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Thanks for these numbers, Art. They confirm my suspicions that babo isn't very efficient.
----- Original Message ----
From: Art Hunkins
To: csound@lists.bath.ac.uk
Sent: Monday, June 9, 2008 12:01:34 AM
Subject: [Csnd] Re: Re: Re: Various Reverb CPU Usages (real time)
Hi, Mark -
I ran comparable tests for babo and came up with the following results. I
only tested *stationary* data (i.e., static variables), as this was what I
used on all other tests. Since I was testing with stereo locsig, babo
required two units. I took the left output of one (locsend's left output) to
left audio out, and the right output of the other (locsend's right output)
to right audio out, FWIW.
babo (2 units required):
Average single-voice CPU: 27%
Average 16-voice CPU (global reverb): 33%
Average 16-voice CPU (individual reverbs): 58%, and with somewhat wider
variance (here 50-70%) than other tests
I've no idea why the first two figures/results above are so far out of line
with other reverbs tested - especially why the single voice CPU usage is so
high. (I've double-checcked this.)
Conclusion? Babo, at least for stereo realtime, is far and away the least
efficient reverb, even under the most ideal conditions. The only place where
it compares with others is with multiple individual reverbs (the worst case
scenario) - and here it only compares with reverbsc.
Art Hunkins
----- Original Message -----
From: "mark jamerson"
To:
Sent: Sunday, June 08, 2008 6:46 PM
Subject: [Csnd] Re: Re: Various Reverb CPU Usages (real time)
> 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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