Re: question about CoreMIDI & cocoa
Re: question about CoreMIDI & cocoa
- Subject: Re: question about CoreMIDI & cocoa
- From: Stéphane Letz <email@hidden>
- Date: Fri, 1 Oct 2004 21:21:07 +0200
Message: 6
Date: Fri, 1 Oct 2004 07:08:07 -0700
From: Doug Wyatt <email@hidden>
Subject: Re: question about CoreMIDI & cocoa
To: CoreAudio API <email@hidden>
Cc: Khamba Staring <email@hidden>
Message-ID: <email@hidden>
Content-Type: text/plain; charset=US-ASCII; format=flowed
Every process with a CoreMIDI client in it has its own MIDI input
realtime thread. In a lot of simple cases, it isn't that horrible to
block it.
It's often not like an audio plug-in where your code is just one of
many things that happen on that thread, and where blocking can cause an
I/O glitch. If an app blocks its own input thread, the worst thing that
happens from a system performance point of view is that you've added a
few dozen microseconds of thread-switch overhead -- not a killer -- and
your input is no longer arriving as close to instantaneously as you
might like.
If you're writing an AudioUnit, on the other hand, please disregard
everything I just said and do not block the MIDI input thread.
Doug
I remember old threads (january/february) when Jeff Moore explicitly
advised to never block in a real-time (= time constraint) audio thread
because this could disturb the scheduler.
Is this only because audio threads are *periodic* based time constraint
threads? and not the Midi I/O thread ?
Thanks
Stephane Letz
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