Instability between Forte2 and SIR2

Post here if you encounter problems using a plugin in forte

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Volker Grosch
Posts: 195
Joined: Sat May 26, 2007 11:29 am
Location: Germany

Instability between Forte2 and SIR2

Postby Volker Grosch » Sun Dec 27, 2009 6:33 pm

Hi,
I have some difficulties using the convolver "SIR2" (http://www.knufinke.de/sir/sir2.html). This reverberator has the advantage, that it is able to work with zero latency and needs less cpu resources than other similar plugs so it would be a good solution for me to use it in combiation with forte for live purpose.
Now the problem: using this plug in forte leads to strange behavior of the level meters on bus channels: without playing a note all busses (even those which don`t have a SIR plug implemented) show strong periodic level bursts. These bursts don`t show up in the level meters of my soundcard (RME HDSP Multiface). If I play a sound it is interupted / distorted in correlation to the bursts on the busses. I did several tests and I can say:
1) This effect is reproduceable under Win7 RC 32, 64 and Vista Home Premium 64 (2 different PC platforms)
2) The SIR plugin neither shows this behavior when used in Cubase 5 32 & 64 Bit nor in KORE2
3) Forte doesn`t show any instabilties without using the SIR plugin (beside an issue I discussed with Dirk in another thread in this forum which I think doesn`t concern this effect ==> poof effect when calling up plugins)
4) I never had any error messages concerning forte or a plugin error, so I was not able to send a report or something like that
5) As test I deinstalled the latest version of forte (Win7 32Bit) and installed an older version (2.0.116.2076) with the same result
6) As SIR2 is not freeware I first downloaded the demo and during the test I didn`t observer this issue. The effect occoured first time after I licensed the version of SIR. Btw: it was not necessary to reinstall the software for this. (Of course it could be that the testperiod was not as intensiv as it would have been necessary but please believe me: I ran more than one Stress Rack (duration 1 hour each) with a complex Rack without problems before I bought SIR2)
At this point I don`t know what I else could do to find out the reason for this problem. As I definitely don`t want to blame any of both softwares for this problem (each shows absolutely no problem without the other) I would kindly ask if there is a possibilty to do deeper testing on this issue. Of course I will also ask the developer of SIR for help.
Thanks in advance, Volker
hosts: Forte 4, AuxBusFaders, Cubase 8, Cantabile 2, Live9, jBridge
VSTis: u-he, Spectrasonics, NI, GSi, Synthogy, East West, TAL, Adam Szabo, Steinberg...
VSTs: u-he, Voxengo, Fabfilter, Lexicon, TB, PSP, NI, UVI, Waves,...

Dirk Offringa
Posts: 3508
Joined: Sat Mar 06, 2004 3:44 am
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Re: Instability between Forte2 and SIR2

Postby Dirk Offringa » Mon Dec 28, 2009 6:58 am

Hi

This is a problem that also concerns Voxengo's Pristine Space, that's the convolution processor I use live. The VU meter bursts in forte are audio dropout indicators. Using convolution processors with very low latencies is a bit a borderline exercise. I can run several instances of Pristine Space, but only one cof those can be in "high quality" mode, the others must be in "low quality" mode, otherwise I experience the same issue.

Don't mix up "zero latency" and "no latency at all". The plugin must achieve processing the block of data the host provides it, in less time than the "time-value" of that blocksize: if the host passes a 128 samples wide blocksize, at 44.1k/sec the plugin disposes of 2,9 ms to process it otherwise the block is not completed in time and you get a dropout. "Zero Latency" means that the plugin does NOT add additional latency. Some plugins DO add additional latency (FIR, some compressors....) because they need an internal buffer that exceeds the blocksize, which they report to the host when the plugin is initialized, in which case the host is supposed to compensate for that. That is obviously not relevant in forte, forte being a live host and does not record anything, nor does it render off-line. So it doesn't do any latency compensation. Only sequencers need that, to keep tracks in sample-accurate sync.

Bottom-line: if SIR gives dropouts, look if there's a "low quality" mode; otherwise increase your buffersetting in forte. If you used 64 samples, then use 128 instead. Or, in the worst case, get a more efficient convolution engine.

Dirk
Life would be much easier if I had the source code.

Volker Grosch
Posts: 195
Joined: Sat May 26, 2007 11:29 am
Location: Germany

Re: Instability between Forte2 and SIR2

Postby Volker Grosch » Mon Dec 28, 2009 1:30 pm

Hi Dirk,

thanks for your reply. The difference between "No" and "Zero" Latenxy is clear so far. Nevertheless Zero Latency is good enough for Live Operation.
Concerning the "borderline operation": I understand that operation with low latencies is critical. On the other hand I see that I´m able to drive 8 instances of SIR2 in highest quality and Zero Latency Operation at a buffer sice of 64 in Cubase without any problem wheras I observe instabilites in Forte beginning with the 2nd instance of SIR and a buffer of 256. I tried different tweakings meanwhile (lower quality and switching off Zero Latency, increasing the buffer size of my audio card to 1024). In no case I got operation without these bursts. In the task manager I can also see that the CPU load of forte increases during these burst.

O.k. meanwhile I also got a resonse from the developer of SIR2. He promised to have a look on this item. If there are any useful news I will report them here of course.

regards, Volker
hosts: Forte 4, AuxBusFaders, Cubase 8, Cantabile 2, Live9, jBridge
VSTis: u-he, Spectrasonics, NI, GSi, Synthogy, East West, TAL, Adam Szabo, Steinberg...
VSTs: u-he, Voxengo, Fabfilter, Lexicon, TB, PSP, NI, UVI, Waves,...

Dirk Offringa
Posts: 3508
Joined: Sat Mar 06, 2004 3:44 am
Location: Sainte Anastasie, France
Contact:

Re: Instability between Forte2 and SIR2

Postby Dirk Offringa » Mon Dec 28, 2009 4:09 pm

That's interesting, and I hope Mike will catch this conversation because I also would like to get more Pristine Space instances running, and maybe we have a common bug here.
I had rung a bell a couple of times over the years in the beta forum about this issue, but being the only one who complained, this was not put on the high priority list.

Indeed, the difference with Cubase's performance is impressive. This needs to be sorted out.

Dirk
Life would be much easier if I had the source code.

MikeG
Posts: 3936
Joined: Tue Nov 19, 2002 11:56 am
Location: Houston, TX, USA
Contact:

Re: Instability between Forte2 and SIR2

Postby MikeG » Tue Dec 29, 2009 3:46 pm

I had previously investigated this. I would prefer you guys gang up on the plugin vendor and I'll be happy to supply NFR licenses to them. I need an external source to tell me what's wrong here.

Mike
----------------
Mike (brainspawn)
www.brainspawn.com/support

PLEASE NOTE that the forum is not monitored as frequently as the support site above. This forum is intended primarily as a way for users to ask other users questions about the use of Forte.

Volker Grosch
Posts: 195
Joined: Sat May 26, 2007 11:29 am
Location: Germany

Re: Instability between Forte2 and SIR2

Postby Volker Grosch » Tue Dec 29, 2009 5:39 pm

Hi Mike,

thanks for your reply and submitting an offer for a NFR license. I will forward this to christan knufinke (developer of SIR2).

regards, Volker
hosts: Forte 4, AuxBusFaders, Cubase 8, Cantabile 2, Live9, jBridge
VSTis: u-he, Spectrasonics, NI, GSi, Synthogy, East West, TAL, Adam Szabo, Steinberg...
VSTs: u-he, Voxengo, Fabfilter, Lexicon, TB, PSP, NI, UVI, Waves,...


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