[FFmpeg-devel] [PATCH] jack: fix timefilter feedback factor computation.

[Nicolas George]

Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
---


This was not tested beyond build on Debian stable, but the PDF file in the
comments of timefilter.c say b=\sqrt{2}\omega rathar than b=\sqrt{2\omega},
and experimentally (on software-generated noised signal), it makes a huge
difference on the efficiency of the filter.

Regards,

-- 
  Nicolas George



 libavdevice/jack_audio.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/libavdevice/jack_audio.c b/libavdevice/jack_audio.c
index d0a09ee..6f5138a 100644
--- a/libavdevice/jack_audio.c
+++ b/libavdevice/jack_audio.c
@@ -183,7 +183,7 @@ static int start_jack(AVFormatContext *context)
     /* Create time filter */
     period            = (double) self->buffer_size / self->sample_rate;
     o                 = 2 * M_PI * 1.5 * period; /// bandwidth: 1.5Hz
-    self->timefilter  = ff_timefilter_new (1.0 / self->sample_rate, sqrt(2 * o), o * o);
+    self->timefilter  = ff_timefilter_new (1.0 / self->sample_rate, M_SQRT2 * o, o * o);
 
     /* Create FIFO buffers */
     self->filled_pkts = av_fifo_alloc(FIFO_PACKETS_NUM * sizeof(AVPacket));
-- 
1.7.2.5