Audio output problem in Mountain Lion

This worked for me:

If you see red light in the headphone port, plug the headphone into and out of the port

5 or 6 times to flip the microswitch inside. Sound may be stuck in the digital mode.

I have a similiar problem as this. Running Mountain Lion, Originally I had my MBPro Logicboard replaced for a known issue with the video card. Right after I brought it back, I noticed after a few days that my volume icon would grey out intermittently and the audio would stutter, video (netflix, youtube, a physical DVD) would also stutter sometimes with the sound (but not all the time). I returned it back to the Authorized repair center and they could not find anything wrong. They did an internal chat with Apple (some kind of chat just for techs within the Apple network) and Apple said it was software and asked me to set up a new user account and see if the problem occurred within the new user account. After a few days using the new account, it did. Eventually the sound in my main account and the new user account stopped working completely. Their next step after this was to erase and re-install Mountain Lion. I did the erase and re-install and after a day or two with no issues, I'm back to the same stuttering and greying out of the volume icon.

After the re-install, I noticed by going to preferences/sound that I could actually see the digital output and internal speakers switching back and forth when the sound drops out or the icon greys. So, it seems to be something is causing it to switch between the optical output and the internal speakers.

Also, another characteristic of this is that the volume will sometimes be randomly reduced to a low volume, then maxed.

Anyone experience this?

I am having this same problem. Brand new MBP 17" (literally a few days old), and a fresh install of Mountain Lion on a new harddrive. Digital audio keeps swapping in and out for the internal speakers, which is disabling the volume control.

Mine started doing it after plugging into an external USB hub with a couple of drives, keyboard, and tablet attached. Think it could have something to do with the MBP thinking there is an audio device attached? Maybe a faulty peripheral?

Hey Justin, Take your mac to the apple Store. It's DEFINITELY a hardware (logicboard) issue. I took mine in to the apple store and within 5 minutes they diagnosed the issue. If it's extremely intermittent (like mine was) try to get some video of it happening on your iphone or camera, it helps with the diagnosis. But the Apple genius said, whenever you see that, it's usually hardware.

Take care,

Jeff.

That's a total bummer. I was hoping it was a reboot issue like the other folks in this thread. My closest Apple Store is an hour away. I'm assuming you had to take it in, diagnose the problem, leave the computer with them while they order the part/send it out, and then come back for it? How long were you without your machine?

YES! Thank you for posting this, it works.

but2ene wrote:

For me, i've just killed coreaudiod.

sudo killall -9 coreaudiod

After lauch this command in terminal, my headphone work again.

I don't know why...

This works for me as well, but need to do it on each boot!!

Manually delete old files like ones below from

Library > Preferences > Audio (these were outdated - spread the word!)

Library > QuickTIme

CanonMJPEGAVI.component

CanonMJPEGAVIDec.component

CanonText.component

DesktopVideoOut.component

DVCPROHDMuxer.component

DVCPROHDVideoDigitizer.component

DVCPROHDVideoOutput.component

DVCPROHDVideoOutputClock.component

DVCPROHDVideoOutputCodec.component

FCP Uncompressed 422.component

Google Camera Adapter 0.component

Google Camera Adapter 1.component

LiveType.component

macam.component

AmpliTube2DUOLERW.vst

StudioDevilBVC.vst

DVCPROHDAudio.plugin

Sound works on 15" MBP from 2010 !!!!

I followed a poster's advice and after trying 90 things, I simply plugged in/out a set of headphones and it immediately fixed the problem.

Thanks ya'll

Finally, I fixed it and so far so good.

What I did was:

Open a console and type in :

sudo chown -R _coreaudiod:admin /Library/Preferences/Audio

This fix permissions.

Then type in:

sudo update_dyld_shared_cache -force

This will clear and rebuild dyld (dynamic linker)

And finish with:

sudo killall coreaudiod

To restart the audio daemon.

The sound came back instantly and kept working after reboot.

Okay how do you "open a console?" What is a console? Please make this doable for non techies.

Can't believe I upgraded to screw up my MB that's been reliable all these years.

Applications -> utilities -> terminal

On the desktop, make sure that "Finder" is written on the top bar, then click on "Go To", then "Utilities". In the new opened window, double click on "Terminal". You've open a console!

What I found best is to use Onyx which is a system utility for techies 😉 but can be used as custom user.

The problem came back a few days ago and I tried what I wrote but unfortunately, the problem was not solve after reboot, so I restart the audio daemon and ran Onyx. Into Onyx, I ran all the maintenance scripts, and rebuild shared dyldn cache and it's done. I think that maintenance scripts are not designed the best way as they are scheduled to run overnight when, computer are... shut off...😁 I am going to explore what those script do and try to modify schedule.

That fixed it! NOTHING else was working to fix the problem. As soon as I ran that command (sudo killall coreaudiod), it immediately began working.

Strange thing is that the same issue was causing QuickTime to fail opening ANY movie file (with a nebulous -101 error). As soon as I ran the above command, QuickTime began working as well.

Thank you!!

Rick...

Seems like this is happening to a LOT of people over the years.

My MBP will not play out of the internal speakers - the output port is stuck with "Optical digital-out port" selected

Restarting and flushing memory etc has not changed anything, nor has removed outdated pref files.

The terminal command "sudo killall coreaudiod" has not worked

The problem seems to be that the port "thinks" that there is an optical connection plugged in, which is telling the software to be in optical-out mode, this disabling the internal speakers. Something to do with the microswitch inside the headphone port. Wiggling things in the port, blowing compressed air in, and cleaning with a Qtip has not fixed it. I occasionally get the red light appearing. Buying an optical cable and plugging it in and out has made no difference.

Booting up in Windows via bootcamp makes the output work as normal

So whilst there seems to be the hardware issue that the port microswitch is faulty, the problem could be solved in software, by overriding the microswitch

It seems that many people agree that the solution here would be to disable the driver for the optical-out, or force the system to output through the speakers, but as yet I haven't found a way to do this