oggdec: Parse skeleton to determine the start time of each stream

Originally committed as revision 22457 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 85 insertions, 0 deletions

diff --git a/libavformat/oggparseskeleton.c b/libavformat/oggparseskeleton.c
new file mode 100644
index 0000000000..a3a5f75d15
--- /dev/null
+++ b/libavformat/oggparseskeleton.c
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2010 David Conrad
+ *
+ * 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 "libavcodec/bytestream.h"
+#include "avformat.h"
+#include "oggdec.h"
+
+static int skeleton_header(AVFormatContext *s, int idx)
+{
+    struct ogg *ogg = s->priv_data;
+    struct ogg_stream *os = ogg->streams + idx;
+    AVStream *st = s->streams[idx];
+    uint8_t *buf = os->buf + os->pstart;
+    int version_major, version_minor;
+    int64_t start_num, start_den, start_granule;
+    int target_idx, start_time;
+
+    strcpy(st->codec->codec_name, "skeleton");
+    st->codec->codec_type = CODEC_TYPE_DATA;
+
+    if (os->psize < 8)
+        return -1;
+
+    if (!strncmp(buf, "fishead", 8)) {
+        if (os->psize < 64)
+            return -1;
+
+        version_major = AV_RL16(buf+8);
+        version_minor = AV_RL16(buf+10);
+
+        if (version_major != 3) {
+            av_log(s, AV_LOG_WARNING, "Unknown skeleton version %d.%d\n",
+                   version_major, version_minor);
+            return -1;
+        }
+
+        // This is the overall start time. We use it for the start time of
+        // of the skeleton stream since if left unset lavf assumes 0,
+        // which we don't want since skeleton is timeless
+        // FIXME: the real meaning of this field is "start playback at
+        // this time which can be in the middle of a packet
+        start_num = AV_RL64(buf+12);
+        start_den = AV_RL64(buf+20);
+
+        if (start_den) {
+            av_reduce(&start_time, &st->time_base.den, start_num, start_den, INT_MAX);
+            st->time_base.num = 1;
+            st->start_time = start_time;
+        }
+    } else if (!strncmp(buf, "fisbone", 8)) {
+        if (os->psize < 52)
+            return -1;
+
+        target_idx = ogg_find_stream(ogg, AV_RL32(buf+12));
+        start_granule = AV_RL64(buf+36);
+        if (target_idx >= 0 && start_granule != -1) {
+            s->streams[target_idx]->start_time = ogg_gptopts(s, target_idx, start_granule, NULL);
+        }
+    }
+
+    return 1;
+}
+
+const struct ogg_codec ff_skeleton_codec = {
+    .magic = "fishead",
+    .magicsize = 8,
+    .header = skeleton_header,
+};