Quote:
Originally Posted by Darryl Ramm
I'm not sure what exactly how you are getting this. Pro Tools actually should be compensating for I/O latency. And it does when I test it.
With my RME Fireface UFX+. A click track, is multi-output: to line Output 3 which is electrically connected to line Input 3, and the click track is also output to bus 2. Track Audio 1 records Input 3, and track Audio 2 records Bus 2. They align within a sample. 96 kHz session but that won't matter. 256 sample IO buffer, but that IO Buffer size is compensated for automatically, along with the conversion latency. Attached screenshot shows the sample accurate alignment. Delay comp should not need to be enabled (it does if you were using HW inserts).
Are you using more complex routing? via sends? Start with a stupid simple test session, not using aggregate I/O. No software plugins or hardware inserts. Make sure you do not have MOTU DSP effects (do any of them have any latency, or signal loops in the MOTU hardware monitoring?), disable all that. Try to reproduce the problem you are seeing with the most trivial test session you can and share it online.
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Thanks for the suggestion, Darryl. I created a minimal session and measure the time delay as 2 ms. Here was my process:
• Create minimal Pro Tools session with no plug-ins except a single instrument to generate a click
• Play click track out through hardware output 8 of MOTU 896mk3
• Cable output 8 to input 8
• Record input to an audio track in Pro Tools
• Compare original click and recorded sound
• Recorded sound is 2 ms late
Attached screen shot shows:
• Original click instrument track
• Committed version of same
• Internal bounce of click (send to internal PT bus and use same as input to a new audio track -- timing is sample accurate with committed track)
• Analog signal recorded as noted above - 2ms late
That seems like way more than it should take to go DA/AD, but it is within an acceptable range and if the delays were consistent, I would go on my merry way. However, my problem is that I am experiencing different delays at different times. With the same session (all the same tracks, I/O, plug-ins, etc.) I have experienced delays between 2ms and 45 ms. Most of the time, it's 2ms, but there are times when I record an overdub and it is obviously out of time. In those cases, when I immediately run a test per the above, the delay is closer to 45ms. Since the results with the exact same session are not consistent, it is very difficult to figure out the cause. The fact that I measure 2ms with my minimal session may have nothing to do with it being minimal since most of the time more complex sessions perform just as well. It is possible that if I spent long enough in the test session recording and listening to clicks, it would eventually deviate as well, I just don't think my soul could endure that.
As all intermittent behaviors, this one is pretty difficult to troubleshoot so any further suggestions are truly appreciated.