SAC/SAW/DMXIS Sample Rate WARNING

[cgrafx]

Wasn't sure if I should post this in the SAC or SAW section, but I've decided to put it here since DMXIS is more live sound plugin related.

A little background

I've had a few show's/sessions where I thought I had everything on my system configured for 48K, only to discover that my files were recorded at 44.1k.

It seemed to be completely random and initially I figured it was just user error, as I didn't discover the issue until many hours after the session and didn't have any direct way to determine what had happened.

Present Day

This last weekend during a long band rehearsal (both Friday and Sunday), it happened again. Only this time since all equipment was left in place from Friday to Sunday I had the chance to do some more detailed investigating.

I discovered the sample rate error when attempting to do a daily rough mix for the band to review. The buildmix created on the band live system when transferred to my work/video system clearly was playing back at the wrong sample rate (We all sounded like chipmonks).

I had the chance to fully review the SAC/SAW sample rate settings and they were clearly set at 48K along with double checking and rebuilding a new mix at 48K.

Same result, the sample rate of the final buildmix while stamped at 48K was playing everything fast. Restamping the header to 44.1K fixed the chipmonk syndrome.

Over the course of the last few days, I've been trying to determine how the sample rate could be getting changed.

The system is a dedicated machine, not connected to the internet, has no superfluous software running on it, limited VST and or other plugins, etc, etc.

The ADA8000's were definitely set to ADAT sync and were locked, the RayDat card was properly set to internal and tracking sample rate settings from SAC. It was also locking the sample rate as soon as the SAC engine would go live.

Solution

What I discovered today was the only other software running on the box, "DMXIS", was messing up the sample rate.

This is the lighting software we use to control our stage lights.

I launch SAC, launch SAW, Link SAW to SAC, Start the SAC engine. The RAYDAT card is now properly locked at 48K.

I launch DMXIS and boom the sample rate on the RAYDAT card has now been switched to 44.1K.

Apparently DMXIS can switch the sample rate of the RAYDAT card even though it is presumably already locked by SAC/SAW.

So, I pull up preferences on the DMXIS software. There doesn't appear to be any setting for Sample Rate, upon closer inspect I find that the ASIO settings page in fact does have a sample rate drop-down, but it is almost completely obscured off the bottom of the preference window and there is no way to expand the window. You can in fact still change the setting, but if you didn't know it was there, you would likely never see the drop-down menu item.

So, for anybody using DMXIS on their SAC rig, if your trying to use the AUDIO sampling functions of DMXIS software don't forget to make sure the sample-rate settings match your SAC/SAW settings or you could end up with recordings that are stamped at one sample rate, but actually recorded at another.

[Bob L]

Great detective work chasing this down... glad it is no longer a mystery.

Bob L

[cgrafx]

Great detective work chasing this down... glad it is no longer a mystery.

Bob L

I hate these sorts of mysteries... Nothing worse than having something go wrong and not knowing why. You can't fix what you don't understand.

Your help with this issue, while it may seem indirect, is much appreciated.

Being able to discuss this problem with you and rule out most other causes was very helpful in isolating the real problem.

So thanks..

[mr_es335]

cgrafx,

...DMXIS...This is the lighting software we use to control our stage lights.

...as a matter of curiosity...why not the Control Track to control your lighting? This is what I hope to do one day. I guess if you require "hand-on" control, then the Control Track may not be the best alternative.

[cgrafx]

cgrafx,

...as a matter of curiosity...why not the Control Track to control your lighting? This is what I hope to do one day. I guess if you require "hand-on" control, then the Control Track may not be the best alternative.

The SAW control track can be used to manage a preset lighting show, but its only the trigger point. You would still need a DMX interface and something to bridge the SAW control track info to the DMX lighting protocols (MIDI to DMX).

In our case, even if I wanted to use SAW's control track we couldn't, because we are not using SAW to play back tracks but instead to record our live performances.

[mr_es335]

Hello,

Got it! Thanks for the reply.