From: Chris Luth <email@hidden>
Date: Mon, 15 Aug 2005 17:10:30 -0800
To: <email@hidden>
Subject: Re: Coreaudio-api Digest, Vol 2, Issue 239
Frank-
Tried it and it didn't fix anything. It still periodically stutters,
coinciding with the update process and with large disk writes.
I suspected originally that it had something to do with the Sudden
Motion Sensor as well. However, it happens when the laptop was on a
solid surface, undisturbed. Severely rocking the machine *does* make
it stop playing for a few seconds, but I don't think the two are
related.
Besides, other people with desktops (including a dual-G5 user) are
complaining about the same issue--see the link I posted earlier to
the Apple Discussion Boards:
http://discussions.info.apple.com/webx?email@hiddenFmb3mj.8@.68aca9a0
also:
http://www.macosxhints.com/article.php?
story=20050623234932431&query=itunes+skip
OK, so if it's something in the OS that's interrupting iTunes' reads
of the audio file, that needs to be fixed. Though I'm not a developer
(I'm familiar with some programming terms but I haven't coded
anything!), something that Kurt Revis said in a recent post here
might help figure this out:
So far I have looked at PlayBufferedSoundFile, which looks
moderately useful, but utilizes Mach calls for VM management.
1) This example is probably overkill for your needs. It's designed
for reading long sounds from a file on disk -- think iTunes. You
can
probably start out by loading your sounds completely into memory,
which is much easier to deal with.
Chris
On Aug 10, 2005, at 3:17 PM, email@hidden
wrote:
Message: 3
Date: Tue, 9 Aug 2005 23:48:52 -0600
From: Frank Vernon <email@hidden>
Subject: Re: iTunes stuttering
To: email@hidden
Message-ID: <email@hidden>
Content-Type: text/plain; charset="us-ascii"
Chris-
Just a stab in the dark here... Have you tried to reproduce your
problem with the Sudden Motion Sensor feature of your PowerBook
disabled? I've had issues with audio playback when this is
enabled on
the same hardware you mention here.
To turn it off:
sudo pmset -a sms 0
To turn it back on:
sudo pmset -a sms 1
These settings are persistent across boots.
-Frank
I played around with HALLab (after building it) for a few minutes.
Pardon my CoreAudio ignorance, but I don't really understand the
data
it's giving me or how to interpret it.
Just as Jeff suspected, here's one thing I noticed after playing
around a bit: I did a File>New>New Input Window, clicked on "Start
IO," and watched the Log to see what happened. When the audio
skipped, a corresponding log entry appeared, similar to the
following:
449626.252741: overload
Again, no idea what this means, but it's a promising lead.
I'm not sure how to hook into a target app. File>New>New IO Cycle
Telemetry Window didn't give me much luck, either: I couldn't
figure
out how to start the monitoring, and no data ever appeared in that
window.
To answer Alex's question: the one that's stuttering is the
internal
drive on my 17" PB 1.67GHz with OS 10.4.2. The drive is 100GB, 5400
rpm, and connected via Ultra ATA/100.
Chris
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