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Overload

Official support for: mutools.com

Moderators: muzycian, mutools

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KVRAF
 
2283 posts since 5 Jun, 2012

Postby fluffy_little_something; Wed Jan 15, 2014 6:09 am Overload

I am not sure, but I think Mulab might have some CPU usage or efficiency problems or whatever you want to call it. It seems easy to overload, so that one has to restart the engine via Panic.

It has happened to me with several plugins (it seems to be a plugin problem only, Mulab's own synth doesn't seem to cause any such problems), this is the latest example:

viewtopic.php?f=1&t=387568&p=5614878#p5614856

In Mixcraft those problems do not exist (despite using exactly the same hardware and audio driver settings), and from what the others responded, they do not exist in Reaper etc., either.
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KVRAF
 
2283 posts since 5 Jun, 2012

Postby fluffy_little_something; Wed Jan 15, 2014 8:45 am Re: Overload

Seems we have narrowed the cause down to denormals:
viewtopic.php?f=1&t=387568&p=5615046#p5615046

Seems that Mulab can't handle the amount of calculations associated with denormals. Since my CPU can handle them (in Mixcraft the CPU usage rises to "only" 15 to 20%, but no overload at all), maybe the data highway between my computer and Mulab is not broad enough, from a layman's perspective :hihi:
KVRAF
 
5281 posts since 24 Jun, 2008, from Europe
    

Postby mutools; Wed Jan 15, 2014 10:15 am Re: Overload

It's not MuLab's responsability to avoid denormals inside VST plugins. A VST plugin should avoid denormals when doing its calculations. MuLab and MUX do avoid denormals at any relevant step in the MU signal chain. The only thing i could do is check whether a VST plugin's output contains denormals and fix them, but that will costs extra CPU of course. It's much better that VST plugins do not deliver denormals to the host at all.
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KVRAF
 
2283 posts since 5 Jun, 2012

Postby fluffy_little_something; Wed Jan 15, 2014 10:28 am Re: Overload

mutools wrote:It's not MuLab's responsability to avoid denormals inside VST plugins. A VST plugin should avoid denormals when doing its calculations. MuLab and MUX do avoid denormals at any relevant step in the MU signal chain. The only thing i could do is check whether a VST plugin's output contains denormals and fix them, but that will costs extra CPU of course. It's much better that VST plugins do not deliver denormals to the host at all.


Philosophically speaking you might be correct. Then again, it seems all the other popular DAW's do eliminate denormals, even Mixcraft, which is certainly not the most advanced one out there :hihi: Plus, the CPU load necessary for that elimination is probably a whole lot less than that resulting from denormals 8)

It's a bit like with webpages. Many are sloppy and contain errors. IE is known to cope with and correct such errors better than browsers that strictly adhere to the HTML and similar rules.

Unfortunately, sloppy VST's and web pages are a fact one has to live with. I might be a bit extreme, but frankly, since I love that new Oberheim emulation a lot, this issue would be severe enough for me to switch DAW's :? I hope the developer fixes his synth...
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KVRAF
 
2283 posts since 5 Jun, 2012

Postby fluffy_little_something; Wed Jan 15, 2014 4:29 pm Re: Overload

OK, the developer has fixed his synth, no more overload in Mulab, either :)
KVRAF
 
5281 posts since 24 Jun, 2008, from Europe
    

Postby mutools; Wed Jan 15, 2014 10:08 pm Re: Overload

Thanks for posting the update fluffy, much apreciated. I've added a wishlist note about adding a denormal killer on the output of VSTs. I guess that would be enabled by default, but can be disabled via a preference.
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KVRAF
 
2283 posts since 5 Jun, 2012

Postby fluffy_little_something; Thu Jan 16, 2014 6:53 am Re: Overload

mutools wrote:Thanks for posting the update fluffy, much apreciated. I've added a wishlist note about adding a denormal killer on the output of VSTs. I guess that would be enabled by default, but can be disabled via a preference.


Yes, I am happy he fixed the denormal problem. But that plugin still behaves oddly in Mulab. As soon as I load one instance, the CPU meter goes to about 20%, and it stays there regardless if it is idle or if I play chords, jumping between 15 and 25%. It should consume hardly any CPU in idle mode in my view, which is the case in Mixcraft according to the resource monitor (didn't trust the DAWs' CPU meters, so I tried the Windows monitoring system, but it shows the same difference as the DAW meters...)

Since I am not a programmer, is that denormal problem an on-off problem or a gradual one. I.e. is the denormal problem one that can only be there or completely gone, or can it be reduced so that it is still there to a certain degree?

PS: It clearly has to do with the number of voices as if I turn the synth to mono mode, the CPU meter drops to about 4% in idle mode, and with every additional voice it increases accordingly.
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KVRAF
 
2283 posts since 5 Jun, 2012

Postby fluffy_little_something; Thu Jan 16, 2014 4:39 pm Re: Overload

I was just trying the new Diva demo, and had the same problem. Since I only tried it in Mulab in the past as well, I always thought my computer was just too weak for it.
But today I tried it in Mixcraft, just between 7 and 10% for a chord in divine mode :) That is actually just about the same level as with new Oberheim emulation I was testing before.

Tried it Mulab again, too. Same patch. Between 50 and 60% for the same chord. And as soon as I enable Diva's multicore mode (which oddly leads to a slightly higher CPU load in Mixcraft than without multicore mode), Mulab's sound engine overloads and the entire computer freezes. After about 15 secs I can finally close Mulab.

U-he is a renowned company, I don't think their expensive synth has bugs like denormals. Has anyone else tried Diva in Mulab (latest version, 32-bit)?
KVRAF
 
5281 posts since 24 Jun, 2008, from Europe
    

Postby mutools; Fri Jan 17, 2014 4:33 am Re: Overload

About denormals, please read http://en.wikipedia.org/wiki/Denormal_number

About the cpu usage: Note that when MuLab operates in multi-core mode, there are several audio threads working at the same time. If you have a quad core machine and have enabled 4 audio threads, then inserting a single synth might result in a higher than expected cpu usage value because the other 3 audio threads are taken into account too. But thing is that when inserting a 2nd synth parrallel to the first one, does not necessarily increase the cpu weight because there are still 3 threads ready to work. I hope i explained well. Bottomline is: Don't only watch the number, but check things more practically. Or do this test: Set Mixcraft to single core, and MuLab to 1 audio thread, then compare again.

About the freezing when using multi-core VSTs: Read http://www.mutools.com/info/docs/mulab/audio-setup.html

About using VSTs (eg Diva), cpu weight and denormals etc: I think you were mixing up things a bit. Hope the above info clarifies things some more.
User avatar
KVRAF
 
2283 posts since 5 Jun, 2012

Postby fluffy_little_something; Fri Jan 17, 2014 8:31 am Re: Overload

Regarding Mulab, seems it has to do with Diva's multicore support:

Mulab set to 4 cores:
3 instances/chords:
load 45:50 (Windows:Mulab meter) with Diva's mc support on
load 40:60 mc support off

Mulab set to 5 cores:
3 instances/chords:
load 60:80 (Windows:Mulab meter) with Diva's mc support on
load 45:55 mc support off

Mulab set to 6 cores:
3 instances/chords:
immediate overload with Diva's mc support on
load 55:55 (Windows:Mulab meter) mc support off



Since I can only select single core or all cores in Mixcraft, here the data for that DAW, same patch, some chords:

Mixcraft set to 1 core:
3 instances/chords:
load 30:27 (Windows:Mixcraft meter) with Diva's mc support on
load 18:14 with Diva's mc support off

(added a forth instance/chord, 37:33 with mc support on, and 20:16 with mc suppor off, however there is a lot of distortion both with and without mc support, obviously too much for 1 core :lol: )

Mixcraft set to 6 cores:
3 instances/chords:
load 33:30 (Windows:Mixcraft meter, obviously it means something different as unlike with Mulab the Mixcraft loads are always smaller than the Windows loads) with Diva's mc support on
load 21:17 with Diva's mc support off

(added a forth instance/chord, 50:45 with mc support on, and 40:35 with mc support off, however there is a lot of distortion without mc support, so it makes sense to use it with 6 cores, unlike in Mulab)
(added a fifth instance/chord, 63:59 with mc support on; looks like half a dozen or so instances/chords is close to the limit in Mixcraft; maybe one more since I switched all instances to Divine mode when I added the 4th and 5th instance; up until three instances I had only used the Great mode in both Mulab and Mixcraft; and who plays 7 3-finger chords simultaneously anyway?)

Up until 4 cores Diva's multicore support helps in Mulab, but it seems incompatible with 5 and 6 cores.
In Mixcraft Diva's mc support always leads to a higher load, but never leads to overloads.

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