Blackmagic Design Forum
Decklink 4k Sync with Plasma 3D displays.
Decklink 4k Sync with Plasma 3D displays.
by Charlie Carr on Oct 10, 2014 at 3:56:44 pm

I'm having trouble with sound sync. Long story short. I believe it's because i'm using Panasonic 3D Plasmas. Has anyone run into this, i've tried searching. And now details to follow.

I have two Panasonic Plasmas, TC-58AX800U and TC-P50T60, both are 3D capable. I'm connected to them both with Mac's running 10.8.5 with Decklink 4k Extreme cards with 10.2.1 as the drivers connecting to the displays via HDMI. The audio is running out of the XLR out from the DL card to a small mackie mixer then out to speakers. I'm getting the same issue through FCP 7 and Premiere CS6. The exact same delay. No matter what i set the offset to in FCP the display is always a frame or two behind the audio from the mixer. So i shut the board off and listen to the audio from the internal display speakers. Looks in sync. So i ran audio from the back of the tv to the board, still get the delay.

I don't believe the problem to be the mixer, i'm using the same ones on other setups, and it's analogue, so really no "processing" is happening. Those other setups are using Panasonic Plasmas, but not 3D. My only thought is that the TVs are some how processing or computing the image that's input into it then displaying it. The only thing that doesn't support that claim is that i'm getting the delay when i run from the tv's digital optical out into the board, but i'm also using a digital optical out to analog rca converter to get into the board.

Any advice or suggestions would be great. One thing to note is I can't hook into the displays via component. I thought maybe if all the signals were analog there might not be an issue. We just renovated our office and HDMI was installed into the walls. As well as the TC-58AX800U is 4K and the only way to display 4k is via HDMI.

Thanks for your time.

Re: Decklink 4k Sync with Plasma 3D displays.
by Chad Pearson on Oct 10, 2014 at 7:18:34 pm

It is normal for the audio to be out of sync with the video when splitting the audio to something other than the TV you are playing back on. That's because virtually ALL TV's do internal processing on the image which causes video delay. However, I'm baffled why the audio pass-through from the TV isn't delayed to compensate for that. My only suggestion would be to turn off as much processing in the TV as possible. Usually this means switching the picture mode to "Game" (gamers hate lag), setting the scaling / underscan to none (or dot-by-dot or similar) and turning off all the motion compensation, dynamic contrast, 120/240hz (soap opera effect) BS, etc. Just turn it all off.