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https://github.com/FFmpeg/FFmpeg.git
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96 lines
2.7 KiB
C
96 lines
2.7 KiB
C
/*
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* CD Graphics Demuxer
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* Copyright (c) 2009 Michael Tison
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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 "avformat.h"
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#include "demux.h"
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#include "internal.h"
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#define CDG_PACKET_SIZE 24
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#define CDG_COMMAND 0x09
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#define CDG_MASK 0x3F
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static int read_probe(const AVProbeData *p)
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{
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const int cnt = p->buf_size / CDG_PACKET_SIZE;
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int score = 0;
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for (int i = 0; i < cnt; i++) {
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const int x = p->buf[i * CDG_PACKET_SIZE] & CDG_MASK;
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score += x == CDG_COMMAND;
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if (x != CDG_COMMAND && x != 0)
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return 0;
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}
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return FFMIN(score, AVPROBE_SCORE_MAX);
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}
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static int read_header(AVFormatContext *s)
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{
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AVStream *vst;
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int64_t ret;
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vst = avformat_new_stream(s, NULL);
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if (!vst)
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return AVERROR(ENOMEM);
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vst->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
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vst->codecpar->codec_id = AV_CODEC_ID_CDGRAPHICS;
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/// 75 sectors/sec * 4 packets/sector = 300 packets/sec
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avpriv_set_pts_info(vst, 32, 1, 300);
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ret = avio_size(s->pb);
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if (ret < 0) {
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av_log(s, AV_LOG_WARNING, "Cannot calculate duration as file size cannot be determined\n");
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} else
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vst->duration = (ret * (int64_t)vst->time_base.den) / (CDG_PACKET_SIZE * 300);
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return 0;
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}
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static int read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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int ret;
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ret = av_get_packet(s->pb, pkt, CDG_PACKET_SIZE);
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pkt->stream_index = 0;
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pkt->dts=
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pkt->pts= pkt->pos / CDG_PACKET_SIZE;
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if (!pkt->pos || (ret > 5 &&
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(pkt->data[0] & CDG_MASK) == CDG_COMMAND &&
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(pkt->data[1] & CDG_MASK) == 1 && !(pkt->data[2+2+1] & 0x0F))) {
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pkt->flags = AV_PKT_FLAG_KEY;
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}
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return ret;
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}
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const FFInputFormat ff_cdg_demuxer = {
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.p.name = "cdg",
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.p.long_name = NULL_IF_CONFIG_SMALL("CD Graphics"),
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.p.flags = AVFMT_GENERIC_INDEX,
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.p.extensions = "cdg",
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.read_probe = read_probe,
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.read_header = read_header,
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.read_packet = read_packet,
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};
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