Work Priority

Johneecatt · Post by **Johneecatt** » Fri Aug 01, 2008 2:05 pm

I recently bought an Apogee Duet to use with my DP5.13 (bought after the 1'st, but waiting for the upgrade).

Anyway, there is tremendous crackles 'N' pops on record (through a G5, 10.4.11). I love the sound of the Duet, but I've tried everything to get rid of the snap, crackle, pop. Nothing under 512 was useable (and I just can't deal with that much latency). I'd read that someone tried changing the work priority to medium, and it was better, but not a lot. Then, just for grins, I tried low priority, and just-like-that, I could record at 128 (still got some grit at 64, but I can live with 128).

So, my guru question is, how does the 'work priority' function? And what does it control?

Thanks, Guys

magicd · Post by **magicd** » Fri Aug 01, 2008 2:12 pm

Work priority has to do with how DP claims thread priority within the OS. When the setting is low or medium, DP gives up some of the thread priority and other processes can claim priority within the OS.

You did the right thing, for the right reason, and got the right result. Some audio hardware drivers need more thread priority within the OS in order to function properly. By dropping work priority in DP to a lower setting, you allow the hardware driver more access to the OS threading. The hardware driver works better and you therefore get better overall audio performance.

As a general rule, I lower the Work Priority in DP if I am using any non-MOTU audio interface, or if I am running on a non-Intel Mac, especially if it is a single processor G4 or G5.

Dave

Johneecatt · Post by **Johneecatt** » Fri Aug 01, 2008 2:22 pm

Dude - are you like, a teacher or something? That was a very lucid answer. Thanks.

My G5 is a dual 1.8, so if I mix at, say 1024, is there any necessity to change work priority to mix?

Tritonemusic · Post by **Tritonemusic** » Fri Aug 01, 2008 2:27 pm

Johneecatt wrote:Dude - are you like, a teacher or something?

He's definitely an authority on the subject, if anyone is. MagicD is the one thing you can't find in the manual but should have a chapter dedicated just to him.

kgdrum · Post by **kgdrum** » Fri Aug 01, 2008 2:32 pm

more of DP's magic is due to MagicDave ,then most people realize.

mhschmieder · Post by **mhschmieder** » Fri Aug 01, 2008 3:06 pm

Here's an ironic counterspin on the work priority issue:

I bought Sample Modeling's "The Trumpet" this week, but couldn't run it. No big deal, as I doubt I'll wait any longer than September for a new Mac (just waiting for the next round of updates, as Apple may release the equivalent of a Cube based on some recent rumours).

Last night, I decided to try it on some pre-recorded MIDI vs. in live mode. Still no go. So, it was time to experiment with buffer settings and Work Priority. The ONLY combination that allowed me to render a full track, was buffer size = 512 and Work Priority = High!

I got crackly output while monitoring the recording, but it played back beautifully afterwards.

So, even in the context of what Magic Dave said, this all makes sense, and sheds even more light into how these settings affect the whole audio chain both at the input stage and the output stage.

I typically use buffer size of 1024, or 2048 when I can get away with it, and Work Priority = Medium. Perhaps for regular work involving VI's that aren't rated beyond my computer specs

, I should try Work Priority = Low -- though I rarely have trouble with my RME Fireface 800 within DP these days. Instead. it stops playback, crackles, or jumps, in iTunes!

Johneecatt · Post by **Johneecatt** » Fri Aug 01, 2008 4:17 pm

mhschmieder wrote:Here's an ironic counterspin on the work priority issue:

I got crackly output while monitoring the recording, but it played back beautifully afterwards.

Exactly opposite. Mine recorded crackly, and it was on the track. Thanks for the insight.

cbergm7210 · Post by **cbergm7210** » Sat Aug 02, 2008 5:31 am

still got some grit at 64,

Can you tell me about this "grit"?

I swear sometimes I hear something that I could call "grit" or "fuzz" or "high end harshness" sometimes while tracking with my RME Fireface 800. I wonder if this is the same thing you are talking about.

Is what you are talking about with that reference a very subtle artifact, or a completely noticeable "noise"?

Thanks for the insight.

monkey man · Post by **monkey man** » Sat Aug 02, 2008 5:44 am

666 wrote:
Johneecatt wrote:Dude - are you like, a teacher or something?
He's definitely an authority on the subject, if anyone is. MagicD is the one thing you can't find in the manual but should have a chapter dedicated just to him.

Ha! So true, '6ster.

His greatest asset though, IMHO, is that he's a cool guy.
'Course, the vast knowledge base he's absorbed over the years and his love of old-school methods and gear only serve to make him even cooler.

Johneecatt · Post by **Johneecatt** » Sat Aug 02, 2008 11:54 am

cbergm7210 wrote:
Can you tell me about this "grit"?

I swear sometimes I hear something that I could call "grit" or "fuzz" or "high end harshness" sometimes while tracking with my RME Fireface 800. I wonder if this is the same thing you are talking about.

Is what you are talking about with that reference a very subtle artifact, or a completely noticeable "noise"?

Thanks for the insight.

Mostly, I'm talking about audible crackles, but there's also a bit of high end harshness (kind of...granular...) at 64 buffer that smoothes out (to my ears anyway) at 128.

toodamnhip · Post by **toodamnhip** » Sun Aug 03, 2008 1:01 am

magicd wrote:Work priority has to do with how DP claims thread priority within the OS. When the setting is low or medium, DP gives up some of the thread priority and other processes can claim priority within the OS.

You did the right thing, for the right reason, and got the right result. Some audio hardware drivers need more thread priority within the OS in order to function properly. By dropping work priority in DP to a lower setting, you allow the hardware driver more access to the OS threading. The hardware driver works better and you therefore get better overall audio performance.

As a general rule, I lower the Work Priority in DP if I am using any non-MOTU audio interface, or if I am running on a non-Intel Mac, especially if it is a single processor G4 or G5.

Dave

will audio recorded at a lower work priority have any less fidelity?

kassonica · Post by **kassonica** » Sun Aug 03, 2008 1:38 am

No it doesn't effect the sound quality.

It's only function is how the interface interacts with the threading of the CPU.

toodamnhip · Post by **toodamnhip** » Sun Aug 03, 2008 1:41 am

kassonica wrote:No it doesn't effect the sound quality.

It's only function is how the interface interacts with the threading of the CPU.

So then what if any, is a possible down side to everyone just setting work priority to Low?

kassonica · Post by **kassonica** » Sun Aug 03, 2008 1:50 am

toodamnhip wrote:
kassonica wrote:No it doesn't effect the sound quality.

It's only function is how the interface interacts with the threading of the CPU.
So then what if any, is a possible down side to everyone just setting work priority to Low?

Well as I understand it Motu interfaces (and drivers) are written to to take full advantage of the threading of information to the CPU and work better on the high setting. If you have more than one CPU it is recommend to do so.

I found that high was the best setting with the Motu 828mk2 however when I bought the RME it works MUCH better on medium than high.

Some interfaces and drivers are not optimized very well with DP it seems so they recommend that you don't use the high setting.

But there was a thread about this a while back and magicd himself said in a post that it does not effect the sound in anyway if my memory serves me.

jlstcui · Post by **jlstcui** » Sun Aug 03, 2008 2:31 am

Hmmm. I did a bit of DP6 manual reading the other day, and though I haven't yet installed the new version (I'm happily running 5.13), I did decide to apply one of the manual's general suggestions: change work priority to "High."

Since then, I've had considerable trouble getting any decent number of VI's to playback together properly. I'm thinking of trying "Medium" again, if not low.

I run an older MOTU audio interface, the 1224. Is it possible that I should now be thinking of trading up to a newer interface, and if so, which would be best?