Noise or artefact when ramping gain to 0.0 on stereo mixer
Noise or artefact when ramping gain to 0.0 on stereo mixer
- Subject: Noise or artefact when ramping gain to 0.0 on stereo mixer
- From: Jean-Francois Roy <email@hidden>
- Date: Mon, 3 Apr 2006 22:03:37 -0400
I am currently working on a very simple audio engine that lets me
play samples from generic "audio source" objects. A source must be
attached to a "renderer object", which is just a fancy wrapper around
a stereo mixer AU connected to the default output AU.
One feature offered by renderers is source gain and pan ramping, by
scheduling appropriate parameter ramp events on the mixer AU (input
scope, on the appropriate input bus).
I've been doing some tests of that functionality this afternoon, and
discovered that when the gain is ramped from whatever to 0.0f, I can
hear a distinctive pop / click / noise / artifact when the ramp
reaches 0.0f. This has me somewhat puzzled. Either I'm doing
something wrong or there is a problem in the stereo mixer. However,
it could also be a known limitation and I should instead ramp to 0.0f
+ epsilon. I haven't tested as much, but I believe the same symptom
appears when I ramp the pan to 0.0f. There is no problem when ramping
to 1.0f that I can discern.
I can post source code if it can help. I'm just looking for advice
right now.
Thanks!
Jean-Francois Roy
--
Co-Founder of MacStorm
/dev/klog. You better pipe that through your mind.
http://www.devklog.net
http://www.macstorm.org
email@hidden
http://www.macstorm.org/bahamut/Jean-Francois.gpgkey
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