JVC SR-MV45 - delay on A/V passthrough

[Mitch Cohen]

Hi,

I have a new JVC SR-MV45 (DVD/VHS deck) in a large meeting room setting. Cameras and mics go through mixers to the deck, then out the deck to a large TV (with audio) near the back of the room.

The deck introduces a noticeable and bothersome delay to both the audio and video signals passing through. It's so much as to be disruptive, probably about 0.25 seconds. The audio and video remain in sync, just delayed.

If I bypass the deck (by using a coupler to bridge the in and out cables) the delay completely goes away. So it's definitely the deck.

We actually have three MV45's; I've swapped them out and all have the same issue.

Any idea if this is "normal" with this deck, and is there a way to eliminate it short of splitting the signals? I prefer to pass through as it confirms the deck is set to the correct input (everything is also being recorded).

Thanks!

[orsetto]

It's normal. The deck does not really have a pass-through mode: it is ALWAYS trying to encode whatever appears at its inputs and then feed them to its outputs, but this imposes a slight delay from "real time". This applies to both the analog and DV inputs: many people assume the DV input on DVD recorders is digital-to-digital but it usually isn't, the decks perform an on the fly internal DV-to-analog-to-MPEG2 conversion. Because of the a/v "echo" issue, these units shouldn't be part of a "live" equipment chain, they are better placed at the very end and monitored separately.

[Mitch Cohen]

Thank you. While not the answer I was hoping for, it's a viable explanation. Much appreciated.

We'll do a little rewiring to put these at the end of the chain.