_header(buf3, 8, &bitstream_id,
&frame_size);
}else
ret = av_ac3_parse_header(buf2, end - buf2, &bitstream_id,
&frame_size);
if (ret < 0)
break;
if(buf2 + frame_size > end)
break;
if (buf[0] == 0x77 && buf[1] == 0x0B) {
av_assert0(frame_size <= sizeof(buf3));
for(i = 8; i < frame_size; i += 2) {
buf3[i ] = buf2[i+1];
buf3[i+1] = buf2[i ];
}
if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf3 + 2, frame_size - 2))
break;
} else {
if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf2 + 2, frame_size - 2))
break;
}
if (bitstream_id > 10)
codec_id = AV_CODEC_ID_EAC3;
buf2 += frame_size;
}
max_frames = FFMAX(max_frames, frames);
if(buf == p->buf)
first_frames = frames;
}
if(codec_id != expected_codec_id) return 0;
// keep this in sync with mp3 probe, both need to avoid
// issues with MPEG-files!
if (first_frames>=7) return AVPROBE_SCORE_EXTENSION + 1;
else if(max_frames>200)return AVPROBE_SCORE_EXTENSION;
else if(max_frames>=4) return AVPROBE_SCORE_EXTENSION/2;
else if(max_frames>=1) return 1;
else return 0;
}
#if CONFIG_AC3_DEMUXER
static int ac3_probe(const AVProbeData *p)
{
return ac3_eac3_probe(p, AV_CODEC_ID_AC3);
}
const FFInputFormat ff_ac3_demuxer = {
.p.name = "ac3",
.p.long_name = NULL_IF_CONFIG_SMALL("raw AC-3"),
.p.flags = AVFMT_GENERIC_INDEX,
.p.extensions = "ac3",
.p.priv_class = &ff_raw_demuxer_class,
.read_probe = ac3_probe,
.read_header = ff_raw_audio_read_header,
.read_packet = ff_raw_read_partial_packet,
.raw_codec_id = AV_CODEC_ID_AC3,
.priv_data_size = sizeof(FFRawDemuxerContext),
};
#endif
#if CONFIG_EAC3_DEMUXER
static int eac3_probe(const AVProbeData *p)
{
return ac3_eac3_probe(p, AV_CODEC_ID_EAC3);
}
const FFInputFormat ff_eac3_demuxer = {
.p.name = "eac3",
.p.long_name = NULL_IF_CONFIG_SMALL("raw E-AC-3"),
.p.flags = AVFMT_GENERIC_INDEX,
.p.extensions = "eac3,ec3",
.p.priv_class = &ff_raw_demuxer_class,
.read_probe = eac3_probe,
.read_header = ff_raw_audio_read_header,
.read_packet = ff_raw_read_partial_packet,
.raw_codec_id = AV_CODEC_ID_EAC3,
.priv_data_size = sizeof(FFRawDemuxerContext),
};
#endif
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