From 9c04d1e13c827d53ae83e3b2f6d5e9bd6ded4445 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian@centricular.com>
Date: Tue, 2 Aug 2016 08:47:55 +0300
Subject: [PATCH] dashdemux: Collect average moof and first sync sample sizes

And always request those in the beginning so that ideally we get the moof and
the first sync sample all together with the first HTTP request.

https://bugzilla.gnome.org/show_bug.cgi?id=741104
---
 ext/dash/gstdashdemux.c | 37 +++++++++++++++++++++++++++++++++++--
 ext/dash/gstdashdemux.h |  1 +
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/ext/dash/gstdashdemux.c b/ext/dash/gstdashdemux.c
index 1e7dbd4485..8ebc05b5b4 100644
--- a/ext/dash/gstdashdemux.c
+++ b/ext/dash/gstdashdemux.c
@@ -1877,7 +1877,6 @@ gst_dash_demux_need_another_chunk (GstAdaptiveDemuxStream * stream)
   /* We're chunked downloading for ISOBMFF in KEY_UNITS mode for the actual
    * fragment until we parsed the moof and arrived at the mdat. 8192 is a
    * random guess for the moof size
-   * TODO: Calculate running average for the moof size and use that instead
    */
   if (dashstream->is_isobmff
       && (GST_ADAPTIVE_DEMUX (stream->demux)->
@@ -1887,7 +1886,16 @@ gst_dash_demux_need_another_chunk (GstAdaptiveDemuxStream * stream)
       && dashdemux->allow_trickmode_key_units) {
     if (dashstream->isobmff_parser.current_fourcc != GST_ISOFF_FOURCC_MDAT) {
       /* Need to download the moof first to know anything */
+
       stream->fragment.chunk_size = 8192;
+      /* Do we have the first fourcc already or are we in the middle */
+      if (dashstream->isobmff_parser.current_fourcc == 0) {
+        stream->fragment.chunk_size += dashstream->moof_average_size;
+        if (dashstream->first_sync_sample_always_after_moof)
+          stream->fragment.chunk_size +=
+              dashstream->first_sync_sample_average_size;
+      }
+
     } else if (dashstream->moof && dashstream->moof_sync_samples) {
       /* Have the moof, either we're done now or we want to download the
        * directly following sync sample */
@@ -1915,7 +1923,9 @@ gst_dash_demux_need_another_chunk (GstAdaptiveDemuxStream * stream)
     /* We might've decided that we can't allow key-unit only
      * trickmodes while doing chunked downloading. In that case
      * just download from here to the end now */
-    if (dashstream->moof)
+    if (dashstream->moof
+        && (GST_ADAPTIVE_DEMUX (stream->demux)->
+            segment.flags & GST_SEGMENT_FLAG_TRICKMODE_KEY_UNITS))
       stream->fragment.chunk_size = -1;
     else
       stream->fragment.chunk_size = 0;
@@ -2033,6 +2043,17 @@ gst_dash_demux_parse_isobmff (GstAdaptiveDemux * demux,
           dash_stream->isobmff_parser.current_start_offset;
       dash_stream->moof_size = size;
       dash_stream->current_sync_sample = -1;
+
+      if (dash_stream->moof_average_size) {
+        if (dash_stream->moof_average_size < size)
+          dash_stream->moof_average_size =
+              (size * 3 + dash_stream->moof_average_size) / 4;
+        else
+          dash_stream->moof_average_size =
+              (size + dash_stream->moof_average_size + 3) / 4;
+      } else {
+        dash_stream->moof_average_size = size;
+      }
     } else {
       gst_byte_reader_skip (&reader, size - header_size);
     }
@@ -2249,6 +2270,18 @@ gst_dash_demux_find_sync_samples (GstAdaptiveDemux * demux,
     GstDashStreamSyncSample *sync_sample =
         &g_array_index (dash_stream->moof_sync_samples, GstDashStreamSyncSample,
         0);
+    guint size = sync_sample->end_offset + 1 - sync_sample->start_offset;
+
+    if (dash_stream->first_sync_sample_average_size) {
+      if (dash_stream->first_sync_sample_average_size < size)
+        dash_stream->first_sync_sample_average_size =
+            (size * 3 + dash_stream->first_sync_sample_average_size) / 4;
+      else
+        dash_stream->first_sync_sample_average_size =
+            (size + dash_stream->first_sync_sample_average_size * 3) / 4;
+    } else {
+      dash_stream->first_sync_sample_average_size = size;
+    }
 
     if (dash_stream->moof_offset + dash_stream->moof_size + 8 <
         sync_sample->start_offset) {
diff --git a/ext/dash/gstdashdemux.h b/ext/dash/gstdashdemux.h
index bf02a31c26..e32b7b4a89 100644
--- a/ext/dash/gstdashdemux.h
+++ b/ext/dash/gstdashdemux.h
@@ -94,6 +94,7 @@ struct _GstDashDemuxStream
   GArray *moof_sync_samples;
   guint current_sync_sample;
 
+  guint64 moof_average_size, first_sync_sample_average_size;
   gboolean first_sync_sample_after_moof, first_sync_sample_always_after_moof;
 };