Distortion or droputs in monitored audio while tracking

[O.G. Killa]

Hi All,

I did a search and found some posts referring to HDX with PT10 that had a similar problem, but it was on playback, not on tracking. So I think this might be a new/different issue.

Here are my computer specs

Brand new Trash Can Mac (only about a month old):

3.5GHz 6-Core Intel Xeon E5
64GB RAM
Yosemite 10.10.3
Pro Tools HDX2 (two DSP cards) version 12.0.0
Magama 3T Thunderbolt Chassis
Prism ADA8
2x Avid HD I/O 16x16
ICON 24 Channel D-Command ES

Everything is brand new, installed and setup everything about a month ago.

Here's what happens:

With medium to large sessions (at 48KHz/24bit) that have a lot of audio tracks in them (around 50+), when tracking at least 20 or more new tracks that have HDX DSP DigiRack EQ7 and Dyn3 plugins on them, the audio coming through the tracks that are being recorded intermittently becomes distorted (the distortion is like a sampling rate or bit rate problem type of distortion) or the audio just completely cuts out entirely. The audio being recorded is unaffected, I can see the waveforms showing up.

The audio coming through the record enabled tracks will continue to either be distorted or completely gone until I make all the plugins on the record enabled tracks inactive or I restart protools. If I do not restart protools once this behavior starts, within a few minutes protools will crash. I've lost several takes of audio because it crashed in the middle of tracking.

Also I'm not sure if this effects it, but I'm sending audio out several different physical I/O outputs for cue sends too.

Of course this only seems to happen to me when tracking medium to large sized orchestra. So it is quite embarrassing to have to tell 40 musicians the computer crashed while they were recording and I lost that take... not to mention the producers/composers getting annoyed at the time wasted dealing with Pro Tools.

This doesn't seem to happen when I'm tracking only a single track or a small number of tracks at once. It's when I'm tracking 20+ tracks of audio into session that already have a lot of audio tracks in them. And it only happens when I'm trying to use DSP plugins on the record enabled tracks to get a sound while tracking.

I have tried changing the H/W buffer size but that had no effect. Repairing permissions had no effect.

Has anyone else had similar experiences tracking large projects on HDX?

[Shan]

O.G. Killa, the H/W Buffer is used to handle host based processing, which your post mentions you're using only DSP. Here are the host based processing criteria:

Originally Posted by Pro Tools Reference Guide

Hardware Buffer Size

The Hardware Buffer Size (H/W Buffer Size) in the
Playback Engine controls the size of the buffer
used to handle host processing tasks such as pro-
cessing with host-based, or “Native” plug-ins.

• Lower Hardware Buffer Size settings are useful
for improving latency issues in certain recording
situations or for improving certain system per-
formance problems:

• On all Pro Tools systems,lower settings re-
duce MIDI-to-audio latency (such as when
playing a virtual instrument live and monitor-
ing the instrument’s output). Lower settings
can also improve screen response or the accu-
racy of plug-in and mute automation data.

• On host-based Pro Tools systems, lower set-
tings reduce all input-to-output monitoring
latency on any record-armed tracks or Auxil-
iary Input tracks with live inputs.

• On HDX systems, lower settings reduce mon-
itoring latency that occurson tracks that have
one or more Native plug-ins. Lower settings
can also improve the accuracy of MIDI track
timing on systems without a MIDI interface
that supports time stamping. Lower settings
also improve MIDI track timing on tracks us-
ing MIDI virtual instruments that do not sup-
port time stamping.

• Higher Hardware Buffer Size settings are useful
for sessions that are using more Native plug-ins
for playback. These settings allow for more au-
dio processing. They can also be useful to re-
duce errors on machines that require a higher
buffer size.

Since you changed the H/W buffer during your initial trouble shooting steps with no change, I'd try a few more things. The next trouble shooting steps I would recommend is changing the number of Host Processors and the CPU Usage Limit. Both can be found in the Playback Engine settings. I'd also reseat the cards and check the cabling going from the I/O to the cards.

[29CountsNY]

Originally Posted by Shan

The next trouble shooting steps I would recommend is changing the number of Host Processors and the CPU Usage Limit. Both can be found in the Playback Engine settings. I'd also reseat the cards and check the cabling going from the I/O to the cards.

OP is on version 12 and those options no longer appear in the playback settings as of version 11.

[Shan]

Originally Posted by 29CountsNY

OP is on version 12 and those options no longer appear in the playback settings as of version 11.

You're correct. I assumed PT 10 was on the workstation from his first sentence. Thanks for pointing that out.

[29CountsNY]

No problem, wish I had more to offer.

[Shan]

I'd reseat the cards, cables, and trash prefs. Hopefully someone who's experienced this and sorted it out can chime in.

[Drew Mazurek]

Do you have other DSP plugs to test? Would be good to know if it's plug specific. Obviously, it should work with the stock ones, but isolating variables is always good.

[Audioartist]

Have you checked with digitest that all dsp's are ok?

[O.G. Killa]

Originally Posted by Shan

O.G. Killa, the H/W Buffer is used to handle host based processing, which your post mentions you're using only DSP. Here are the host based processing criteria:



Since you changed the H/W buffer during your initial trouble shooting steps with no change, I'd try a few more things. The next trouble shooting steps I would recommend is changing the number of Host Processors and the CPU Usage Limit. Both can be found in the Playback Engine settings. I'd also reseat the cards and check the cabling going from the I/O to the cards.

They are not in the Playback Engine settings for Version 12 of HDX. Here are the choices I have and the settings...

Playback Engine: HDX (other options are PT Aggregate IO, Built In Output, and HDMI)

H/W Buffer Size: 128 Samples (Choices range from 64 Samples through 1024 samples. I have tried 256, 512 and 1024)

Host Engine: Ignore Errors during playback/record (I have this unchecked)

Number of Voices: 512 (Other option is 256)

Sample Rate: 48KHz (options are all the usual)

Video Engine: Enable (is not checked)

Disk Playback Cache Size: 20GB (options range from 256MB to 60 GB)

Those are the only option in the playback engine window for HDX version 12. You can no longer choose how many host processors you want to use nor can you change your CPU limit.

Also to clarify... I am using DSP plugins on the audio tracks that are record enabled since there is STILL no way to use Native plugins on audio tracks while recording with PT HDX. But the audio tracks in the session that are just for playback are using Native plugins... which is why I tried messing with the HW Buffer... but it didn't do anything... also the only tracks that had any audio problems were the tracks that were record enabled with the DSP plugins on them. All of the native tracks were playing back with no problems throughout this entire situation. I also forgot to mention I tried taking the tracks out of record and putting them back in again. Problem persisted.

[O.G. Killa]

Originally Posted by Drew Mazurek

Do you have other DSP plugs to test? Would be good to know if it's plug specific. Obviously, it should work with the stock ones, but isolating variables is always good.

That is a really good idea. The only other plugs I have that are DSP are the Sonnox ones. I didn't have time to swap out all the plugs with Sonnox on the past few sessions this has happened to me on. But I will try that next time it starts happening.