From 5388d6e6a25c9ce8a0d8fde18dcc0d3a12b6f059 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alicia=20Boya=20Garc=C3=ADa?= <aboya@igalia.com>
Date: Thu, 24 May 2018 12:58:00 +0200
Subject: [PATCH] qtdemux: fix computation of first_duration for fragmented
 files in push mode

Since ca068865c391e87932b1268d0c675be233dd2ffe the duration of the first
frame is not used for estimating the frame rate.

For this purpose, stream->first_duration was initialized with the
duration of the first frame. In fragmented files, this was previously
done by peeking the first moof, but that can only be done in pull mode.

Fortunately, we don't really need to do that, at least with the current
design: When we are estimating the frame rate we already have the
sample table, regardless of the scheduling mode and whether the file is
fragmented or not, so we can obtain first_duration there much more
reliably.

This fixes frame rate estimation for fragmented files in push mode.

https://bugzilla.gnome.org/show_bug.cgi?id=796384
---
 gst/isomp4/qtdemux.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/gst/isomp4/qtdemux.c b/gst/isomp4/qtdemux.c
index 0ac7ff83f4..37ed2fa4f9 100644
--- a/gst/isomp4/qtdemux.c
+++ b/gst/isomp4/qtdemux.c
@@ -310,8 +310,6 @@ struct _QtDemuxStream
   guint32 n_samples;
   QtDemuxSample *samples;
   gboolean all_keyframe;        /* TRUE when all samples are keyframes (no stss) */
-  guint32 first_duration;       /* duration in timescale of first sample, used for figuring out
-                                   the framerate */
   guint32 n_samples_moof;       /* sample count in a moof */
   guint64 duration_moof;        /* duration in timescale of a moof, used for figure out
                                  * the framerate of fragmented format stream */
@@ -8201,8 +8199,12 @@ gst_qtdemux_configure_stream (GstQTDemux * qtdemux, QtDemuxStream * stream)
     /* fps is calculated base on the duration of the average framerate since
      * qt does not have a fixed framerate. */
     gboolean fps_available = TRUE;
+    guint32 first_duration = 0;
 
-    if ((stream->n_samples == 1 && stream->first_duration == 0)
+    if (stream->n_samples > 0)
+      first_duration = stream->samples[0].duration;
+
+    if ((stream->n_samples == 1 && first_duration == 0)
         || (qtdemux->fragmented && stream->n_samples_moof == 1)) {
       /* still frame */
       CUR_STREAM (stream)->fps_n = 0;
@@ -8232,14 +8234,14 @@ gst_qtdemux_configure_stream (GstQTDemux * qtdemux, QtDemuxStream * stream)
         /* stream->duration is guint64, timescale, n_samples are guint32 */
         avg_duration =
             gst_util_uint64_scale_round (duration -
-            stream->first_duration, GST_SECOND,
+            first_duration, GST_SECOND,
             (guint64) (stream->timescale) * (n_samples - 1));
 
         GST_LOG_OBJECT (qtdemux,
             "Calculating avg sample duration based on stream (or moof) duration %"
             G_GUINT64_FORMAT
             " minus first sample %u, leaving %d samples gives %"
-            GST_TIME_FORMAT, duration, stream->first_duration,
+            GST_TIME_FORMAT, duration, first_duration,
             n_samples - 1, GST_TIME_ARGS (avg_duration));
 
         gst_video_guess_framerate (avg_duration, &CUR_STREAM (stream)->fps_n,
@@ -12264,11 +12266,6 @@ qtdemux_prepare_streams (GstQTDemux * qtdemux)
         break;
       ++sample_num;
     }
-    if (stream->n_samples > 0 && stream->stbl_index >= 0) {
-      stream->first_duration = stream->samples[0].duration;
-      GST_LOG_OBJECT (qtdemux, "track-id %u first duration %u",
-          stream->track_id, stream->first_duration);
-    }
   }
 
   return ret;