Lip-sync issues with W755c

[timodell]

I know this is an ongong problem, but I just wanted to specify the particularly acute issue with some aps. MUBI and WUAKI both seem to have the sound that lags the picture using both internal and Optical out - this is not resolved by power-off re-set. Because the sound lags, it cannot be compensated for by an external AV amp as many of the other lip-sync issues can (eg. Netflix).

More generally, many sources (especially SKY) have variable lags when watched through HDMI which requires frequent re-setting of the audio delay either on the set-top box or the amp. Often a base-line lag can be re-established by a power-off reset, but then drifts shorter or longer over time.

[NickJoh]

Actually a variable audio delay "can" be used to correct lip-sync error when the incoming signal already has delayed audio in "most" cases.  I do it quite often with my Felston DD740.  The trick is to use the inherent video delay of your TV.  Almost all modern flat screen TV's (non-CRT) delay the video between 50 and 100 ms so to gain access to that video delay you must make sure all other audio delay settings are turned OFF or set to zero and let your variable audio delay (whether an AV receiver's delay or an external lip-sync correction device like the Alchemy2, Felston or Primare Delay Box) provide "all" the delay to correct lip-sync. That will give you a variable video delay  - basically a negative audio delay - equal to your TV's video delay.

Example: My TV has about 80 ms vdeo delay so when my Felston DD740 is set to 80 ms audio delay a signal that arrived in sync (almost never happens) would have perfect lip-sync. My settings are usually in the 110 to 140 ms range indicating those signals have varying lip-sync error between 30 to 60 ms of delayed video.

In the rare cases where audio is already delayed in the arriving signal as you are talking about I simply press the minus button on my DD740 and go below 80 ms until lip-sync is perfcet again.  If I find perfect sync at 10 ms that means that signal had audio already delayed 70 ms and I was able to use 70 ms of my TV's 80 ms video delay to cancel it.  Of coures if the arriving signal has more audio delay than the total video delay of your TV (80 ms on this TV but my previous TV had 100 ms video delay) you won't be able to completely cancel it but this should at least help.

If you are using HDMI be sure to turn off the auto lip-sync corection feature since all that feature does is add a fixed audio delay based on what your TV's video delay is and that will deny access to this negative adjustment range.

As long as you turn OFF all other audio delays (in your TV, STB, DVD, BluRay, etc.) this should work with the audio delay provided by an AV receiver but they often adjust in larger increments so you probably won't feel lip-sync is ever quite perfect.  All the external lip-sync correction devices I mentioned adjust in 1 ms increments using a remote handset and they don't upset the talking head targets with menus so they will allow achieving perfect sync.  Mine can actually adjust in 1/3 ms steps but I never use fine mode