Low Buffer CPU Optimization

[lesbrunn]

This is super, but why is it only for Mac? That is unfair. I would have held on and released it at the same time for both platforms.

[weezul]

The only thing I can think of, is that their implementation of Core Audio was broken this whole time. I've always been able to operate at 32 samples in any DAW, in macOS except Pro Tools. It's always just completely frozen when record-enabling an instrument track at anything below 128. Now it operates how all the other DAWs seem to at these latencies, at least close to. Still has the usual overhead compared to others but it's definitely way way way better than it was (PCIe RayDAT). If you or anyone else is interested enough, I will install Pro Tools to my windows partition and try it. People have been complaining about this below 128 problem for so many years, and it seems like they finally had to face it head on and fix it for the Carbon maybe?

[lesbrunn]

Originally Posted by weezul

The only thing I can think of, is that their implementation of Core Audio was broken this whole time. I've always been able to operate at 32 samples in any DAW, in macOS except Pro Tools. It's always just completely frozen when record-enabling an instrument track at anything below 128. Now it operates how all the other DAWs seem to at these latencies, at least close to. Still has the usual overhead compared to others but it's definitely way way way better than it was (PCIe RayDAT). If you or anyone else is interested enough, I will install Pro Tools to my windows partition and try it. People have been complaining about this below 128 problem for so many years, and it seems like they finally had to face it head on and fix it for the Carbon maybe?

OK. I'm interested.

[daeron80]

Originally Posted by weezul

it seems like they finally had to face it head on and fix it for the Carbon maybe?

That's the simplest explanation. Whatever finally lit a fire under them, I'm glad! Recording multiple tracks with plugins at 32 HWB now with my Trashcan/HDN/Omni. Best I could do before was 64, and that was a little unreliable, even with only one track in record. I'm a happy man, now.

BTW, my Windows machine, which uses a Saffire (over the slower version of firewire!) has lower latency at 64 than my Mac/Omni did. The all powerful Mac has finally caught up.

[weezul]

Okay so that was particularly brutal, identical hardware to my MacOS boot, RME RayDAT at 32 samples, RX580, i7 6700k.

Almost brand new W10 install, set to high performance mode:

https://imgur.com/a/tFlwbAW

After installing PT, the meters are pinned at 100% at 32 and 64 buffer. Before even opening a session. Opened a session, added a master fader, click, 4 inst tracks, 4 audio tracks. Not even got round to putting on Mini Grand or any plug ins at all and it's an absolute wreck. Graphics slow to update, absolutely insanely bad. Even at 128 and 256 the CPU usage is absolutely sky high. Never seen anything like it, even back when I used windows with this RayDAT in Pro Tools 10!

Of course, reaper at 32 samples was fine. A few audio tracks, the click, some ReaSynth all record enabled and playing through my midi controller, smooth as butter. Not really sure what the hell is happening here but it's completely unusable. Also went back to classic, no change. Also turned off multiclient asio, disabled all WDM devices for the RayDAT, anything I could think of. Still the same behaviour. CPU getting hammered before even opening a session.

[daeron80]

So, apparently un-optimized for Windows, then. Good to know. I'll hold off on installing at home until the .1 or so. Was looking forward to trying the Audio-to-MIDI on some of my melodies recorded on the go with Spire on my iPhone. Oh, well.

[Darryl Ramm]

Not sure what the point of all this is... there was no claim of small IO buffer performance improvements on Windows... and as for running tests on Windows... let’s start with if the system running the tests are fully optimized including CPU priority and affinity tweets (excluding Core 0,1 from Pro Tools). Unfortunately known necessary things to get decent performance on many Pro Tools Windows systems. (And that I expect *is* something that Avid should be helping make easier to set up/productize in Pro Tools).

And when discussing performance can folks please be careful to talk about Windows Task Manager etc. meters and not the stupid Pro Tools CPU meters. The issues/uselessness of those meters has been flogged to death on DUC and elsewhere.

All this might have been done for the tests above... but folks here cannot guess.

[weezul]

I have just tried the affinity tweak,it makes no difference.

And my screenshots are showing the Windows CPU meters as well.

Happy to try anything else you want to suggest, but it seems to me that something is up with the Avid Audio Engine. It's after this dialogue line on the splash screen that the CPU usage increases dramatically. An install with no load at all shouldn't behave like this. I'm more than familiar with the issues of instability over the years having used PT since v7 on windows, through USB, FW, and then finally PCIe, only moving to MacOS at v12. But this is different. The CPU usage is very high as soon as the app opens, in the app and in Task Manager. It's not the spikes of years gone by from things like hyperthreading, bad realtime performance, or plug ins.... There's no plug ins installed in fact, just what comes with the Pro tools installer, and the Air Instrument Pack. I've trashed prefs, checked for PCI conflicts between graphics and the RayDAT, the affinity change, turning off speedstepping and hyperthreading, have no wifi to disable, onboard audio always disabled, raydat drivers are current, W10 is current. This behaviour isn't even at the stage where it can be influenced by outside activity. There's no session open, nothing record-enabled....

[Darryl Ramm]

Ugh Weezul, my apologies for replying before reading your posts and looking at your screenshots more carefully. I completely missed the "before session open" stuff. Literally a completely under-caffeinated post on my part. Maybe too focused on making my own point about I wish Pro Tools on Windows at least included some attempts at setting up CPU affinity.

That behavior is not good. And I would not expect the CPU affinity stuff here to help at all (and it should just help reduce CPU errors anyhow not the CPU burn like this). Does this seem like new pathological behavior to you? vs. past releases that did not go crazy at a small IO buffer size with no session open? It does to me, with a quick test between Pro Tools 2020.5 and 2020.11 on Windows 10 just using ASIO4ALL with a crappy interface I see huge difference in idle/no session open CPU burn between these versions at a IO buffer size of 64. Almost none on 2020.5 as expected and similar to you do on 2020.11. And CPU consumption on 2020.11 continues as I open a trivial session. No third party plugins installed. CPU consumption showing up on Windows and in Pro Tools meters.

Who else is seeing this? This may need it's own thread.

[JingleDjango]

I would expect to see similar low buffer optimization on Windows if and when Carbon is qualified for that OS.