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Mavericks audio dropouts "clipIfNecessary"

I've seen a few references to this bug from various points over the last 6 or 7 years, but for varying reasons. I just upgraded my Mac Pro to Mavericks, and all of a sudden I'm getting occasional audio glitches. It's kind of a rasping, stuttering dropout, lasting maybe a second in total. Console always gives me the following...


IOAudioStream[0xffffff8069a7d000]::clipIfNecessary() - Error: attempting to clip to a position more than one buffer ahead of last clip position (9ef19,d4)->(9ef1c,2fc).


Apart from Mavericks, everything else is the same... a MOTU Ultralite 1, connected via Firewire. It was flawless in Mountain Lion. This happens on all types of audio, whether I'm playing a 24-bit AIFF or a Youtube video.


Anyone else encountered this recently?


[Mac Pro 5.1, OSX 10.9.4]

Posted on Jul 4, 2014 4:41 PM

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5 replies

Aug 30, 2014 9:50 AM in response to adrianclark

Sorry I can't help you but I wanted to chime in and say I have the same issue. I'm a musician and have been using a laptop rig with software instruments for many years with 100% success until this started. I'll be playing and the audio will turn to fuzz or drop out for a few seconds, then return to normal. Looking at the Console log I see up to 1500 of these "clipIfNecessary()" messages, all within a few seconds. What's really a drag is that there is no indication what causes it. The log entry right before these messages is sometimes an hour before. What's also making it difficult to troubleshoot is that it only happens occasionally, not on every gig. And, when it does happen, it always happens just that once on a gig – it's never happened twice on the same gig. I am not using 3rd party audio drivers – I use the my MacBook Pro's stock audio output (actually its digital optical output which shares the same stereo minijack).


Things were fine when I first started with my new MacBook Pro with Mavericks this past January. The issue may have started with a Mavericks update. I went to 10.9.2 and now I'm at 10.9.4. The only thing I can think of trying is to roll back to 10.9.0 but I don't know if that's even possible.


When I'm doing gigs I use two copies of Plogue Bidule (an audio & midi routing & processing app that hosts my virtual instruments). No other user apps are running. I always do a fresh restart before every gig and I disable wifi. I have also disabled Notification Center and iCloud since they can start daemons at various times, which might cause a spike in CPU usage and affect my audio apps – this hasn't helped.


I don't expect any real answers here but if anyone knows a different way of troubleshooting other than looking at the Console logs I would really appreciate it.

Oct 29, 2014 6:45 PM in response to adrianclark

I have a Mac Pro Mid-2010 running Yosemite with a MOTU Traveler connected by Firewire, with MOTU's Yosemite-compatible drivers 1.6.64208.


No matter what app I'm using, I occasionally experience dropouts with a series of corresponding entries in the log:

Oct 29 21:31:24 kernel: IOAudioStream[0xffffff8032700c00]::clipIfNecessary() - Error: counted 2 clip more than one buffer ahead errors


This problem also occurred with this same system in Mavericks with a Mavericks-compatible version of the MOTU drivers. I do not recall this happening in Mountain Lion.

Oct 30, 2014 6:14 AM in response to jliechty

jliechty, thanks for letting me know that there are more of us with this issue. Although my error message is not exactly the same as yours ("attempting to clip to a position more than one buffer ahead of last clip position").


Since my post above yours, I've done a lot of googling and have come to guess that Console writing the messages to the log is what's causing the audio interruptions – NOT whatever is causing the messages to happen in the first place! Also, I got a similar interruption in the audio at 12:15AM on a gig once, and saw that there were "powerstat" log files being written every night at that time. In that case, I was able to find a forum post detailing how to suppress those log files from getting written.


A few days ago I reinstalled Mavericks (it went on as 10.9.4 – I haven't updated it yet). So far I've done one gig without incident or clipIfNecessary messages. This means nothing as I've often gone a few gigs without problems only to see them reappear. I'll need to do at least 5-8 consecutive gigs without issue before considering that reinstalling Mavericks did the trick. Before I reinstalled the OS, I updated to 10.9.5 and that did not fix things. Hearing you mention similar problems with Yosemite does not bode well for my continuing with Apple laptops I'm afraid – all my software is cross-platform and I will not continue using a setup that I have to be on edge every time I take the stage. I really hope I (or anybody) can get to the bottom of this. As others have said in similar posts, these issues never happened with earlier Apple OSs. I used an 2007 MBP, and before that a 1.67Ghz Powerbook G4, with almost the same software I have now, over the past eight years - running 10.5 through 10.6.8, and my setup has been rock-solid – until now.

Jul 31, 2015 8:12 PM in response to djjot

I know this is an old thread but I found this issue from Googling around. This has happened to me live three times in a row, and it sounds like my only option is to either buy an older MacBook and downgrade to Mountain Lion, or move away from Apple (shudder.)


I've been experiencing this issue with Mainstage, Cubase, Traktor -- with two different audio interfaces. The commonality between all reports I've seen is the OS -- any version higher than Mountain Lion has this issue. It's not the third party software or hardware, it's Core Audio. Apple can't seem to replicate it so the only reply I've seen is "update the OS" or "it must be some software you have installed" despite it happening with Apple-only software on fresh installs.


Other threads:


Mavericks audio dropouts "clipIfNecessary"

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