Re: AUTimePitch -- edge artifacts
Re: AUTimePitch -- edge artifacts
- Subject: Re: AUTimePitch -- edge artifacts
- From: Brian Whitman <email@hidden>
- Date: Tue, 29 Nov 2005 20:03:11 -0500
Hi Chris, that last message got it for me. I was not seeing that the
AU kept a state. i redid my code to not re-initialize the AU every
8192 frames and to keep the sample position updated per read and it
now works fine.
Thanks so much for your patience and help, I really appreciate it.
If future people are interested in my (still pretty buggy but at
least clean output) code, I updated it:
http://variogr.am/Sinewave_AUTimePitch.zip
thanks
Brian
On Nov 29, 2005, at 5:49 PM, Chris Rogers wrote:
AudioUnits will *always* render exactly the number of sample-frames
that you ask for.
This AudioUnit has state. It reads ahead on the input side, and
internally buffers a substantial number of samples. You don't do
anything special to get output samples 8192-12000.
You feed a continuous *uninterrupted* audio stream on the input
side, and receive a continuous *uninterrupted* stream on the output
side. There are no gaps, or re-arranging of the order
of different chunks of audio. The only subtlety here is that the
behavior is slightly different depending on if you're using the
format-converter 'aufc' or offline 'auol' version of the AudioUnit.
For any AudioUnit of type 'aufc' there will be an initial bit of
silence (zero sample-frames) corresponding to the amount of latency
which the AudioUnit reports (roughly 70 milliseconds for AUTimePitch)
before the actual valid rendered output appears. You can discard
this initial bit of silence. For the offline 'auol' version the
latency (initial silence) is absorbed internally, so you will
immediately get the
expected output sample frames.
Chris Rogers
Core Audio
Apple Computer
--
Brian Whitman. http://variogr.am/
The Echo Nest Corporation
email@hidden
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