Audio through HDMI cuts out after a while, "Sound assertion failed" in kernel.log

Discussion in 'Mac OS X Lion (10.7)' started by chordoflife, Aug 12, 2011.

  1. chordoflife macrumors newbie

    Aug 12, 2011
    Hey guys. I've been having trouble with a mac mini (Mid 2011). Audio through HDMI cuts out after a little while. It's running OSX 10.7. The Mac Mini is the $599 unit.

    Here's some more detail:

    I've got it hooked up to my Sony BRAVIA HDTV (also this year's model) via HDMI, with audio configured to be delivered via HDMI to the TV alongside video. Initially the audio will play through my TV, but after an hour or two of watching something, it will cut out, and there will be no more sound coming out of the TV from the mac. Ultimately, the only way I can fix it is to reboot the Mac Mini. I've also observed that at about the same time sound cuts out, the following error message appears in kernel.log:

    Aug 12 19:21:40 joshs-Mac-mini kernel[0]: Sound assertion "0 != result" failed in AppleHDAWidget at line 3957 goto handler
    Aug 12 19:22:10 --- last message repeated 5 times

    As far as I know, assertions failures usually mean software problems (bugs). I suspect I may be encountering a kernel-level bug in Lion, as this error message is showing in kernel.log.

    The following is a list of diagnostic steps I've taken:

    - I've double-checked the sound output device in preferences. It didn't spontaneously change from SONY TV (HDMI) after sound cut out.

    - I've tried changing output to the internal speakers. It plays sound from the mac mini (as expected). When I change it back to HDMI, still no sound from the TV.

    - I've tried turning off and back on the tv. No effect.

    - I've tried unplugging and replugging the HDMI cable. No effect.

    - I've tried replacing the HDMI cable with two other alternates. No effect.

    - I've tried other HDMI inputs for my TV. No effect.

    - Note: I've got a ps3 and xbox360 on the TV that has successfully used the HDMI inputs and cables tested on. They've never had this type of problem, so I don't think there's a problem with the TV.

    - I've tried rebooting the mac and resetting the "PRAM" (Command-Option-P-R before the grey screen on bootup). Sound still cuts out after a while.

    - All updates are applied.

    Does anybody else have any ideas about what I could try to fix this?

  2. Madd the Sane macrumors 6502a

    Madd the Sane

    Nov 8, 2010
    Wirelessly posted (Mozilla/5.0 (iPod; U; CPU iPhone OS 4_2_1 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8C148 Safari/6533.18.5)

    Send a bug report to Apple.
  3. anotherpaul macrumors newbie

    Aug 19, 2011
    There is a huge problem with Apple's implementation of the sound outputs; very strange as Apple had touted that the Apple computers are the "best for music".

    In hdmi, the right channel cuts out sporadically; have read a post somewhere someone said that it was the left channel, but on mine, it is the right channel.

    Mid Mac mini w/8 gig ram & fink package loaded.

    Today, I connected the "headphone out" to desktop speakers & found that the Mac would not recognize the speakers nor the headphones when that was used.

    Looking at the sound preferences, the initial items I see were the optical out & hdmi out; so I selected the optical out because of the problems with hdmi. Getting sound off & on; looking at the sound pref again I see that the listed "optical" had changed to headphone but not permanently since it did flash on & off.

    Somehow after the connections to the headphone jack was disconnected, the "internal speakers" showed up where it was headphone/optical before; the hdmi is always listed probably because the monitor (lg ips226v) was connected via hdmi.

    After some minutes with the speakers connected, the connection now is "stable" as listed as the headphone out. Don't know what would happen the next time I boot up the Mac mini. Apple has a big problem that they need fix since their output ports, both headphone out & hdmi audio, sensing isn't stable; may be better if the possibilities were listed rather than being variable where ports are constantly monitored & switch to what it thinks is connected.

    I had thought the headphone out was busted earlier because of no sound but think that it was the default to hdmi audio; my Mac mini is only 3 weeks old.

    Hope this helps in understanding the crappy Apple audio process even if it doesn't solve the problem.
  4. err404 macrumors 68020

    Mar 4, 2007
    The digital sound output on Lion has some bad bugs. The previous SL build had similar issues and was quickly patched. I was hoping that 1.7.1 would include the fix, but the problems remain. I have seen some threads from users copying files from SL to fix the issue. I have not tried it myself.

    If you are playing a video that uses DTS/DD passthrough, try downmixing to stereo until the issue is fixed.
  5. koonom macrumors newbie

    Dec 12, 2011
    I am running into the same problem, at the beginning i was thinking it might be the hardware issue, but now i think it's the software bug. my situation is even worse, the sound cut off just after i reboot the machine.
  6. PJJP macrumors newbie

    Jan 27, 2012
    I have a 27" iMac hooked up to a 2nd monitor thru a Samsung all-in-one home theater system that had a Vizio LCD tv hooked up. Problem arose when I switched out the TV to s Sharp 70" LED.

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