Delay Compensation with Software Instruments

[Chris August]

I'm wondering if there is a setting anywhere that I am missing...

Here's the problem. I have Delay Compensation turned on. I have an INST track with let's say Omnisphere (does this with any plugin) opened up. I decide I want some tremolo on this synth I just found so I open up Sound Toys - Tremolator. The tremolo won't play in time. Turns out it does this on any sort of Instrument track in Pro Tools. Commit it to 'audio' and it works fine. Turn off Delay Compensation and it plays in time.

Basically Pro Tools doesn't use Delay Compensation on Instrument tracks. Am I missing something? I opened up Logic Pro and did a test with the exact same setup and it works fine. Obviously, we all know Logic cares about Midi way more than Pro Tools does.

Note: This is when you have a session with some plugins and whatnot going on other tracks. If you were to do this in a blank session in Pro Tools it would work fine because nothing is getting compensated yet.

Has anyone else run into this problem and found a solution?

Thanks!
Chris

[Sardi]

Sounds like the extra plugins you have are inducing delay and it’s throwing off Tremolator’s BPM sync which it’s getting from the PT session tempo.

If you do a search on the DUC there’s a few quite lengthy threads about this that go into a lot of detail.

Short answer - yes, it appears to be broken.


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[smokeydan]

A couple of years ago I was struggling with what I think is a related issue. I had a virtual instrument which was running a step sequencer within the VI, and was always out of time. But when I tried running the same VI as an insert on an Aux track, it played in time. I concluded that Instrument Tracks appear to do their delay compensation in the midi domain (delay compensation is applied before the audio stream through the inserts - whether this is actually the case I'm still not 100% sure, but running the VI on an Aux definitely worked for me in this instance, so maybe try running the instrument track into an Aux, place the tremolator on the aux and see if this works for you?

[Eric Lambert]

Yes, we often have to play with the host of the VI when delay comp begins to slide. We always start with VIs on Instrument tracks, but sometimes it takes instantiation on an Audio or Aux track for compensation to return properly.

The problem does get worse as your session grows and PT needs to compensate to larger degrees due to plugin processing time. Unfortunately, it doesn't seem to properly calculate for many things. However, if you're referring to playing live along with the track, PT can't offset MIDI in order to bring it in-time because it's unable to offset your live and unpredictable playing. It seems to me that it should recognize the phenomenon and do the proper math, but it seems to get confused.

[JingleDjango]

I was told by support that there is no automatic delay compensation for MIDI events at all.

[Eric Lambert]

Originally Posted by JingleDjango

I was told by support that there is no automatic delay compensation for MIDI events at all.

That answer will vary depending on how the question was posed. PT absolutely compensates for recorded MIDI, and typically does so quite well. But for live playing, it does not compensate because it's unable to offset all other audio in real time. It can't predict when it will receive MIDI notes. So PT does compensate in most cases, certainly during playback.

What we might be talking about here, though, is the issue with delay plugins (for instance) when playing live. Delays start late, by the amount of the buffer, and that's not altogether surprising, but what PT should be doing is repairing the added time of the delay plugin by subtracting the appropriate amount of time based on the buffer/sample-delays/etc. I often find that it does not, yet sometimes it does. There are plugins do not communicate well with the DAW, and those seem to be the most problematic in this way. PSP had a couple plugs that were plagued with ADC timing issues, and then they released an update and the issues were gone. So, at least in some cases, it's not entirely on ProTools.

But there is a way to handle delay compensation, both recorded and live. As mentioned, other DAWs do it. I've never noticed this issue in Logic.