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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 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/crc.h"
#include "libavcodec/ac3_parser.h"
#include "avformat.h"
#include "rawdec.h"
static int ac3_eac3_probe(AVProbeData *p, enum AVCodecID expected_codec_id)
{
int max_frames, first_frames = 0, frames;
uint8_t *buf, *buf2, *end;
AC3HeaderInfo hdr;
GetBitContext gbc;
enum AVCodecID codec_id = AV_CODEC_ID_AC3;
max_frames = 0;
buf = p->buf;
end = buf + p->buf_size;
for(; buf < end; buf++) {
buf2 = buf;
for(frames = 0; buf2 < end; frames++) {
init_get_bits(&gbc, buf2, 54);
if(avpriv_ac3_parse_header(&gbc, &hdr) < 0)
break;
if(buf2 + hdr.frame_size > end ||
av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf2 + 2, hdr.frame_size - 2))
break;
if (hdr.bitstream_id > 10)
codec_id = AV_CODEC_ID_EAC3;
buf2 += hdr.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 >= 4) return AVPROBE_SCORE_MAX / 2 + 1;
if (max_frames) {
int pes = 0, i;
unsigned int code = -1;
#define VIDEO_ID 0x000001e0
#define AUDIO_ID 0x000001c0
/* do a search for mpegps headers to be able to properly bias
* towards mpegps if we detect this stream as both. */
for (i = 0; i<p->buf_size; i++) {
code = (code << 8) + p->buf[i];
if ((code & 0xffffff00) == 0x100) {
if ((code & 0x1f0) == VIDEO_ID) pes++;
else if((code & 0x1e0) == AUDIO_ID) pes++;
}
}
if (pes)
max_frames = (max_frames + pes - 1) / pes;
}
if (max_frames > 500) return AVPROBE_SCORE_MAX / 2;
else if (max_frames >= 4) return AVPROBE_SCORE_MAX / 4;
else if (max_frames >= 1) return 1;
else return 0;
}
#if CONFIG_AC3_DEMUXER
static int ac3_probe(AVProbeData *p)
{
return ac3_eac3_probe(p, AV_CODEC_ID_AC3);
}
AVInputFormat ff_ac3_demuxer = {
.name = "ac3",
.long_name = NULL_IF_CONFIG_SMALL("raw AC-3"),
.read_probe = ac3_probe,
.read_header = ff_raw_audio_read_header,
.read_packet = ff_raw_read_partial_packet,
.flags= AVFMT_GENERIC_INDEX,
.extensions = "ac3",
.raw_codec_id = AV_CODEC_ID_AC3,
};
#endif
#if CONFIG_EAC3_DEMUXER
static int eac3_probe(AVProbeData *p)
{
return ac3_eac3_probe(p, AV_CODEC_ID_EAC3);
}
AVInputFormat ff_eac3_demuxer = {
.name = "eac3",
.long_name = NULL_IF_CONFIG_SMALL("raw E-AC-3"),
.read_probe = eac3_probe,
.read_header = ff_raw_audio_read_header,
.read_packet = ff_raw_read_partial_packet,
.flags = AVFMT_GENERIC_INDEX,
.extensions = "eac3",
.raw_codec_id = AV_CODEC_ID_EAC3,
};
#endif
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