qtmux: Correctly calculate the elst media start

The media start has nothing to do with the shift we have applied
but with the value of the first PTS. This is defined as:

  Dt(0) = 0
  Ct(0) = Dt(0) + CTTS(0)

So the media start is always the first CTTS.

https://bugzilla.gnome.org/show_bug.cgi?id=751361

diff --git a/gst/isomp4/gstqtmux.c b/gst/isomp4/gstqtmux.c
index 2ee662f..c43d612 100644 (file)
--- a/gst/isomp4/gstqtmux.c
+++ b/gst/isomp4/gstqtmux.c
@@ -495,6 +495,7 @@ gst_qt_mux_pad_reset (GstQTPad * qtpad)
   qtpad->last_dts = 0;
   qtpad->dts_adjustment = GST_CLOCK_TIME_NONE;
   qtpad->first_ts = GST_CLOCK_TIME_NONE;
+  qtpad->first_dts = GST_CLOCK_TIME_NONE;
   qtpad->prepare_buf_func = NULL;
   qtpad->create_empty_buffer = NULL;
   qtpad->avg_bitrate = 0;
@@ -2476,10 +2477,14 @@ gst_qt_mux_update_edit_lists (GstQTMux * qtmux)
       }
 
       if (has_gap || has_shift) {
-        guint32 shift = gst_util_uint64_scale_round (qtpad->dts_adjustment,
+        GstClockTime ctts;
+        guint32 media_start;
+
+        ctts = qtpad->first_ts - qtpad->first_dts;
+        media_start = gst_util_uint64_scale_round (ctts,
             atom_trak_get_timescale (qtpad->trak), GST_SECOND);
 
-        atom_trak_set_elst_entry (qtpad->trak, 1, duration, shift,
+        atom_trak_set_elst_entry (qtpad->trak, 1, duration, media_start,
             (guint32) (1 * 65536.0));
       }
 
@@ -3046,9 +3051,9 @@ gst_qt_mux_add_buffer (GstQTMux * qtmux, GstQTPad * pad, GstBuffer * buf)
     }
 
     if (GST_BUFFER_DTS_IS_VALID (last_buf)) {
-      pad->last_dts = GST_BUFFER_DTS (last_buf);
+      pad->first_dts = pad->last_dts = GST_BUFFER_DTS (last_buf);
     } else if (GST_BUFFER_PTS_IS_VALID (last_buf)) {
-      pad->last_dts = GST_BUFFER_PTS (last_buf);
+      pad->first_dts = pad->last_dts = GST_BUFFER_PTS (last_buf);
     }
 
     if (GST_CLOCK_TIME_IS_VALID (pad->first_ts)) {
@@ -3056,7 +3061,7 @@ gst_qt_mux_add_buffer (GstQTMux * qtmux, GstQTPad * pad, GstBuffer * buf)
     } else {
       GST_WARNING_OBJECT (qtmux, "First buffer for pad %s has no timestamp, "
           "using 0 as first timestamp", GST_PAD_NAME (pad->collect.pad));
-      pad->first_ts = 0;
+      pad->first_ts = pad->first_dts = 0;
     }
     GST_DEBUG_OBJECT (qtmux, "Stored first timestamp for pad %s %"
         GST_TIME_FORMAT, GST_PAD_NAME (pad->collect.pad),

diff --git a/gst/isomp4/gstqtmux.h b/gst/isomp4/gstqtmux.h
index bf93179..81a23fa 100644 (file)
--- a/gst/isomp4/gstqtmux.h
+++ b/gst/isomp4/gstqtmux.h
@@ -115,6 +115,8 @@ struct _GstQTPad
   /* store the first timestamp for comparing with other streams and
    * know if there are late streams */
   GstClockTime first_ts;
+  GstClockTime first_dts;
+
   guint buf_head;
   guint buf_tail;