Originally Posted by xenokira
Just posting some thoughts and maybe some of you have already figured this out...but I think, at least for me, the lip sync issues only seem to only occur while watching a video source (via HDMI) with Dolby Digital audio. In my set up, audio is sent from the TV via optical to my receiver (with Dolby Digital enabled in the TV's audio options). The lip sync issue intermittently happens on both my PS3 and HTPC.
Resetting the connection seems to temporarily resolve the issue--on my HTPC running Windows Media Center, I can usually just pause the video playback and audio is re-sync'd since the audio mode is reset while playback is paused. On the PS3, it's not quite as easy, but resetting the TV audio option from and back to Dolby Digital resolves the issue (again, temporarily).
I'm guessing the TV's audio processing just can't keep up with passing on the Dolby Digital audio from HDMI to optical--then just hiccups at some point causing the sync issues. Assuming no fix from Vizio ever comes along, I'm looking at three options:
1) Continue dealing with the lip-sync issue
2) Disable forwarding of Dolby Digital audio and lose my 5.1 audio as a result or
3) Replace my receiver to one with with a built-in HDMI switch and remove the TV from the audio equation entirely.
Disclaimer: I should say that I really don't think it's my audio system--I have a pair of Astro A40's with mixamp that have had the problem occur when connected to the TV in place of the audio system.
My long term plan is #3. In the short term, probably #1. I don't mind dealing with it personally, but it's actually quite embarrassing when guests are over for a movie or TV premieres / finales--and honestly, I think it looks bad on Vizio too.
Hmm... I have mine connected with optical output to my receiver, and have never noticed any lip sync problems. From a signal processing standpoint, forwarding the Dolby Digital audio stream from the HDMI port to the optical port is a fairly trivial task. There is no transcoding of the signal necessary, it just forwards the Dolby bitstream from the input transport stream in the HDMI signal to the optical port.
I have a TiVo Premier Q cable DVR box. I also have an XBMC HTPC, but it has an older video card without embedded HDMI audio, so I'm using the stereo output on the HTPC to the TV set, and in that configuration the TV actually encodes the analog stereo audio to PCM digital and forwards it out the optical port. THIS
takes more processing power than forwarding the Dolby Digital signal, and I never see this audio out of sync either.
I have no answer to offer, however, regarding lip sync issues. If you switch the TV output to PCM mode, you will lose the 5.1.... but does it fix your lip sync problem, I wonder?