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Tremulant Randomisation Anomoly Detected

PostPosted: Fri Dec 16, 2011 11:28 am
by Don Springer
I have recented detected extraordinary but occasional drops in the frequency of tremulants. In the CODM all of the trem frequency and amplitude randomization values are 10 for all of the trems.
It would seem impossible for a 10% deviation to cause the effect I have detected, in which case the trem momentarily almost stops. I noticed that the syntax of the generated values for trem randomization in the ODF changed in Hauptwerk 4 from a long decimal string (in hauptwerk 3x), to a short notation like 4e+1, and I am wondering if either the generation of the ODF from the codm is not generating the appropriate value, or if hauptwerk is misinterpreting the odf values. Any feedback is welcome. I took the step of reducing the trem randomization value in the Organ Preferences from 100 to 10 as a temporary solution.

Re: Tremulant Randomisation Anomoly Detected

PostPosted: Fri Dec 16, 2011 1:58 pm
by mdyde
Hello Don,

Could it be that your PC's CPU is being too heavily loaded? Does Windows Task Manager show very heavy CPU loading at the times that the tremulants slow down excessively?

Hauptwerk gives priority to the audio engine over the tremulants in times of extreme CPU load, to try to avoid audio glitches (since an audio glitch would probably be more catastrophic in a live situation), but extreme CPU loads can certainly cause the tremulant model and other background models to be 'choked'.

If that doesn't solve it, can you send us your CODM organ definition, the 'full-format' organ definition generated from it, and also a diagnostic file ('File | Create a diagnostic file'), so that we can see if we can reproduce it here with your organ definition and settings. Thanks.

Re: Tremulant Randomisation Anomoly Detected

PostPosted: Fri Dec 16, 2011 2:37 pm
by Don Springer
Actually, it is conceivable that the issue is CPU load. As I mentioned, I have detected this only occasionally, and I find for example, that my antivirus application can perform its updates, and seems to impede system performance while the update process is actually running. I don't think it is necessary to review the ODF at this point as I think you have described the likely cause. In general the CPU load is nominal, but I have not yet been able to prevent windows from causing occasional spikes.

Re: Tremulant Randomisation Anomoly Detected

PostPosted: Fri Dec 16, 2011 2:53 pm
by mdyde
Thanks, Don.

Re: Tremulant Randomisation Anomoly Detected

PostPosted: Sun Dec 18, 2011 4:14 pm
by steve till
This is a very good reason to use either a dedicated computer for Hauptwerk,
not connected to the internet except when necessary for updates,
or at the very least disable or unplug the internet and other non musical
applications from running while running Hauptwerk.

Windows doesn't seem to care very much about giving real time
applications the priority levels that they need.