MTCoreAudio.framework bugfix release
MTCoreAudio.framework bugfix release
- Subject: MTCoreAudio.framework bugfix release
- From: Michael Thornburgh <email@hidden>
- Date: Wed, 2 Jul 2003 21:42:09 -0700
howdy everybody.
there is a new release (1.1.2) of MTCoreAudio.framework to address a
problem i noticed while playing with my new iSight. :) it also adds
one feature. both items are detailed below.
as always, the framework, two sample programs, full source, and
documentation can be downloaded from
http://aldebaran.armory.com/~zenomt/macosx/MTCoreAudio/
new feature: there is now a +[MTCoreAudioDevice
attachNotificationsToThisThread] method to change the run loop on which
the HAL's notification mechanism runs, as recommended by jeff on dec 6
2002. the AudioMonitor sample application now does this in its main(),
which solves some gui glitches while simplifying the implementation.
problem that was corrected: devices that are input-only AND which pass
NULL in on the outOutputData parameter of the IOProc could cause the
MTCoreAudio IOProc/IOTarget dispatcher to crash, but only if more than
one IOProc/IOTarget was active on that physical device simultaneously.
the cause of this was that i assumed outOutputData would never be NULL,
but instead would just be a valid AudioBufferList* with zero streams
(as is currently the case with all input-only devices to which i have
access, which are USB audio devices). if only one IOProc/IOTarget is
active, there's no problem, but when the second one starts, the
dispatcher will take extra steps to accommodate outOutputData mixing
from the different IOProc/IOTargets. these operations dereferenced
that NULL pointer. this case is now checked for.
the iSight presents a NULL outOutputData to its IOProc, which is how i
found this.
if your application never has more than one IOProc/IOTarget on a
physical device, then you don't need to worry about this. :)
finally, for those who don't know: MTCoreAudio.framework is a
Cocoa-flavored Objective-C wrapper for the CoreAudio HAL. let me know
if you have trouble, questions, or feature requests.
-mike
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