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