This is all very useful information. I'm curious to see this sort of data using babo reverb, comparing moving and stationary.  That is my favored reverb sound.  

----- Original Message ----
From: Art Hunkins 
To: csound@lists.bath.ac.uk
Sent: Sunday, June 8, 2008 4:08:50 PM
Subject: [Csnd] Re: Various Reverb CPU Usages (real time)

I ran a further test: to compare CPU usage (with 16 identical voices) for a 
global reverb vs. one reverb per instrument.

Results - CPU usage with reverbs per instrument, using otherwise the same 
setup as previously:
reverbsc: 65 (vs. 11 with global reverb)
reverb (2 units): 29 (vs. 10 with global reverb)

Conclusion: Whatever else you do, in a realtime situation, make reverb 
global!

Two baseline observations confirm this conclusion. Keeping the same 
instruments except for the reverbs (I kept locsit, locsend and denorm), 
these CPU usages were seen:
One-voice baseline: 3.5
16-voice baseline: 10

Further conclusion: In single voices, the presence of reverb has a 
significant effect on CPU usage. In multiple voices *with global reverb*, 
the increase in CPU usage is insignificant. The most telling example from my 
tests regards 16 voices with/without reverbsc:
Baseline 16-voice (no reverb): 10
16-voice global reverb (reverbsc): 11
16-voice with individual reverbs (reverbsc): 65 !!

Final observation: The fewer reverbs in individual instruments, the less the 
CPU percentage. With larger numbers of instruments, the particular reverb 
opcode you use is insignificant - as long as the reverb is global.

Art Hunkins

----- Original Message ----- 
From: "Art Hunkins" 
To: 
Sent: Sunday, June 08, 2008 2:03 PM
Subject: Various Reverb CPU Usages (real time)


>I have just run comparative CPU usage tests on the various reverb opcodes 
>in a stereo setting. The opcodes tested were: reverbsc, freeverb, reverb (2 
>units required) and nreverb (2 units as well).
>
> The test orchestra consisted of a simple (vco2) oscillator, stereo locsig, 
> locsend and denorm. Tests with a single voice had the reverb within the 
> instrument. Tests were also run with 16 identical instruments running 
> simultaneously, but with a global reverb accumulator into a separate 
> reverb instrument.
>
> In WinXP (and additional applications minimized), average single voice CPU 
> usage (percentage):
> reverbsc: 7
> freeverb: 6
> reverb (2 units): 4.5
> nreverb (2 units): 5.5
>
> with 16 voices:
> reverbsc: 11
> freeverb: 11
> reverb (2): 10
> nreverb (2): 11
>
> My conclusion: The particular reverb opcode chosen makes little to no 
> difference in any but the simplest settings. Use the best quality 
> available (which IMO is reverbsc).
>
> So, I'll be using reverbsc even for OPLC. (I like reverbsc's ability to 
> randomize reflection time; this makes the reverb sonority less 
> smooth/regular, which helps with sustained tones.)
>
> Would anyone make a different choice?
>
> Art Hunkins 



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