Re: Writing an audio transform filter



On Tue, 26 Sep 2006 07:12:02 -0700, cnickl wrote:

I want to do a tempo/pitch transform on an audio stream. I know (sort of)
what to do. Iʼm just not sure what to use to do this. Should I write a
Transform filter, a DMO or would using the SampleGrabber be sufficient?

It depends on whether the sample size is anticipated to change.

For example, the simplest of tempo changes is to remove a percentage of the
PCM samples from the audio data sample. This results in the sample data
passed out being a different size than what came in. So in this case by
definition you can't use the SampleGrabber. A DMO is possible in theory,
but I had a hard time getting DMO's to work correctly with varying output
sample size. DMO's are used everywhere in that scenario so I know it's
possible. Personally though, unless you had plans to use it places where
only DMO's are supported I would go with a Transform filter.

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