liveadder: round when calculation length from duration

liveadder sometimes calculates the offsets incorrectly before adding. The
resulting errors can easily be heard when mixing silence with a sine.
I'm not sure what the exact conditions are to trigger this, but it definitively
happens when the buffers of two streams have a different duration and buffer
length and duration don't match exactly for one stream because of rounding
errors (e.g.  duration=0:00:00.021333333)

I have to admit, I got lost in the math somewhere but it seems that not
rounding in gst_live_adder_length_from_duration() causes 1 sample overlaps in
consecutive buffers from the same stream.
When using gst_util_uint64_scale_int_round() instead of just truncating the
sine sound correctly again.

https://bugzilla.gnome.org/show_bug.cgi?id=708345

diff --git a/gst/liveadder/liveadder.c b/gst/liveadder/liveadder.c
index 0500e4bbd813596853a517727d6d8a1a6c022a60..f41de3fe19d114546b66934641cdd74fdf07ef0c 100644 (file)
--- a/gst/liveadder/liveadder.c
+++ b/gst/liveadder/liveadder.c
@@ -918,7 +918,8 @@ gst_live_adder_length_from_duration (GstLiveAdder * adder,
     GstClockTime duration)
 {
   guint64 ret = GST_AUDIO_INFO_BPF (&adder->info) *
-      (duration * GST_AUDIO_INFO_RATE (&adder->info) / GST_SECOND);
+      gst_util_uint64_scale_int_round (duration,
+      GST_AUDIO_INFO_RATE (&adder->info), GST_SECOND);
 
   return (guint) ret;
 }