AudioEffectFreeverbStereo - self-resonates with (internal) noise impulse?

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dirkenstein

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With damping set to 0, I've had some very odd periodic noise impulse artefacts turning up in the output of FreeVerbStereo, even with the input at 0 volume over sustained periods.

Anyway, i spotted something which might be irrelevant but seems to cure the issue when changed:

In the last line of the for( loop in the update() function it has:

outblockR->data = sat16(outputL * 30, 0);

Should this be:
outblockR->data = sat16(outputR * 30, 0);
Instead?

Otherwise it seems to throw most of the allpass filter calculations for the right output away?
In any case, changing this cured my weird self-oscillation issue. I have no idea if it's an actual issue with the code or i've understood even less of what the Freeverb code is doing than I thought I did.
 
Found the origin of the artefacts- I was feeding FreeverbStereo two channels instead of one- that overwrote one of the internal comb filter buffers silently and introduced a periodic noise. However, the original question still stands- is the right channel output buffer being populated from the wrong variable?
 
...This leads to an interesting question from someone who knows nothing of audio (comms & measurement guy here). When one refers to "reverb", is the standard of practice to separate the channels with no cross mixing, or to allow cross mixing as might happen in a physical reverberating space?
 
...This leads to an interesting question from someone who knows nothing of audio (comms & measurement guy here). When one refers to "reverb", is the standard of practice to separate the channels with no cross mixing, or to allow cross mixing as might happen in a physical reverberating space?

You do indeed cross mix reverbs. You often also use anti-phase additions to give the reverb extra width.
 
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