I'm running Logic 8.0.1 on a new 20" iMac, 2.4GHz Core 2 Duo, 4 gigs RAM. I stream BFD samples from an external Western Digital 250 gig drive connected via Firewire 400. All audio is recorded to/streamed from an external LaCie 320gig drive connected via Firewire 800.
I'm currently running 10.5.2, have installed all relevant updates including the latest Pro Kit update and other "Pro Application" updates. This issue was present in all versions of Tiger, with or without any and all updates.
I've tried streaming audio and samples from all combinations of internal/external drives. To no avail.
This issue happens every time I load a new project into Logic. I'll try and describe it as accurately as I can.
While playing back, when the playhead encounters the beginning of a region on a track that's previously contained no regions, one of the cores of my CPU spikes to 100%. Usually this doesn't cause a full overload and things continue fine, however, if the playhead encounters two such regions, for example, a harmony guitar solo, or a new doubled guitar line, playback stops and I get an error dialog stating the audio engine was not able to process all of the audio information in time. This is consistent and reproducable in every project file I've got. There are no bit depth, resolution, or any other mismatches. On occasion, I've had this happen with only one region being introduced.
If I turn off overload messages, playback simply stops when the spikes occur.
Now, when this happens, if I move the playhead back a bar or so and hit play, it plays through perfectly with no discernable increase in CPU usage, and no more problems, unless another such group of regions is encountered. Additionally, if I load such a project, and place the playhead somewhere after the beginning of these regions, while they're playing, this also does not happen. It's only when the playhead encounters the beginnings of these regions for the first time. I've tried slightly staggering the beginnings of the regions, experimenting with fades, automated mute on/off, etc, all to no avail.
My projects tend to consist of one MIDI track, with BFD 1.5 plugged into the track for drums, multiple audio tracks containing various guitars and bass, perhaps a virtual instrument or two for audio or apple loops. That's usually it.
I'm linking to a screen grab with some descriptive text overlayed to try and better illustrate things. You'll notice I've highlighted a couple of areas. The first one, normally I don't get an overload, although I have once or twice. The second highlighted area, it happens everytime I play the file (for the first time after it's loaded). As I said earlier, if, before an overload occurs, I position the playhead any time after these regions begin, I do not get the overload. I grabbed this while the song was playing so you could see the CPU meter under normal playback. Appears to be plenty low enough.
I apologize for the length of this post, I'm trying to include all the info I can think of.
BTW - I use an M-Audio MobilePre USB interface, however, this issue happens either with this interface, or using the built in audio of the Mac, with the USB device disconnected and machine freshly rebooted, so I'm sure that's not the issue. Also, after the first playback (and subsequent overloads), playback seems to be normal. If I close the project and reload it, however, it's right back to square one and I get the overloads.
This seems to be a pretty widespread issue. On the Apple support forums (which Apple doesn't seem to read), there are multiple threads about this, some with thousands of views and hundreds of posts. So I'm sure it's not just me, LOL!
Here's a link to the screen grab...
I appreciate any help you can give on this....