cdg.c 1.96 KB
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/*
 * CD Graphics Demuxer
 * Copyright (c) 2009 Michael Tison
 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * 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.
 *
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 * Libav is distributed in the hope that it will be useful,
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 * 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
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "avformat.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
#define CDG_MASK           0x3F
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static int read_header(AVFormatContext *s)
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{
    AVStream *vst;
    int ret;

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    vst = avformat_new_stream(s, NULL);
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    if (!vst)
        return AVERROR(ENOMEM);

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    vst->codec->codec_type = AVMEDIA_TYPE_VIDEO;
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    vst->codec->codec_id   = CODEC_ID_CDGRAPHICS;

    /// 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)
        vst->duration = (ret * vst->time_base.den) / (CDG_PACKET_SIZE * 300);

    return 0;
}

static int read_packet(AVFormatContext *s, AVPacket *pkt)
{
    int ret;

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    while (1) {
        ret = av_get_packet(s->pb, pkt, CDG_PACKET_SIZE);
        if (ret < 1 || (pkt->data[0] & CDG_MASK) == CDG_COMMAND)
            break;
        av_free_packet(pkt);
    }
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    pkt->stream_index = 0;
    return ret;
}

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AVInputFormat ff_cdg_demuxer = {
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    .name           = "cdg",
    .long_name      = NULL_IF_CONFIG_SMALL("CD Graphics Format"),
    .read_header    = read_header,
    .read_packet    = read_packet,
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    .extensions = "cdg"
};