Re: Convolution Audio Unit how to?
Re: Convolution Audio Unit how to?
- Subject: Re: Convolution Audio Unit how to?
- From: tahome izwah <email@hidden>
- Date: Tue, 22 Nov 2011 00:36:11 +0100
I'd recommend you check the literature for implementation of
overlap-add and overlap-save processing. These are common
implementations for algorithms like convolution that deal with
edge-effects.
HTH
--th
2011/11/22 Mark Heath <email@hidden>:
> Hi guys,
>
> I've spent the last week searching google for information on how to do this
> but have not found anything.
> Even searching this mailing list archive returns an error. So forgive me if
> this has been asked before.
>
> I'm trying to implement an audio unit filter that behaves similar to a
> convolution matrix filter (my background is in image processing so I may use
> the wrong terminology)
>
> To calculate the new value of the current sample I need a window of samples
> either side of current sample. (from the future and past)
> I have implemented this (using AUBaseEffect) without processing the samples
> near the edge of the supplied sample frame. However I am getting some
> strange distortion that I could only attribute to not processing these edge
> samples.
>
> So I'm looking for a correct implementation of a convolution filter.
>
> My original thought was to buffer the last frame and process the sample that
> are near the edge this way but this has 2 problems;
> 1) the first sample buffer passed into the filter must output less samples
> than passed in and then I would need a tail to process the remaining
> samples.
> 2) as the filter is only receiving 1 channel, I do not know if my stored
> sample buffer is from a different channel.
>
> Could anyone help?
>
> Thanks
> Mark
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