Oversampling on convolution reverb

[tomekslesicki]

Hi guys! How can I implement oversampling on the convolution reverb fx? I'm getting some aliasing on 44.1 and 48 but it's gone at 88 and 96. Thanks!

[tomekslesicki]

@Christoph-Hart I really wish there was a button for that But for now, is there a walkaround?

[tomekslesicki]

I noticed there’s an oversample node in the scriptnode view but I’ve got no idea how to implement that, especially since I never used the scriptnode features and the convolution files are swapped via the interface.

[Lindon]

@tomekslesicki there was a long discussion here about Convolution reverbs and sample rates - try searching the forum.. I cant recall who it was... sorry.

[lalalandsynth]

@tomekslesicki i am very interested in this as well , i did see a discussion about sample rates changing the volume of the reverb as well, not sure if that was resolved ?

[tomekslesicki]

Yeah, I've seen every thread that contained word 'convolution' by now. It's just that there seems to be no solution. @Christoph-Hart ?

[tomekslesicki]

Ok, I think it has to do something with IPP. When I build HISE without it and then compile the plugin it seems to work fine.

[Christoph Hart]

Can you send me the IR in question? IIRC @hisefilo also had a certain impulse response that triggered some issues with the first frequency bin in the FFT.

[hisefilo]

@Christoph-Hart Choosing Ooura FFT this fixed that issue. I can remember

// oninit

 const var ConvolutionReverb1 = Synth.getEffect("Convolution Reverb1");
 
 // Set the FFT type
 // 0 = best available
 // 1 = IPP
 // 2 = Apple Accelerate
 // 3 = Ooura FFT (slower fallback, but most portable)
 ConvolutionReverb1.setAttribute(ConvolutionReverb1.FFTType, 0);

[Christoph Hart]

Ah nice, so I didn't fix the IPP version back then

[d.healey]

What about adding KISSFFT?

[lalalandsynth]

Is the convolution set to 0 " best available" as default ?

[lalalandsynth]

Verfied , have aliasing here as well....maybe !

Although not sure that is aliasing I am at 96k and that makes no difference, guess I need to try another export with the Ooura ?
I dont get that 20K spike when using the same impulse in other reverbs

[lalalandsynth]

@hisefilo Are you referring to the aliasing issue by using Ooura ?
What does slower fallback mean and would you recommend just using the Ooura even though IPP has been recommended up to now ?

TESTING:

If i change the FFT type from 0, I lose the reverb and get some sort of room type doubling sound
Setting it back to zero does not help.

Setting it to 3 seems to get rid of most of the "Aliasing" , but I also lose the reverb so....hehe

MORE TESTING

Sine wave through Reaper Reaverb using my Impulse.

Same Sine , same impulse through my plugin.

I dont think its impulse specific as all my 90 impulses look like that .

Vocals through Reaverb.

Vocals through my plug, same impulse.

[hisefilo]

@lalalandsynth no aliasing on 0oura but IPP

Don't know details about the comments on the code I posted. It's old @Christoph-Hart magic!

[lalalandsynth]

@hisefilo ok, but it does not seem to work for me , lose the reverb sound if I change the FFT mode.

I am going to test some more impulses , but I think its pretty clear that there is a problem.
My reverb plugin is just about ready

[lalalandsynth]

@Christoph-Hart

Any chance to get a fix for this?
Was planning an impulse reverb as my first release.

[hisefilo]

@lalalandsynth an oversampled convolution node on scriptnode?

[lalalandsynth]

@hisefilo Oh, that is possible , does it behave in a similar way in terms of loading impulses etc or do I have to do everything over ?

Will check it out.

[lalalandsynth]

@lalalandsynth Quick test and that seems to work to get rid of the aliasing!
8x oversampling, maybe even 2 x would be enough , now I just need to find out if I can replace those impulses on the fly or if the scriptnode impulse is meant to just sit there as an static impulse ?

I suspect i cannot even get a reference for the Convolution Module in the scriptnode, is there some way to script the switching of impulses in scriptnode ?

I can export the Convolution module as ccp and make the changing of impulses public i.e create a meta node but unsure of how to include the oversampling in that ?

Man..if there was only a knob for the index.....sigh .