Re: Noise or artefact when ramping gain to 0.0 on stereo mixer
Re: Noise or artefact when ramping gain to 0.0 on stereo mixer
- Subject: Re: Noise or artefact when ramping gain to 0.0 on stereo mixer
- From: William Stewart <email@hidden>
- Date: Tue, 4 Apr 2006 12:56:34 -0700
Jean-Francois
It would be really helpful if you could file a bug report - http://
bugreporter.apple.com with your code attached so we can reproduce the
problem..
Thanks
Bill
On 03/04/2006, at 7:03 PM, Jean-Francois Roy wrote:
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
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