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107 lines
2.7 KiB
107 lines
2.7 KiB
/* |
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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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if (left < size) |
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break; |
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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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