CD+G demuxer and decoder

Patch by Michael Tison (gmail address: blackspike@....)

Originally committed as revision 20890 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/cdg.c

@@ -0,0 +1,66 @@
+/*
+ * 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"
+
+#define CDG_PACKET_SIZE    24
+
+static int read_header(AVFormatContext *s, AVFormatParameters *ap)
+{
+    AVStream *vst;
+    int ret;
+
+    vst = av_new_stream(s, 0);
+    if (!vst)
+        return AVERROR(ENOMEM);
+
+    vst->codec->codec_type = CODEC_TYPE_VIDEO;
+    vst->codec->codec_id   = CODEC_ID_CDGRAPHICS;
+
+    /// 75 sectors/sec * 4 packets/sector = 300 packets/sec
+    av_set_pts_info(vst, 32, 1, 300);
+
+    ret = url_fsize(s->pb);
+    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;
+
+    ret = av_get_packet(s->pb, pkt, CDG_PACKET_SIZE);
+
+    pkt->stream_index = 0;
+    return ret;
+}
+
+AVInputFormat cdg_demuxer = {
+    "cdg",
+    NULL_IF_CONFIG_SMALL("CD Graphics Format"),
+    0,
+    NULL,
+    read_header,
+    read_packet,
+    .extensions = "cdg"
+};