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List:       linux-audio-dev
Subject:    [LAD] Re: stereospread.lv2 - Stereo spreading plugin (conjugate random phase all-pass filter pair)
From:       Florian Paul Schmidt <mista.tapas () gmx ! net>
Date:       2023-05-16 8:41:25
Message-ID: f26d8ecf-0111-5dd2-f1d8-20bb7eb85fcf () gmx ! net
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Hi Fons!

On 11/16/2022 2:14 PM, Fons Adriaensen wrote:
> On Wed, Nov 16, 2022 at 12:51:44PM +0100, Florian Paul Schmidt wrote:
>
> 2. If you measure this, you will also note amplitude differences between
>     L and R outputs. This is to be expected. Even if the two filters have
>     exact unity gain (and just a phase shift) at each frequency corresponding
>     to an FFT bin, the resulting filter will not be all-pass.

Thanks for this comment. It took me a while to grok what you meant. It's
not all-pass because we're in the DFT-World where the FFT-bins are just
_samples_ of the real spectrum. So between these samples non-unity gain
shows up. One way of measuring this would be to use a much longer FFT to
increase the frequency resolution, right?

Kind regards,
FPS


--
https://dfdx.eu
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