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Old 05-03-2012, 08:50 AM
gbevin gbevin is offline
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Default MacMidiTime interrupt overflow


I'm very pleasantly surprised with the feature-set and the overall design of Mobius 2.1 AU. I'm currently integrating it into my Eigenharp live setup for audio looping. When I moved the setup to my live performance laptop (which is less powerful than my iMac), things initially looked fine until I started pushing the CPU load. Then everything crashed and the system logs show MacMidiTime interrupt overflow. From searching the internet it seems that this could be a Mobius bug. Any thoughts about this?


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Old 05-03-2012, 01:47 PM
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Jeff Jeff is offline
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Mobius uses a high resolution timer to accurately send MIDI clocks in tempo with the audio loop. This timer "wakes up" every millisecond and tells Mobius that it may need to think about sending a MIDI clock. If the system is under heavy CPU load Mobius may not have enough time to respond to this wake up signal before another millisecond passes and the timer wakes up again and tells Mobius about another clock tick. When this happens Mobius emits a MacMidiTimer overflow message to the console.

This is not necessarly a bug. Like audio "crackles" this is one of the things that can happen if the CPU load gets too high for the hardware to handle real-time audio.

What were you doing to push the CPU load? It could also be the combination of Mobius functions and tracks you were using that triggered an unusually high CPU load. If you were using any of the pitch shifting functions that often happens.

Also please post the specs of your laptop. If this is a Macbook Air I have had mixed reports about that being powerful enough for Mobius.
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Old 05-03-2012, 01:59 PM
gbevin gbevin is offline
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Thanks a lot for the reply.

I was playing software instruments on my Eigenharp. Mobius wasn't doing anything really, just sitting there idle with audio coming in, no playback nor recording. I know I was pushing the CPU pretty hard though, I'm living on the edge with this setup but it was working fine before adding Mobius in the mix (I'm waiting for the new MBPs to come out to upgrade). What worries me is that it caused the real-time audio render thread to stall for too long, causing the whole application to become unstable. Are you sure that these overflow messages are benign?

The laptop is a 17" MacBook Pro Core Duo 2, 3.06GHz, 8GB RAM, SSD.
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