basesink: Fix QoS/lateness checking if subclass implements prepare/prepare_list vfuncs

In basesink functions gst_base_sink_chain_unlocked(), below code is used to
checking if buffer is late before doing prepare call to save some effort:
    if (syncable && do_sync)
      late =
          gst_base_sink_is_too_late (basesink, obj, rstart, rstop,
          GST_CLOCK_EARLY, 0, FALSE);

    if (G_UNLIKELY (late))
      goto dropped;

But this code has problem, it should calculate jitter based on current media
clock, rather than just passing 0. I found it will drop all the frames when
rewind in slow speed, such as -2X.

https://bugzilla.gnome.org/show_bug.cgi?id=749258

diff --git a/libs/gst/base/gstbasesink.c b/libs/gst/base/gstbasesink.c
index a505695..5fb2d6a 100644 (file)
--- a/libs/gst/base/gstbasesink.c
+++ b/libs/gst/base/gstbasesink.c
@@ -3369,10 +3369,28 @@ gst_base_sink_chain_unlocked (GstBaseSink * basesink, GstPad * pad,
     if (G_UNLIKELY (stepped))
       goto dropped;
 
-    if (syncable && do_sync)
-      late =
-          gst_base_sink_is_too_late (basesink, obj, rstart, rstop,
-          GST_CLOCK_EARLY, 0, FALSE);
+    if (syncable && do_sync) {
+      GstClock *clock;
+
+      GST_OBJECT_LOCK (basesink);
+      clock = GST_ELEMENT_CLOCK (basesink);
+      if (clock && GST_STATE (basesink) == GST_STATE_PLAYING) {
+        GstClockTime base_time;
+        GstClockTime stime;
+        GstClockTime now;
+
+        base_time = GST_ELEMENT_CAST (basesink)->base_time;
+        stime = base_time + gst_base_sink_adjust_time (basesink, rstart);
+        now = gst_clock_get_time (clock);
+        GST_OBJECT_UNLOCK (basesink);
+
+        late =
+            gst_base_sink_is_too_late (basesink, obj, rstart, rstop,
+            GST_CLOCK_EARLY, GST_CLOCK_DIFF (stime, now), FALSE);
+      } else {
+        GST_OBJECT_UNLOCK (basesink);
+      }
+    }
 
     if (G_UNLIKELY (late))
       goto dropped;