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https://github.com/FFmpeg/FFmpeg.git
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104 lines
3.0 KiB
C
104 lines
3.0 KiB
C
/*
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* RAW AC-3 and E-AC-3 demuxer
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* Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/crc.h"
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#include "libavcodec/ac3_parser.h"
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#include "avformat.h"
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#include "rawdec.h"
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static int ac3_eac3_probe(AVProbeData *p, enum CodecID expected_codec_id)
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{
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int max_frames, first_frames = 0, frames;
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uint8_t *buf, *buf2, *end;
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AC3HeaderInfo hdr;
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GetBitContext gbc;
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enum CodecID codec_id = CODEC_ID_AC3;
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max_frames = 0;
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buf = p->buf;
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end = buf + p->buf_size;
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for(; buf < end; buf++) {
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buf2 = buf;
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for(frames = 0; buf2 < end; frames++) {
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init_get_bits(&gbc, buf2, 54);
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if(ff_ac3_parse_header(&gbc, &hdr) < 0)
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break;
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if(buf2 + hdr.frame_size > end ||
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av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf2 + 2, hdr.frame_size - 2))
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break;
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if (hdr.bitstream_id > 10)
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codec_id = CODEC_ID_EAC3;
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buf2 += hdr.frame_size;
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}
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max_frames = FFMAX(max_frames, frames);
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if(buf == p->buf)
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first_frames = frames;
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}
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if(codec_id != expected_codec_id) return 0;
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// keep this in sync with mp3 probe, both need to avoid
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// issues with MPEG-files!
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if (first_frames>=4) return AVPROBE_SCORE_MAX/2+1;
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else if(max_frames>500)return AVPROBE_SCORE_MAX/2;
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else if(max_frames>=4) return AVPROBE_SCORE_MAX/4;
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else if(max_frames>=1) return 1;
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else return 0;
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}
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#if CONFIG_AC3_DEMUXER
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static int ac3_probe(AVProbeData *p)
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{
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return ac3_eac3_probe(p, CODEC_ID_AC3);
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}
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AVInputFormat ac3_demuxer = {
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"ac3",
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NULL_IF_CONFIG_SMALL("raw AC-3"),
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0,
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ac3_probe,
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ff_raw_audio_read_header,
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ff_raw_read_partial_packet,
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.flags= AVFMT_GENERIC_INDEX,
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.extensions = "ac3",
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.value = CODEC_ID_AC3,
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};
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#endif
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#if CONFIG_EAC3_DEMUXER
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static int eac3_probe(AVProbeData *p)
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{
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return ac3_eac3_probe(p, CODEC_ID_EAC3);
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}
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AVInputFormat eac3_demuxer = {
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"eac3",
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NULL_IF_CONFIG_SMALL("raw E-AC-3"),
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0,
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eac3_probe,
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ff_raw_audio_read_header,
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ff_raw_read_partial_packet,
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.flags= AVFMT_GENERIC_INDEX,
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.extensions = "eac3",
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.value = CODEC_ID_EAC3,
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};
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#endif
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