Quote:
Originally Posted by Dax Productions
Darryl this is the problem. 20 samples is pretty close. It’s close enough that I can insert something on a one track instrument and not be worried at all. I have my 1176 on my vocal bus on every mix I do. In my case it’s 62 samples early at 44.1. Not enough to sound out of time, and for that situation I don’t have to worry about comb filtering with parallel elements.
The problem is as soon as you want to do any parallel processing. 20 samples will have bad, glaringly obvious comb filtering if I want to use my adr compex as a drum back buss. It needs to be zero samples.
I did try the RTL app and it does confirm that the driver reported latency is slightly more than the actual recorded latency. 62 samples at 44.1, and similar, but not far off numbers for other rates.
My current interface is a Behringer 1820 but I have had similar “over compensation” with UA, Motu, and focusrite interfaces.
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I am not defending it, I'm just saying what I measure. And I understand the impact. But those negative offsets only happen for me with interface digital ports, where the I/O is faster than Pro Tools is either naively just calculating or is calculating maybe with help of driver latency info. It *seems* Pro Tools may be just calculating 2 x IO Buffer size + 157 samples for my measurements with a Fireface UFX+ at multiple sample rates and IO Buffer sizes - with ignore errors *not* checked). I'm curious if you see the 2 x + 157 (remember not to check ignore errors). And it's not like I'm running an interface that is a slouch at conversion times.
What *I* don't see is wildly negative numbers for an individual insert, or problems with multiple inserts chained, or behavior that is inconsistent and changes and I know other folks are reporting seeing that, and it would be really good to try to work out why or reproduce the insanity on other systems. For me Pro Tools can be off a little, but all consistent with the likely speed of different conversion paths in the interface, and its all self consistent whether I'm using RTL measurements or letting Pro Tools do it's thing then measure how far out it is/correct it with the funky H/W insert menu. Again for all practical purposes I don't get negative values overall for an inset... e.g. on the rare occasion I say use an Eleven Rack as an insert it's latency far overwhelms the ~-20 samples Pro Tools sits at though all the digital connections to get to the Eleven Rack, so I end up sliding it forward again with the H/W insert delay setting. Again, just saying what I see, I'm very curious to try to work out what the heck is going on for other users.
And regardless the UI/UX is awful here, it all needs a serious rework.
If I shared a spreadsheet with you would you be willing to add your measurements to that sheet using Pro Tools and RTL Tool for your interface?