[PD] Making a Realtime Convolution External

Archontis Politis deadflagblue at gmail.com
Wed Apr 6 18:42:25 CEST 2011


Hi Seth,

In terms of feature requests, since you are doing all the work already, 
it would be nice to have 1x4 mode, meaning one input ->4 convolutions->4 
outputs. That would be great for ambisonic (b-format) 4-channel room 
impulse responses.

Regards,
Archontis

On 4/5/11 3:54 AM, Seth Nickell wrote:
> I'm planning to release our realtime convolution engine (extracted
> from http://meatscience.net/pages/convolution-reverb) as a GPLed Pd
> external.
>
> It currently accepts 4-channel ('true stereo'), two channel or mono
> impulse responses, with stereo or mono output. Performance is
> excellent if you have SSE3 and has a fallback in case you don't, and
> it aims for accuracy (basically that means multi-stage scaling to keep
> floats within healthy sizes).
>
> 1) I'd love to swipe the convolve~ external name, currently installed
> by mjlib as part of pd-extended. convolve~ from mjlib appears to be a
> copy of pin~ ? so I think it could be taken? Maybe I mis-read the
> code. I've cc'ed mark who can probably clarify.
>
> 2) Anyone have requests for features/api? Its currently simplistic:
>     - takes a "read FILENAME" message, loads the file, does a test
> convolution against pink noise to normalize the gain to something sane
>     - caches the last N impulse responses, as the test convolution
> takes a little time
>     - allows setting the cache size with a "cachesize N" message
>     - disable normalization with "normalize 0" or "normalize 1"
>
>    Features I'm considering (let me know if they sound useful):
>      - load from an array instead of from disk (no gain normalization?)
>      - It wouldn't be hard to enable MxN convolution if that floats
> somebody's boat.
>
> 3) I can compile/test on Mac&  Linux, anyone up for helping me with Windows?
>
> 4) Would this be of interest for Pd-extended?
>
> 5) I'd love to build a granular convolution engine.... takes two
> real-time signals, and extracts grains from one to convolve against
> the other. Anyone have ideas about this?
>
> thanks all,
>
> -Seth
>
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