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