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-   -   MIDI notes out of sync caused by Delay Compensation? (https://duc.avid.com/showthread.php?t=409342)

Starcrash 04-05-2020 08:05 PM

MIDI notes out of sync caused by Delay Compensation or something else?
 
If I have Delay Compensation engaged while recording a MIDI performance, the resultant MIDI notes are early (very early!) relative to the grid. If I turn off DC it's normal. Is there some way around this?


I'm on PT Ultimate 2020.3.0 but I feel like this has always been an issue in PT. What I always end up doing is tap the keyboard as precisely as I can to the click and then measure the offset on the timeline and nudge the notes.

ChuckS 04-06-2020 08:04 AM

Re: MIDI notes out of sync caused by Delay Compensation?
 
IIRC, something like this was a problem when you had high latency plugs engaged on the master. My memory may be flawed.

albee1952 04-07-2020 05:05 PM

Re: MIDI notes out of sync caused by Delay Compensation?
 
Indeed, any latency on the Master Track is NOT compensated for, so step #1 would be to make any Master Track plugins inactive(Bypass does not work for this) and test. Select(Under View>Mix Window Shows>Delay Compensation and look at the numbers across the bottom of the MIX window. Anything showing more than 10-11 samples is going to be a possible cause of timing issues because Delay Compensation works by finding the track with the most latency, and making every other track LATER by that amount. This is not an issue when mixing, but can be an issue while tracking(recording), so if you see big numbers, disable(Make Inactive) the plugins causing the big numbers.

Also, be aware that its possible for erroneous compensation to happen if you have tracks using sends, but those sends don't go anywhere:o(making those sends inactive or removing them solves that problem).

One work-around is to use the original midi as a timing reference, commit the track that the midi is "playing" and then nudge the committed audio file so it lines up with the original midi:o

Starcrash 04-15-2020 11:41 AM

Re: MIDI notes out of sync caused by Delay Compensation?
 
I have just one stereo instrument track and one stereo audio track in the session. I turned off delay comp, no plugs (except the VI), lowered buffer to 128 and still the midi notes end up about 75-100 ms early on the timeline. When I play it back it sounds nothing like the performance. I don't think it's just me playing ahead of the beat because it's way off.

XJENSEN 04-15-2020 12:06 PM

Re: MIDI notes out of sync caused by Delay Compensation?
 
How do you monitor the instrument? Direct or via Pro Tools? Are you playing to a Click Track or to some audio?

Starcrash 04-15-2020 12:35 PM

Re: MIDI notes out of sync caused by Delay Compensation?
 
Thanks, XJENSEN. I'm playing along with a stereo audio track, a bounce of my session I made to take the other tracks out of the equation.


I'll try a few more tests with a click as well.

Starcrash 04-15-2020 12:44 PM

Re: MIDI notes out of sync caused by Delay Compensation?
 
1 Attachment(s)
I just tried it with a click track. As before the midi notes are way early compared to the click. I just rendered a piece of the click and took a screenshot so you can see the result.


https://imgur.com/QlVwbrL https://imgur.com/a/j3aw2iM https://imgur.com/1f257Ue

Starcrash 04-15-2020 12:53 PM

Re: MIDI notes out of sync caused by Delay Compensation?
 
Against the click it was averaging about 220 ms early.


For this test I'm monitoring though built-in audio on a Macbook Pro (no interface). Some regular headphones.

Starcrash 04-15-2020 12:56 PM

Re: MIDI notes out of sync caused by Delay Compensation?
 
Just changed the buffer size from 128 to 1024 and did the test again and it was the same result

Starcrash 04-15-2020 05:20 PM

Re: MIDI notes out of sync caused by Delay Compensation?
 
Just did another test where I used an Instrument Track with NO instrument at all and tapped to a click track. The resultant notes are about 160 ms early to the click!


Is there someone willing to repeat this test? Just record and tap your MIDI or USB controller in time to a click track and then render the click and then zoom in to see if the notes are sync with the click.


I can't figure out what's going on, but theoretically it seems like PT is overcompensating for whatever system delay or latency it has under the hood.


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