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Sound stuttering after Mountain Lion install

Dear community,


after having installed OSX Mountain Lion my sound startet stuttering whenever there is rapid movement on my screen.

This includes e.g. window movement, scrolling through image loaded websites or video playback (flash player, quicktime).

A restart didn't help. I'm using stereo output, not digital.


I have connected a second monitor but the problem persists after disconnecting it. Movement on the second monitor also causes the sound to stutter.

My GPU Diode temperature is at 85°C (there is some bug that keeps the GPU under load while a second monitor is connected AFAIK), but I guess it was the same under Snow Leopard.


In Snow Leopard the sound output was always perfect even under heavy load or heavy HDD I/O.


Any ideas?

iMac (27-inch Mid 2011), OS X Mountain Lion

Posted on Jul 28, 2012 5:48 AM

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Posted on Jul 28, 2012 3:22 PM

I am also having this issue as well.


I opened Activity Monitor and noticed that during the stuttering, coreaudiod jumps in CPU usage, often past 5%. I have also noticed graphics lag when this occurs if I'm doing something like watching full-screen video or gaming.


I'm currently experiencing this on mid 2011 iMac 27" as well as a 24" iMac 2009 model I use at work.

1,223 replies

Aug 3, 2012 3:11 AM in response to sixfour

That poster wasn't very specific about which set of updates he has installed.


Ever useful 😝


I suspect he's not talking about an point upgrade for Mountain Lion but rather a firmware update specific to his model of machine.


In his signature he has that he has a "MacBook Pro Retina" which has coincidently had a few firmware updates in the last few days :


http://support.apple.com/downloads/#MacBook Pro Retina


These updates would be specific to the model of hardware so even if you downloaded them they won't install.


I'ld offer to take them apart to see if there's new versions of certain kernel extensions inside but I'm at work. On a Windows machine with 7 zip that cheerfully extracts the DMG as partitions into seperate files (literally I have files with partition type names lol)

Aug 3, 2012 3:14 AM in response to Ivan Clarke1

I've had a look at the posts sixfour linked above.


Looks like the guy is speaking of the recent SMC update for his MacBook Pro Retina that come out in the last few days ago.


Of course the guy wasn't that specific about if he had the previous installed as well nor how long he had it so it could of been any of the firmware updates for his MacBook Pro 😝

Aug 3, 2012 1:41 PM in response to Richard Reid1

Hi, everyone.


I've posted several times on this and other threads/forums about this issue and the dozens of steps I've tried to solve it, including reinstalliing ML several times. There are very few things, if any, that I haven't already done.


If I watch video from any source (Netflix, DVD, videos on my computer, using a browser, DVD Player, VLC, etc.) full screen, the audio stuttering, followed by the video pausing or stopping completely, ALWAYS happens. What's odd is that it may happen one minute into the video, 5 mnutes, 20 minutes. There doesn't seem to be a pattern.


When this happens, no other programs are runniing. The console isn't reporting anything really odd, and everything looks great in Activity Monitor (no apparent spikes in CPU).


The only light I can shed on the problem is this:


If I go out of full screen video and continue watching the movie (or quit and start over, which I have to do most of the time) in a much smaller window, it almost always plays without hiccups for the entire movie! As soon as I try going full screen again, the problem consistently returns.


Therefore, I can only conclude that this issue must have something to do with the video drivers (?) in ML or something else (memory issue? buffering?). I'm not a programmer (obviously), so I'm only guessing.


Because it appears to be random in how long it takes for the problem to occur, is there something in an OS, such as buffers(?), that would cause a "build up" until the problem occurs again. Maybe you can figure out what I mean. 😁


Also, many people mention that they have MBP or MBPR, but that in itself isn't the problem. I have a 2011 iMac, and so do two of my friends. All three of us have the same problem with ML. No 3rd party RAM. And we never had any issues until the day we installed ML.


Any other ideas based on this info?


David

Aug 3, 2012 1:56 PM in response to Lvivske

Rebooting solves the problem...for about 5 minutes, but it always returns as soon as the full-screen video starts.


I haven't had any problem with audio only (in iTunes).


So, could audio be causing the video problem?


If so, logically, if we watched a full-screen video that had no sound (I mean, no audio track), the problem wouldn't occur.


Just a thought. Unfortunately, videos with no audio track aren't so common 😝


Any thoughts? I'm throwing out any ideas hoping that some of the programming experts on this forum will think of something.


David

Aug 3, 2012 2:41 PM in response to tttxx

Glad I found this, so I'm not the only one.


Experiencing this with audio only, videos running fine.


When playing music (iTunes/VLC) I have little cracks every few seconds, this gets annoying.


At first I thought my external HD is broken, but then I tried playing music from the internal HD and got the same problem.


The "10min or so fine then broken"-problem only occurs to me when running speech on some text in Safari.


I upgraded to ML from a clean install of SL (<- no problem in years), but something's not right with the latest OS...

Aug 3, 2012 3:22 PM in response to Lyone

Lyone,


Would you please make a few tests:


1. Try playing iTunes audio only for a while with different audio levels. Does problem occur?


2. Try playing full-screen video with audio (nothing else running). Does problem occur?


If you could try both of these tests with and without your ext. stuff plugged in, this may help narrow the problem down.


Let us know what happens with these 4 scenarios.


Thanks


David

Aug 3, 2012 4:04 PM in response to dcollett.seattle

Videos running perfectly fine - 480p/1080p/4K's - anything.


I rebootet for testing - audio is still a little cracking, but not as bad as it used to be by the time of my first post.


30min of testing isn't that much, I would like to try more, but it's 1am where I live and I need to get up early 🙂


I'll remain in this thread and will post results if I can get any noteworthy.

Sound stuttering after Mountain Lion install

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