Re: Does the Varispeed Unit support multi channels in phase
Re: Does the Varispeed Unit support multi channels in phase
- Subject: Re: Does the Varispeed Unit support multi channels in phase
- From: Chris Rogers <email@hidden>
- Date: Mon, 11 Oct 2004 12:14:51 -0700
Mark,
Yes, the AU Varispeed unit will process multiple channels with all
the channels in phase with each
other. Because it always processes according to the exact rate
given to it, if there are very sudden
and drastic changes to the rate in between render callbacks, clicks
or glitches could be audible.
In order to get the type of smooth operation you're looking for, I'd
recommend two things:
1. Render with a fairly small buffer size (say 64 to 512) the
smaller the better.
2. Use a very simple smoothing filter on the rate parameter, to
avoid any extreme changes
in the rate parameter from one render cycle to the next. A
simple exponential approach
filter should work just fine. You can play with the time
constant to get the best results
(time constant too slow may make the response to rate changes seem slugger;
time constant too fast may not eliminate glitches sufficiently
with extremely fast rate changes)
Chris Rogers
Core Audio
Apple Computer
Folks.
Before I embark on a complex function, I wanted to see if anyone
knew if the AU Varispeed unit supports multiple channels in phase.
I want to use it as the basis of a multichannel scrub system, where
a wheel will be used to control the speed of playback of audio from
disk. The audio is potentially coming from lots of mono files, and I
am expecting the varispeed unit to call me for data more or less
quickly depending on the rate I specify for the in to out ratio. I
wil have to do some fancy work to support forwards backwards scrub
operation.
Also, do you know if changes to the ratio will cause any clicking or
audio disruption. Since we are likely to be changing the rate quite
alot, this is another important question.
Any advice on the Varispeed unit would be appreciated.
Thanks
MarK Gilbert.
--
email@hidden
Tel: +44 208 340 5677
fax: +44 870 055 7790
http://www.gallery.co.uk
New Product ! - Zen MetaCorder
Location Sound Field Recorder
http://www.metacorder.info
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden