HDX tracks record 21 samples late

[Matt Hepworth]

UPDATE: Partial resolution. Issue traced to TRS outs on HD Omni.

Would another HDX user please post results as well?

I'm trying out an HDX as a possible replacement for one of our HD4 Accel rigs.

In testing the system I'm noticing that a track recorded (96k session) records 21 samples late.

This is when patching out from a single output to input on a second track (taking a snare hit and recording it back in). I expect the system to be in time.

I opened a ticket with AVID and they're saying that output latency is not compensated for unless using a hardware insert. I'd kind of taken that as being accurate for several years, but it doesn't make sense that the output delay is not compensated, as that would mean that the entire recording and playback process is uncompensated for the latency occurring from at least one part of the conversion. Punching in while monitoring a delayed track repeatedly would exaggerate that difference, would it not?

Forgive the ignorance here, but I cannot wrap my head around it. The system should be compensating for the latency on every pass.

PT 12.4
HD I/O Omni
HDX
Delay comp ON (32 samples delay, if off)
Input and Output Delay Compensation both ON
96kHz test session
10.8.5

[JFreak]

If it's not a hardware insert (that is set up properly in the i/o setup window) there is absolutely no way PT software can guess what you're trying to do. Say, you send from output 8 and return it to input 7, PT has no other choice than to expect output 8 going somewhere and input 7 being separate from that. Therefore, no compensation. It has been like that forever.

[JFreak]

Good thing here is that you have now measured your DA/AD converter roundtrip latency :)

[Matt Hepworth]

And that's what I'd thought initially (and taken for granted), but if that was the case all musicians would be hearing and working off uncompensated latency. There is always output. It doesn't matter if it's coming back to the input. Input is always compensated, output certainly should be as well.

If the output converter latency is truly not compensated ever, that means you would have compounding drift every overdub, if you're monitoring the take before (i.e. layers).

According to this everything we hear from ANY output through PTHD is not compensated for.

Surely I'm not crazy, right? ;-)

[JFreak]

It is "ever" compensated but you need to set up a hardware insert for it in the i/o setup

[JFreak]

Compensation in this case means delaying other inputs by the amount hardware insert's output takes. And you can even set additional compensation if for example you have read specs of your "reverb box abc" that says its ADDA takes 2.5 milliseconds

[propower]

PTHD Knows exactly what interface you are using. There are only a few possible ones and the I/O panel knows them all - in HDX's case these are AVID I/O and OMNI. PTHD knows exactly what the output delay of these are. If you use 3rd party I/O you can have issues but many are designed to match the AVID I/O and thus not have issues.

Every musician has no choice in an all AVID rig but to listen to the output of PTHD through an AVID interface. To assert that the program is just not going to compensate for this delay to the headphones is just silly. If I put down a drum track - and overdub a guitar that is perfectly in time with what I heard - PT will just put this new track at some other time since it won't account for the output delay to the musician. That's untenable.

I have also measured this loopback performance for years - HDN, Metric Halo ULN8, (a friend of mine did the original Apollo) on PT 10, 11 and 12. They are all perfect - no loopback error.

I have never measured HDX but if it really does not compensate for a simple loopback - that would be something to talk about!

[propower]

Soapbox on...
PS-- this is one of the glaring misses in PT Vanilla - always has been.

There is no simple way to compensate for 3rd party hardware delay. Studio one has it, Logic has it, Cubase has it (those are just the only ones I have used). Its just a simple number you put in on the preference page for the driver. One simple number. In PT Vanilla and 3rd party interfaces that are not correctly compensated for in PT you have to use the DDMF MetaPlugin to do this or move tracks manually. - rant over - soapbox to off...

[Matt Hepworth]

Originally Posted by propower

To assert that the program is just not going to compensate for this delay to the headphones is just silly. If I put down a drum track - and overdub a guitar that is perfectly in time with what I heard - PT will just put this new track at some other time since it won't account for the output delay to the musician. That's untenable.

Exactly. Which is why I'd opened a ticket with AVID. Their aswer, unfortunately, supports my statement and confusion.

At least if I'm crazy I'm not alone. :-D

[Rich Breen]

So just to be clear here - you're talking about throughput converter delay of 21 samples at 96k which is about 220 nanoseconds, correct? I think we can all agree this is beyond our ability to hear in terms of musical timing, no?