Re: Fighting Classic for CPU in audio callback
Re: Fighting Classic for CPU in audio callback
- Subject: Re: Fighting Classic for CPU in audio callback
- From: Jeff Moore <email@hidden>
- Date: Mon, 19 May 2003 16:21:23 -0700
I should point out that there is an AudioCodec SDK in
/Developer/Examples/CoreAudio/AudioCodecs. Feel free to post questions
about it here.
On Monday, May 19, 2003, at 03:37 PM, Bill Stewart wrote:
I'd use the same priority/policy that we use in the AudioFile feeder
thread - take a look in PublicUtility/AudioFileImpl in the SDK - it
has the code there as well..
BTW - are you bringing FLAC up as an AudioCodec? that would be good
for reasons we'll be going into more at WWDC this year
(AudioUnit/AudioCodec.h)
- look forward to trying this Brian
Bill
On Monday, May 19, 2003, at 02:40 PM, Brian Willoughby wrote:
Hello all,
I have been working on a player for flac 1.1 files (Free Lossless
Audio
Codec). It has been working flawlessly with the feeder thread using
the time
constraint scheduling policy and double buffers of about 1 second
each (less if
there are more than two channels). Typical Window Service
activities, like
fidgety dragging of large windows or extreme magnification in the
dock, have no
adverse effect on the playback.
I just discovered that Classic can cause audio stuttering when an
application
running in Classic saves a file, even one that is only 8K. In this
case, my
buffers may have been only 1/3 second because I was playing to a
6-channel
device - not sure if it was in 2-channel or 6-channel mode.
I have not set the priority or importance of the feeder thread. Is
there a
minimum value I can use which will guarantee that my feeder thread
will win any
battle with Classic? I know that it is best to stay below the
CoreAudio
threads themselves, or else everything will stop working, but it be
possible to
set my player between Classic and CoreAudio.
I noticed the problem running 10.2.6, but I would also like to know
if Classic
has a higher or lower priority in 10.1.5 (and what that priority is).
Obviously, I can avoid Classic if there is no solution, but my hunch
is that it
should not be too hard to beat Classic.
Brian Willoughby
Sound Consulting
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Jeff Moore
Core Audio
Apple
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