Originally Posted by SlackDad
I did some internet research on this issue and now understand that this is certainly a widespread problem and can be caused in part by the broadcaster and/or carrier but is a 'feature' of LCD TVs due to the increased processing it takes to create the image relative to sound. And is more likely to get worse with HD due to the increase in image processing.
There are always delays to the video steam associated with scaling, which do not affect the audio stream. Professional quality video scalers include an adjustable delay-line for the audio, so that the two outputs are back in sync. Delay-lines are rarely seen in domestic quality kit.
With the TVdrive and plasma or LCD screens, there are at least two
scaling operations going on: once in the TVdrive to upscale for the HDMI output, and again in the TV itself to re-scale to the native pixel resolution. The combined delays of these two scaling operations might be apparent to the alert viewer. Perhaps you should try your TV set on sources other than the TVdrive to see if you notice the effect in the TV on its own.
It has been previously reported that sometimes the TVdrive exhibits severe lip-sync problems, and that these were reported as cured simply by changing channel and back again. I can't vouch for either of those reports.