gst-libs/gst/audio/audioclock.c (gst_audio_clock_set_active)

Original commit message from CVS:
2004-11-27  Martin Soto  <martinsoto@users.sourceforge.net>

* gst-libs/gst/audio/audioclock.c (gst_audio_clock_set_active)
(gst_audio_clock_get_internal_time):
Fix active <-> inactive transitions: ensure time value always
grows and avoid abrupt value changes.

2 files changed, 26 insertions, 9 deletions

diff --git a/ChangeLog b/ChangeLog
index 35b9dbb3c..fb2cc6f3b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2004-11-27  Martin Soto  <martinsoto@users.sourceforge.net>
+
+	* gst-libs/gst/audio/audioclock.c (gst_audio_clock_set_active)
+	(gst_audio_clock_get_internal_time):
+	Fix active <-> inactive transitions: ensure time value always
+	grows and avoid abrupt value changes.
+
 2004-11-27  Arwed v. Merkatz <v.merkatz@gmx.net>
 	* configure.ac:
 	* gst/tta/Makefile.am:
diff --git a/gst-libs/gst/audio/audioclock.c b/gst-libs/gst/audio/audioclock.c
index 75c4c1c56..65d2694f2 100644
--- a/gst-libs/gst/audio/audioclock.c
+++ b/gst-libs/gst/audio/audioclock.c
@@ -109,22 +109,32 @@ gst_audio_clock_new (gchar * name, GstAudioClockGetTimeFunc func,
 void
 gst_audio_clock_set_active (GstAudioClock * aclock, gboolean active)
 {
-  GstClockTime time;
+  GstClockTime audio_time, system_time;
   GstClock *clock;
+  GTimeVal timeval;
 
   g_return_if_fail (GST_IS_AUDIO_CLOCK (aclock));
   clock = GST_CLOCK (aclock);
 
-  time = gst_clock_get_event_time (clock);
+  if (active == aclock->active) {
+    /* Nothing to do. */
+    return;
+  }
 
-  if (active) {
-    aclock->adjust = time - aclock->func (clock, aclock->user_data);
-  } else {
-    GTimeVal timeval;
+  audio_time = aclock->func (clock, aclock->user_data);
 
-    g_get_current_time (&timeval);
+  g_get_current_time (&timeval);
+  system_time = GST_TIMEVAL_TO_TIME (timeval);
 
-    aclock->adjust = GST_TIMEVAL_TO_TIME (timeval) - time;
+  /* Set the new adjust value in such a way that there's no abrupt
+     discontinuity, i.e. if gst_audio_clock_get_internal_time is
+     invoked right before and right after (de)activating the clock,
+     the values returned will be close to each other, and the second
+     value will be greater than or equal than the first. */
+  if (active) {
+    aclock->adjust = aclock->adjust + system_time - audio_time;
+  } else {
+    aclock->adjust = aclock->adjust + audio_time - system_time;
   }
 
   aclock->active = active;
@@ -141,7 +151,7 @@ gst_audio_clock_get_internal_time (GstClock * clock)
     GTimeVal timeval;
 
     g_get_current_time (&timeval);
-    return GST_TIMEVAL_TO_TIME (timeval);
+    return GST_TIMEVAL_TO_TIME (timeval) + aclock->adjust;
   }
 }