[FFmpeg-devel] [PATCH] add Falcom Xanadu demuxer

[James Darnley]

---
 libavformat/Makefile     |  1 +
 libavformat/allformats.c |  1 +
 libavformat/falcom_xa.c  | 98 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 100 insertions(+)
 create mode 100644 libavformat/falcom_xa.c

diff --git a/libavformat/Makefile b/libavformat/Makefile
index 6bdfbe6789..06b6b5da57 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -158,6 +158,7 @@ OBJS-$(CONFIG_EA_DEMUXER)                += electronicarts.o
 OBJS-$(CONFIG_EAC3_DEMUXER)              += ac3dec.o rawdec.o
 OBJS-$(CONFIG_EAC3_MUXER)                += rawenc.o
 OBJS-$(CONFIG_EPAF_DEMUXER)              += epafdec.o pcm.o
+OBJS-$(CONFIG_FALCOM_XA_DEMUXER)         += falcom_xa.o
 OBJS-$(CONFIG_FFM_DEMUXER)               += ffmdec.o
 OBJS-$(CONFIG_FFM_MUXER)                 += ffmenc.o
 OBJS-$(CONFIG_FFMETADATA_DEMUXER)        += ffmetadec.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 09e62c3cfc..0c23ea9df0 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -117,6 +117,7 @@ static void register_all(void)
     REGISTER_MUXDEMUX(EAC3,             eac3);
     REGISTER_DEMUXER (EPAF,             epaf);
     REGISTER_MUXER   (F4V,              f4v);
+    REGISTER_DEMUXER (FALCOM_XA,        falcom_xa);
     REGISTER_MUXDEMUX(FFM,              ffm);
     REGISTER_MUXDEMUX(FFMETADATA,       ffmetadata);
     REGISTER_MUXER   (FIFO,             fifo);
diff --git a/libavformat/falcom_xa.c b/libavformat/falcom_xa.c
new file mode 100644
index 0000000000..4c5f32a1b6
--- /dev/null
+++ b/libavformat/falcom_xa.c
@@ -0,0 +1,98 @@
+/*
+ * Falcom Xanadu demuxer
+ * Copyright (c) 2016 James Darnley
+ *
+ * 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"
+
+typedef struct FalcomXADemuxContext {
+    const AVClass *class;
+    unsigned frame_size;
+} FalcomXADemuxContext;
+
+static av_cold
+int falcom_xa_read_header(AVFormatContext *s)
+{
+    int sample_rate, bit_depth, channels;
+    AVStream *st;
+    AVIOContext *pb = s->pb;
+
+    avio_seek(pb, 22, SEEK_SET);
+    channels = avio_rl16(pb);
+    if (channels != 2)
+        return AVERROR_INVALIDDATA;
+
+    sample_rate = avio_rl32(pb);
+    if (sample_rate != 44100)
+        return AVERROR_INVALIDDATA;
+
+    avio_seek(pb, 34, SEEK_SET);
+    bit_depth = avio_rl16(pb);
+    if (bit_depth != 16)
+        return AVERROR_INVALIDDATA;
+
+    avio_seek(pb, 44, SEEK_SET);
+
+    st = avformat_new_stream(s, NULL);
+    if (!st)
+        return AVERROR(ENOMEM);
+
+    st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
+    st->codecpar->codec_id = AV_CODEC_ID_ADPCM_MS;
+    st->codecpar->sample_rate = sample_rate;
+    st->codecpar->channels = channels;
+    st->codecpar->block_align = 2048;
+
+    return 0;
+}
+
+static
+int falcom_xa_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    FalcomXADemuxContext *ctx = s->priv_data;
+
+    if (ctx->frame_size == 0) {
+        unsigned tell = avio_tell(s->pb);
+        unsigned size = avio_rl32(s->pb);
+        av_log(ctx, AV_LOG_DEBUG, "read size %u (0x%x) at offset %u (0x%x)\n",
+                size, size, tell, tell);
+        if (size % 2048)
+            return AVERROR_INVALIDDATA;
+        ctx->frame_size = size;
+        avio_skip(s->pb, 4); // unknown bytes
+    }
+
+    ctx->frame_size -= 2048;
+    return av_get_packet(s->pb, pkt, 2048);
+}
+
+static const AVClass falcom_xa_demux_class = {
+    .class_name = "Falcom Xanadu demuxer",
+    .item_name  = av_default_item_name,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVInputFormat ff_falcom_xa_demuxer = {
+    .name           = "falcom_xa",
+    .long_name      = NULL_IF_CONFIG_SMALL("Falcom Xanadu demuxer"),
+    .priv_data_size = sizeof(FalcomXADemuxContext),
+    .read_header    = falcom_xa_read_header,
+    .read_packet    = falcom_xa_read_packet,
+    .priv_class     = &falcom_xa_demux_class,
+};
-- 
2.12.2