Re: [OT] - Music pauses at random intervalls
Re: [OT] - Music pauses at random intervalls
- Subject: Re: [OT] - Music pauses at random intervalls
- From: Bjorn Roche <email@hidden>
- Date: Sun, 6 May 2007 17:17:58 -0400
On May 6, 2007, at 3:29 AM, Roni Music wrote:
Hi,
Some users of my app which, is an audio player, reports that "often
the music will pause at random intervals".
I presume you mean there is a real stop in the audio for at least
100ms or so, so it sounds more like a pause and less like a crackle.
The users have "new Mac Book" computers running (I guess) some of
the lattest versions of OS X.
You should confirm that. I have found some versions of OS X have
different latencies.
The users are playing regularr AIFF files or mp3 files decoded by
QuickTime.
What settings on a laptop could cause this problem?
It seems the operating system is taking over all CPU cycles and
preventing CoreAudio to work OK?
I've never experienced this problem on my 1 GHz PPC or my 2 GHz
Dual iMac
(my app have a quite a few users and the appa have used the same
playback "engine" for severall years).
I know this is sort of "off topic" and the information above is
minimall but still, someone might have some good info to share??
Audio droppouts are usually caused by threading problems (such as the
presence of locks in your audio processing thread), priority issues,
CPU or data starvation, hardware issues, or buffer-size mismatches.
In my experience, locking issues, and buffer-size mismatches usually
result in shorter dropouts that create clicks or crackles (of course,
anything is possible, it just that's what's common). CPU starvation
is easy to check for (ask the user to run activity monitor), and
hardware issues often effect more than one app, but it's definitely
worth finding out what hardware they use. By process of elimination,
data starvation is my guess. Is their drive going to sleep or
something weird like that? It's possible quicktime is reading ahead
in huge chunks, or that it's "tasking" efforts are blocking some
other part of your app? Are your buffers big enough (without being
too big -- they need some RAM left over!) and always available for
reading? I don't know if that's any help, but maybe it's something to
think about.
bjorn
-----------------------------
Bjorn Roche
XO Wave
Digital Audio Production and Post-Production Software
http://www.xowave.com
http://blog.bjornroche.com
http://myspace.com/xowave
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