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SuperVP crackle problem

Forumnet Legacy general discussion
#1

Dear SuperVP for MAX developers,

I am a fan of the superVP sound and it is perfect in my interactive harmonisation patch for the Electrumpet but now and then it does not link up with MAX when I use it in poly~ or dynamicdsp~ (from Alexander Harker). Syncing problems introduce crackle it seems. It is a recurring problem although I have not noticed it for over a half year until I recently updated my RME firmware and driver. Somehow I think that going back to the old driver won’t solve the problem but it is a course of action I still have to take. I do think though that I have been in luck for a while and that my luck ran out. I hope something in superVP itself can be done or that somebody has a solution…

I think it was mentioned that superVP has to be used in overdrive and with audio interrupt in MAX. When I use audio interrupt the software won’t work at all in my patch (probably because the rest of my patch is too intensive) but with overdrive on and without ‘audio interrupt’ it worked fine until this week. The problem probably arose because of the update of the RME firmware/driver, but it might also have been the ADAT syncing that we could not get right (a lot of crackle) and the reason to go for a new driver in the first place.

Does anyone have a tip that will minimise the crackling? Maybe try it with local scheduling in a poly object? Experiences?

At the moment I use it in MAX 7 running with an io vector size of 256 (A longer vector size will introduce too much latency in other parts of my patch). I use superVP within dynamicdsp~ (from the Harker objects) this allows me to run at least three voices of SuperVP before running into problems like hick-ups in my current patch.

Best, Hans.

#2

@hansleeuw : SuperVP can be safely used in parallel processing and poly~ (though I know nothing of dynamicdsp~) but you should be very careful with parameters. Normally you should NOT use a small Signal Vector Size for a simple reason: SuperVP calculates things every once in a while; which depends on the Analysis Windows size in samples and the overlap/add factor. For example, object instantiation with parameters ‘4096 4’ will lead to updates every 1024 samples. If you signal vector size is too small (let’s say 64) then SuperVP will not have enough time until the next cycle (next 64 samples) to do its computation and you’ll hear clicks. This usually happens in big patches.

To overcome this, you should increase your Signal Vector size (either globally or inside the Poly~ abstraction) which is more important in this case than io vector size. Put it for example equal to 256!

Also, I do NOT recommend using Audio Interrupt which is always technically interesting but practically impossible to achieve on concert patches! But you need Overdrive ON.

I have personally used multiple instances (up to 8) of SuperVP objects in a single patch in 96Khz and Poly~ with no problem.