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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 "libavutil/crc.h"
#include "libavcodec/ac3_parser.h"
#include "avformat.h" |
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#include "rawdec.h" |
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|
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static int ac3_eac3_probe(AVProbeData *p, enum AVCodecID expected_codec_id) |
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{
int max_frames, first_frames = 0, frames; |
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const uint8_t *buf, *buf2, *end; |
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AC3HeaderInfo *phdr = NULL; |
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GetBitContext gbc; |
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enum AVCodecID codec_id = AV_CODEC_ID_AC3; |
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max_frames = 0;
buf = p->buf;
end = buf + p->buf_size;
for(; buf < end; buf++) { |
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if(buf > p->buf && !(buf[0] == 0x0B && buf[1] == 0x77)
&& !(buf[0] == 0x77 && buf[1] == 0x0B) ) |
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continue; |
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buf2 = buf;
for(frames = 0; buf2 < end; frames++) { |
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uint8_t buf3[4096];
int i; |
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if(!memcmp(buf2, "\x1\x10\0\0\0\0\0\0", 8))
buf2+=16; |
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if (buf[0] == 0x77 && buf[1] == 0x0B) {
for(i=0; i<8; i+=2) {
buf3[i ] = buf[i+1];
buf3[i+1] = buf[i ];
}
init_get_bits(&gbc, buf3, 54);
}else
init_get_bits(&gbc, buf2, 54); |
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if(avpriv_ac3_parse_header2(&gbc, &phdr) < 0) |
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break; |
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if(buf2 + phdr->frame_size > end) |
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break;
if (buf[0] == 0x77 && buf[1] == 0x0B) { |
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av_assert0(phdr->frame_size <= sizeof(buf3));
for(i=8; i<phdr->frame_size; i+=2) { |
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buf3[i ] = buf[i+1];
buf3[i+1] = buf[i ];
}
} |
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if(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, gbc.buffer + 2, phdr->frame_size - 2)) |
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break; |
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if (phdr->bitstream_id > 10) |
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codec_id = AV_CODEC_ID_EAC3; |
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buf2 += phdr->frame_size; |
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}
max_frames = FFMAX(max_frames, frames);
if(buf == p->buf)
first_frames = frames;
} |
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av_freep(&phdr); |
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if(codec_id != expected_codec_id) return 0;
// keep this in sync with mp3 probe, both need to avoid
// issues with MPEG-files! |
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if (first_frames>=4) return AVPROBE_SCORE_EXTENSION + 1;
else if(max_frames>200)return AVPROBE_SCORE_EXTENSION;
else if(max_frames>=4) return AVPROBE_SCORE_EXTENSION/2; |
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else if(max_frames>=1) return 1;
else return 0;
}
#if CONFIG_AC3_DEMUXER
static int ac3_probe(AVProbeData *p)
{ |
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return ac3_eac3_probe(p, AV_CODEC_ID_AC3); |
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}
|
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AVInputFormat ff_ac3_demuxer = { |
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.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, |
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.flags= AVFMT_GENERIC_INDEX,
.extensions = "ac3", |
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.raw_codec_id = AV_CODEC_ID_AC3, |
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};
#endif
#if CONFIG_EAC3_DEMUXER
static int eac3_probe(AVProbeData *p)
{ |
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return ac3_eac3_probe(p, AV_CODEC_ID_EAC3); |
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}
|
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AVInputFormat ff_eac3_demuxer = { |
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.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, |
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.flags = AVFMT_GENERIC_INDEX,
.extensions = "eac3", |
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.raw_codec_id = AV_CODEC_ID_EAC3, |
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};
#endif |