Avid HDX latency PTHD vs other DAWs

[kikidi]

Hello,

I'm a new hdx user, maybe you could help me.

Is it possible to have the same low latency for tracking in Logic (or whatever daw) as in PT HD ?

When I record in PT HD, this is perfect I cannot hear the latency. But in Logic, even if I put the lowest buffer, I can hear a little latency, as it was phasey.

I tried to put the lowest buffer inside Logic and also inside the avidaudioserver.app.

Moreover, the buffers change seems to be taken into account only in the avidaudioserver app and not when I change in Logic. Is it normal ?

Also, weird things : Some youtube videos or some wav files (not all) plays under 3/4 output instead of the 1/2 output when I play in firefox or quicktime player.
But when I play in google chrome or in old quicktime 7 player it works fine.

I'm really thinking of formatting and redo a fresh start with my mac :)

Thank in advance for your help !

[BScout]

No.

[Darryl Ramm]

^^^. And the reason why is Pro Tools is talking to the DSP based hardware mixer in HDX directly, and running DSP plugins there as well if wanted. Other DAWS only get to talk to the HDX hardware via CoreAudio or ASIO... which implicitly is going out through latency adding IO buffers to the DAW. And if plugins are wanted there they can't run those on the HDX DSP either.

[kikidi]

Awesome ! Thanks a lot for your replies.

[JCollet]

I know this thread is old, but since I was looking forever for a solution, there is: right-click HDX in audio-midi setup, select "configure device". There you can the the buffer which adds onto your DAW's

[LDS]

Originally Posted by JCollet

I know this thread is old, but since I was looking forever for a solution, there is: right-click HDX in audio-midi setup, select "configure device". There you can the the buffer which adds onto your DAW's

According to the first post, the OP has already tried setting the buffer to its lowest setting. Their experience with Avid coreaudio drivers is similar to a lot of other peoples, I think. Reducing the sample buffer will help minimise the latency, but it still doesn't get HDX or HDN devices anywhere near the latency they have inside Pro Tools, or other low-latency native counterparts like RME or Lynx devices.

Some food for thought. At 48kHz:
- HDX has a base latency of ~1.7ms in Pro Tools.
- HD Native with a 32 sample buffer will have a latency of ~2.5ms in Pro Tools.

When running in Logic with a 32 sample buffer using the coreaudio drivers, they both have a latency of around ~14ms. For some people that will work just fine, but for many people who purchased HDX or HDN to use for low latency monitoring, it is obviously magnitudes worse under coreaudio/ASIO than it is inside of Pro Tools. Just for comparisons sake, an RME HDSPe Madi card will have a latency of ~3ms at 32 sample buffers in both Pro Tools & Logic. To get anywhere near the ~14ms of HDX or HDN running under coreaudio, you would need to set the RME to a sample buffer of 256.

[JamesG602]

Ya but it sounds like the OP was adjusting only the buffer in Logic. You can also adjust the buffer in core audio as stated above. I think default in core audio for the HDX is set to 256.

This will help the latency outside of just changing it in Logic.

[Darryl Ramm]

I would expect setting the Buffer size in Logic Pro is all that is required. Logic Pro makes exactly the same CoreAudio request to the HAL/driver to change the HW buffer size as Audio Midi setup does. I have trouble seeing how else any of this could possibly work and I have some understanding of Core Audio internals.

Sure if nothing is using the interface it might show some default buffer size, but changing that in audio midi setup should not be needed.

[JCollet]

Indeed it’s two different settings, one is logic’s buffer size, one for the hdx driver. If you set logic to 32 samples but don’t touch the hdx driver, recording percussive material will be hard. If you set both to 32 samples you should come to a roundtrip latency of approx 3ms at 44.1 which seems pretty fine to me. Sure not entirely what hdx with PT does but a lot better than the standard 17ms at 256 buffer size…

[LDS]

Originally Posted by JCollet

Indeed it’s two different settings, one is logic’s buffer size, one for the hdx driver. If you set logic to 32 samples but don’t touch the hdx driver, recording percussive material will be hard. If you set both to 32 samples you should come to a roundtrip latency of approx 3ms at 44.1 which seems pretty fine to me. Sure not entirely what hdx with PT does but a lot better than the standard 17ms at 256 buffer size…

There really is only one setting though. It is applicable to every coreaudio interface out there. What you're experiencing is just the awfulness of Avid's coreaudio drivers. I can't stress this enough. They are awful. You don't actually set the hardware sample buffer in two places. You've just left guessing which one might actually have the anticipated effect, and if you're lucky, do it without crashing the Avid Audio Server followed by Logic throwing "Audio Device No Longer Available" messages.

On that same token, you also can't really use the "resulting latency" figure within Logic as an accurate indication of round trip latency. That figure has nothing to do with Logic itself. It is just what the audio interface drivers are reporting as the latency. Bad drivers = bad reporting. The only way to effectively measure round trip latency, which is from DAW out through DAC, back in through ADC back to the DAW, is using a tool like this. Having measured HDX round trip latency dozens of times, I can say with absolute certainty that it is nowhere near 3ms under coreaudio.