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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

Sep 16, 2013 7:02 PM in response to Rick Hawkins

Thanks for the comments.


I have been looking through my Library stuff for things that no longer makes sense. I have stuff from 2003 that has not been used since.


Little by little I am dumping stuff that has moved from computer to computer over the last decade.


Its hard to tell if its helped yet, could be the wash job that make my car faster phenomenon.


I will do some testing and get back with the results.


Again, thanks for your comments.

Sep 17, 2013 4:47 AM in response to jimoase

I spent a good couple of weeks doing the same and then decided out that it was still easier to make a backup and decide what I needed rather than what I didn't.


I have a suspicion that its something that doesn't get removed by an uninstaller correctly as I uninstalled every plugin and tool that did any obvious audio/video work before settling on a scorched earth approach. I am a few days into the new system and have put back things like skype and almost all of the audio plug ins I actually use and its still stable.

Sep 17, 2013 6:43 AM in response to Rick Hawkins

Rick.... When I installed Mountain Lion, it was a clean install to an SSD/HDD setup on my Mac Pro 2009. I manually re-installed each program. As far as I can remember, I also re-setup each pref too (except for BBEdit, maybe, whose pref's I copied over).


I also tried installing ML as an "upgrade" on a cloned copy of my original Snow Leopard HD.... Both give me the skip.


Apple seems to be ignoring this. I was asked to send in a bunch of data files and logs, but never heard back. I had submitted a bug report, which they replied to initially, but it's been dead for a couple months now.


If I would have known about this glitch, I probably would have stayed with SL... After spending so much time re-installing the entire system, I don't want to go back to SL at this point.


I can be doing Nothing, just playing music in iTunes, and it skips/stutters. I don't have to be surfing the 'net, or typing or anything.


I do not know if the issue occurrs on my Mac Book Pro 2008 or not because I don't usually listen to music or videos on that one. As far as I know, it doesn't skip.... But for sure the Mac Pro does and without a doubt, the issue did not occur with SL; it wasn't until ML was installed that the skip began.


Can we wait for Mavericks? Will it actually fix anything?? If not, then what?

Sep 24, 2013 10:31 PM in response to JMohr

There is an articel in MACNN http://www.macnn.com/articles/13/09/24/fixes.issues.with.macbook.air.sleep.other .components/


There is an update to 10.8.5 coming out. Didn't see stuttering mentioned. We can hope.


On my MBP stutters last in seconds, cursor stops, beachball comes on.


Do you think if we swapped our Macs with Tim Cook's Mac that the stuttering problems would go away a bit faster?

Sep 25, 2013 6:19 AM in response to jimoase

jimoase, I hope it fixes it, but at this point, don't hold your breath 😁 (joking... I hope)


Apple Closed my bug report. They said it was a duplicate to one (or more) bugs already reported. Maybe I should take that as an encouraging word that they at least know it exists, but the question is, when are they going to fix it? I don't get spinning beachballs when my Mac stutters or skips. It's just a 1/4-second "space" in the song that's playing. It didn't occur with Snow Leopard, I can tel you that!


As an experiement, I tried hooking up a Bluetooth speaker my brother let me borrow... It actually seemed "better", but I wasn't convienced because this portable speaker just made it too hard to tell. My brother was thinking maybe the issue was because of some sort of digital-to-analog conversion issue. I was considering trying Digital Out to see what it sounded like, but I don't have the equipment to do so right now.


Since upgrading to Mountain Lion, I've also experienced random OpenGL errors (NVDA(OpenGL): Channel exception!) which make my screen nearly unreadable, until I restart the Finder or my Mac. That happened again yesterday...


I'm with you... And, yeah if it were Tim Cook's Mac, it would have been fixed ages ago.

Hopefully 10.8.5 will fix these things... Or even Mavericks! PLEASE!!

Sep 25, 2013 8:35 AM in response to JMohr

By gathering enough clues we will pin point the problem.


While watching a video or online video stream when stuttering occurs there is a consistent pattern. The cursor goes dead, key entries stop (sometimes entries are completely missed), audio stops, video stops.

Recovery is cursor movement returns first (sometimes I get the impression cursor movement is the wakeup call), audio restarts contiguous, not missing any audio, with audio stream, video starts in sync after catchingup to period of audio delay, then the typed characters will appear on the screen.


Are you experiencing any of these patterns?

Sep 25, 2013 8:43 AM in response to jimoase

I don't believe I am experiencing the issue quite the same way you are... My cursor doesn't appear to stick and the keyboard does not stop responding. In fact, the mouse and keyboard don't seem to trigger the issue in any way for me (that I can tell). I can have iTunes open, just listening to music, and not even doing anything else, and it will skip.


(Side note, I do have the mysterous jumping mouse cursor... My Mighty Mouse likes do move the arrow on me sometimes. I've tried different mouse pads, etc... It's annoying, but I just deal with it. It doesn't appear to be related to the stutering issue though.)


My Mac is a Mac Pro 2009 2x2.26GHz Quad-Core Intel Xeon - 24 GB Ram.

Sep 25, 2013 9:30 AM in response to JMohr

My Mac is a MacBook Pro, 17 inch, Early 2011, 2.2 ghz i7, 16 GB RAM


I rarely use my Mighty Mouse, but do have the lost cursor thing occasionally while using my touch pad.


Also like you just playing iTunes is enough to experience the stuttering feature. Stuttering with just iTunes audio seems to be on a repeatable schedule and the events are shorter.


Using Safari to access online video results in longer pauses, audio is not lost but the accompanying video does jump after a pause to get insync with the video (I hope that description comes across).


I do a lot of text entry with Pages, TextEdit and Mail. Those pause whether or not I am accessing iTunes or video streams.


Commands to change screens or quit apps is often delayed. That is a feeling thing without a quanitative measurement.


Decades ago I wrote diagnostics for multiprocessor, multi-tasking system hardware and software. We had lots of problems with keeping parallel operations synchronized. Those experiences lead me to believe this is a synchronization problem, resulting from a missed flag or status that is turning into a tight loop that has to be externally interrupted.


Apple's stuff sits on UNIX stuff. If the highest priority events are missed by Apple, cursor or key entry, than UNIX, the processor hog, and Apple, the elegant, are not playing well together.


I wonder did UNIX undergo a change about Mountain Lion time? Enter the old ASSUME deal so no test cases were ever written.

Oct 1, 2013 11:16 AM in response to tttxx

Well I have found a workaround, namely download and install Audirvana, which bypasses core audio for music playback. It is real money (€59) but worth it for me to be able to listen to uninterrupted music without the hassle of downgrading to Lion.

I think there have been a number of different causes of the issues experienced on this thread. I have a late 2009 27" iMac with quad-core i7, which is the same configuration reported by quite a few on this forum and a relatively rare build-to order so probably not to priority for the bug fixers at Apple.

In my case the symptoms were tiny hesitations in the playback on average every 5-30 seconds, but with no pattern I could ever determine. I could see no CPU spikes and never had the graphics freezes or beach ball reported by others. The hesitations were also not correlated with network or disk access that I could see. They did appear the day I installed Mountain Lion.

Usual general troubleshooting made no difference, nor did removing Perian.

Oct 4, 2013 4:39 AM in response to sixfour

I have installed the 10.8.5 update and stuttering still exists. Pauses seem to be shorter, 1...2 seconds verses 3...5 seconds.


Still get the beachball when changing modes of text entry such as changing from forward entry to delete. Again not as often or for as long a period.


As often is defined as didn't happen while typing this message which included my traditional mistakes and retyped entries.


Thanks for the MacRumors information.

Oct 15, 2013 2:35 AM in response to Roland Hanbury

Hmm, I spoke too soon with Audirvana. I still do get audio hesitations. They are larger than before (perhaps 200 milliseconds) but occur at the rate of less than one an hour, rather than every minute, so I can live with that for now. Audirvana does also seem to improve the sound quality (which is after all its primary purpose) even just using the built-in DAC and a pair of M-Audio M-40 speakers. Bitperfect is a less expensive alternative that may have the same effect, but I haven't tried it.

Oct 15, 2013 7:35 AM in response to Roland Hanbury

Maybe its because I am aware of the stutter situation that I pay more attention to sequences that often result in a stutter.


My typing skills are poor so sometimes when a few characters don't appear I question whether those keys were struck. I can reliably confirm that keystrokes are being missed on occassion even at my slow pace of entry.


I use WiFi to connect to the web. Turning off WiFi during keystroke entry seems to reduce the frequency of stuttering but does not eliminate it.


Stuttering has phases of release. A full stutter on my MBP stops cursor movement, scrolling, audio/video and keystroke entry. When returning to normal operation the cursor movement will return before the audio/video restarts. Audio will continue, although delayed, without sound loss. Video will remain froze and then will jump ahead to resync with the audio.


As just happened. I entered two Carriage Returns and nothing happened for several seconds than the cursor moved to this line. One Carriage Return was lost, as you can see.


This is the same kind of problem we experienced on a project in the 1980s when developing multiprocessor, multi-tasking operating systems for super computers.

Oct 19, 2013 11:00 AM in response to Roland Hanbury

This problem has existed for nearly 2 years and multiple updates according to other Apple discussions.


I happen to have an old hard drive with 10.6.8 as the operating system. Booting up on that drive turned my MBP into a very snappy machine with no stalls. I am thinking of making a backwards leap forward. Reliability and speed are what my dollars are suppose to be buying. I vote with my dollars, my next vote will be for reliabily and performances, glitz is too expensive.


Its amazing how slow 10.8.x is compared to 10.6.x.

Sound stuttering after Mountain Lion install

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