From 549bc3c80ed8891ff746eeef20f9217328ae0cef Mon Sep 17 00:00:00 2001
From: Wim Taymans <wim.taymans@collabora.co.uk>
Date: Thu, 6 May 2010 10:56:21 +0200
Subject: [PATCH] oggdemux: use index to estimate bitrate

When we have an index, use it to much more accurately estimate the total stream
bitrate.
---
 ext/ogg/gstoggdemux.c  | 10 +++++++---
 ext/ogg/gstoggstream.c | 20 ++++++++++++++++++++
 ext/ogg/gstoggstream.h |  1 +
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/ext/ogg/gstoggdemux.c b/ext/ogg/gstoggdemux.c
index 74d41c0..c490bee 100644
--- a/ext/ogg/gstoggdemux.c
+++ b/ext/ogg/gstoggdemux.c
@@ -1677,11 +1677,11 @@ gst_ogg_demux_activate_chain (GstOggDemux * ogg, GstOggChain * chain,
 
   /* FIXME, should not be called with NULL */
   if (chain != NULL) {
-    gint bitrate;
+    gint bitrate, idx_bitrate;
 
     GST_DEBUG_OBJECT (ogg, "activating chain %p", chain);
 
-    bitrate = 0;
+    bitrate = idx_bitrate = 0;
 
     /* first add the pads */
     for (i = 0; i < chain->streams->len; i++) {
@@ -1690,6 +1690,9 @@ gst_ogg_demux_activate_chain (GstOggDemux * ogg, GstOggChain * chain,
 
       pad = g_array_index (chain->streams, GstOggPad *, i);
 
+      if (pad->map.idx_bitrate)
+        idx_bitrate = MAX (idx_bitrate, pad->map.idx_bitrate);
+
       bitrate += pad->map.bitrate;
 
       /* mark discont */
@@ -1714,7 +1717,8 @@ gst_ogg_demux_activate_chain (GstOggDemux * ogg, GstOggChain * chain,
       gst_element_add_pad (GST_ELEMENT (ogg), GST_PAD_CAST (pad));
       pad->added = TRUE;
     }
-    ogg->bitrate = bitrate;
+    /* prefer the index bitrate over the ones encoded in the streams */
+    ogg->bitrate = (idx_bitrate ? idx_bitrate : bitrate);
   }
 
   /* after adding the new pads, remove the old pads */
diff --git a/ext/ogg/gstoggstream.c b/ext/ogg/gstoggstream.c
index 5c0303a..a4e1891 100644
--- a/ext/ogg/gstoggstream.c
+++ b/ext/ogg/gstoggstream.c
@@ -922,6 +922,26 @@ gst_ogg_map_add_index (GstOggStream * pad, const guint8 * data, guint size)
         G_GUINT64_FORMAT, n_keypoints, isize);
   }
   pad->n_index = isize;
+  /* try to use the index to estimate the bitrate */
+  if (isize > 2) {
+    guint64 so, eo, st, et, b, t;
+
+    /* get start and end offset and timestamps */
+    so = pad->index[0].offset;
+    st = pad->index[0].timestamp;
+    eo = pad->index[isize - 1].offset;
+    et = pad->index[isize - 1].timestamp;
+
+    b = eo - so;
+    t = et - st;
+
+    GST_DEBUG ("bytes/time %" G_GUINT64_FORMAT "/%" G_GUINT64_FORMAT, b, t);
+
+    /* this is the total stream bitrate according to this index */
+    pad->idx_bitrate = gst_util_uint64_scale (8 * b, pad->kp_denom, t);
+
+    GST_DEBUG ("bitrate %" G_GUINT64_FORMAT, pad->idx_bitrate);
+  }
 
   return TRUE;
 }
diff --git a/ext/ogg/gstoggstream.h b/ext/ogg/gstoggstream.h
index f47fdce..b70b5b3 100644
--- a/ext/ogg/gstoggstream.h
+++ b/ext/ogg/gstoggstream.h
@@ -89,6 +89,7 @@ struct _GstOggStream
   guint n_index;
   GstOggIndex *index;
   guint64 kp_denom;
+  guint64 idx_bitrate;
 };
 
 
-- 
2.7.4