Audio sync issues

Discussion in 'Apple TV and Home Theater' started by chiefsilverback, Aug 7, 2016.

  1. chiefsilverback macrumors 6502

    Joined:
    Jul 25, 2011
    #1
    Sat down to watch an iTunes rented movie last night on my ATV 4 and had horrible delay between picture and audio. My setup is ATV into LG TV via HDMI then audio from TV optical out to brand new Vizio sounder.

    My guess is that the culprit is the TV>soundbar, because the video is ahead of the audio so I think by the time the TV has processed the HDMI signal, send the audio to optical out and then the soundbar has done its bit the corresponding frames have already appeared on the screen.

    My TV has no audio-sync options that I can find, so I'm wondering if my best option isn't to get an HDMI audio-extractor? If I'm going that route I could potentially find myself with audio leading video, so does anyone know if you can get an extractor with sync adjustment?
     
  2. JeffPerrin macrumors regular

    JeffPerrin

    Joined:
    Jul 21, 2014
    #2
    Best would be to go from ATV right into to sound bar, if possible.

    I experienced a similar issue when trying to go from ATV4 to my LG and then to my receiver (via optical). Apple told me some TVs will have this problem. In the end, I had to go from ATV HDMI straight to receiver to eliminate the sync issue (the receiver then passes video to TV via HDMI output). Hopefully your sound bar has an HDMI input?

    Weird as I never had this issue with the ATV 2 or 3 though. More side-effects of the ATV4 on-board audio DSP, I suppose...
     
  3. chiefsilverback thread starter macrumors 6502

    Joined:
    Jul 25, 2011
    #3
    Alas no HDMI on the sound bar audio inputs only, hence the thinking about an HDMI audio extractor...
     
  4. JeffPerrin macrumors regular

    JeffPerrin

    Joined:
    Jul 21, 2014
    #4
    Hmm. Never tried one of those. Can't say if it would solve the issue for sure since there are two independent conversion processes happening (no true sync - but might just be close enough). I'd get the extractor from some place that would let you return it if it didn't work out (i.e. Best Buy).
     
  5. chiefsilverback thread starter macrumors 6502

    Joined:
    Jul 25, 2011
    #5
    They start at $30 from Amazon so even if it get's closer than it is now it will be worth it. My fear is that it might reverse the issue and put the audio ahead of the video which is why I want to see if there's a model that would then give some adjustment...
     
  6. tjwilliams25 macrumors 6502

    Joined:
    Aug 10, 2014
    Location:
    Montana
    #6
    I would suggest trying out the audio extractor. You shouldn't be seeing delays as the stream isn't being decoded in the extractor, which is why you're having an issue with your TV. It just strips the audio and sends it via whichever output (I would suggest optical if your soundbar supports it). That being said, be careful what kind of device you buy. There are a lot of knockoff products that are cables and boxes that don't actually do anything, especially through third party sellers on Amazon. Some that I've seen look like an HDMI cable on one end and optical on the other. Those don't work at all. The process requires power to work, so make sure you get a powered box.
     
  7. chiefsilverback thread starter macrumors 6502

    Joined:
    Jul 25, 2011
    #7
    I ordered one of these: https://www.amazon.com/gp/product/B00LKF6CPG/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

    I don't need 4K or ARC today, but I wanted to make sure CEC works so for an extra $3 it seemed to make sense! Should be here on Wednesday so I'll let you know how it works...
     
  8. chiefsilverback thread starter macrumors 6502

    Joined:
    Jul 25, 2011
    #8
    I watched something via the PBS app last night and the audio delay was pretty much non-existent. One key difference is that it was stereo only, no Dolby Digital!?!?
     
  9. tjwilliams25 macrumors 6502

    Joined:
    Aug 10, 2014
    Location:
    Montana
    #9
    Then it's definitely however your TV is decoding the Dolby stream and then passing it to your sound bar. The stereo stream is probably in LPCM, so it's not being decoded. That extractor looks like it should work great. Let us know!
     
  10. chiefsilverback thread starter macrumors 6502

    Joined:
    Jul 25, 2011
    #10
    Got my box, plugged it in and it appears to have solved the problem. It also means that I can AirPlay to the AppleTV now and not have to have the TV turned on, so it's a double bonus!
     
  11. cynics macrumors G4

    Joined:
    Jan 8, 2012
    #11
    Make sure you restart you AppleTV before going much further (hold menu button + play/pause until the LED flash rapidly). It might not do anything but it's worth a shot.

    I get audio syncing issues every so often and need to restart the ATV to fix it. In my case it comes and goes...the video will freeze frame and it will be fine for a while then start again a few minutes later.
     

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