Audio Problems with OSX 10.5 Leopard

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I decided to test Leopard today on my MacBook Pro. A nice shiny new copy of Leopard 10.5.2 from the Apple store.

To my horror I found Core Audio overloading nearly constantly (stutters and glitches), even when pushing the latency up to 50ms!! This is terrible, especially when I could happily use 3ms latency with OSX 10.4.11 on the same machine.

I have installed 10.5.2 on a separate hard drive thus leaving my Stable working 10.4.11 drive intact.

Searching the net, one suggested solution was to turn Airport off when running Audio Apps. I can confirm that this does seem to solve the problem, I will be running more tests over the next few days to ensure that this is a good workaround until Apple fix the problem. But it does look good so far.

If you have no choice but to use Leopard, then ensure that Airport is off when doing Audio work :-)

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bertambala wrote:
I've got stuttering in all video and audio applications since upgrading my Macbook (2GHz Core Duo) to 10.5.2.  I've read that it's a USB issue (I use the original USB based SoundSticks), though I haven't bothered to test it.  I never have airport on, so I can rule that out.  Bleh.

Yes, more testing has shown that switching off Airport does improve the situation, it is not perfect.

 In 10.4.11 it is clear that Core Audio has the highest priority on the system, in 10.5.2 other drivers (USB, Firewire, SATA, GFX, WiFi) can interrupt the audio if they experience high traffic. This is not acceptable, we shall see how 10.5.3 improves the situation.

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abbub wrote:
Hrm.  I have 10.5.2 on my 2.33 MBP.  Are you talking about recording, or about listening?  I never have any problems listening to stuff with the built in audio, I never have any problems skyping with USB audio on a logitech headset, and I never have any problems recording on my Presonus.  And the airport is always on.

Thats the same spec MBP as mine. I am of course talking about when using Professional Music software, like Locic Pro, Ableton Live, Reason and even Garage Band etc...

If you have the developer tools installed, simply fire up AU lab and then run an mp3 through a few effects (you'll only need two or three), and the engine will overload and the audio will glitch, even though the CPU use will be in the low 10-15%...

Make sure you have the Wireless active... other wise it takes a while for the problems to show themselves.

In  10.4.11, I can run hundreds of Audio effects and have the CPU maxing at 90% and still have glitch free Audio.

The problems with 10.5.2 is caused by the priority of the Core Audio subsystem being too low, of that I'm pretty sure!