Plasma monitor : Audio to Video delay... BEWARE !

[Aquarius]

Hi guys !

Following the thread in the Post forum, I share this with you :

My crt TV died a month ago and I decided to bring a brand new shiny Plasma monitor in the studio to...impress my clients and make the room look great.....oh my God !!!!
My first job with the new screen was a series of short TV comics. I noticed immediately some strange issues with lipsync - looking at the movie window in PT versus the plasma - , alas the director was in the room too, but I managed to shut it off before he realized it !!!
After the day, I brought in a spare crt to compare the 2 images and It was perfectly in sync on the regular TV , but about 17 to 20 quarter frames delay ... :crazy!
I bought the plasma screen (LG) from a official Sony reseller and when I told him I had these strange issues, he replied I was the 1st customer to report that !
I then called a friend of mine who's a well respected movie mixer and he said he was not aware of it but noticed it could make sense because of the Dsp induced delay of the video processing;
He said people are using plasma to cut films on Avid and no one has complained so far...
So I called back the Sony guys and said It was unusable: he then came back with video projectors (LCD matrix) and noticed the same behaviour.
I was very confused about what to do and tried to compensate the offset using the movie offset in ProTools and didnt ask for my money back !
It's been since a nightmare !
I had to share this with you...be smart before putting your money on a new monitor.

Best regards,

Peace

[surroundguy]

What brand plasma was it? LG?

[Aquarius]

Yes, the brand is LG ;
They also make the screen for Sony, so...

[KingFish]

Hmm - this is a plasma TV ?? you'd think that if it had video latency due to DSP processing of the digital video signal, that it would introduce the same latency to it's audio signal path so that the audio was in perfect visual sync with the video, otherwise simply playing a DVD through the TV would yeild out of sync results.

This could explain why someone editing film on a Avid rig may NOT experience any problems, as long as they were monitoring their audio through the plasma screen's built in audio.

I'd be curious to see, if you double monitored audio, split a signal from your console / studio / PT rig, and simultaniously monitor audio through the plasma screen, and your studio monitors.... is there latency there ???

Just curious.

[Richard Barrie]

This is not just an issue with Plasma screens, but is also the case with most LCD screens as well. To test this play back video with burnt in code, preferably showing fields as well as frames. Create a 'video wall' with your selection of monitors including a standard CRT monitor. Frame your wall in a shot with a video camera and then record onto something like a Digibeta - making sure that you are using the same video reference for all the machines in the described system.

You can then jog through the tape you have just recorded and watch the burnt in code on each of the displays and assuming your CRT monitor has no delay you can then see the delays for each of your other type of monitors.

I have seen delays of up to four fields (two frames).

The only LCD display that I have found with no delay at all is the no longer available, original Apple 15" Studio Display. When we discovered this we bought up as many of these that we could find.

As for audio compensation, I have yet to see this implimented, but might be done in more up to date kit than I have available. Some 'home theatre' amplifiers have the capability to compensate for the delay.

[SHIRK]

I've noticed some video delay in playback on my plasma screen as well. I'm running a Panasonic 42". I've noticed this problem only after I upgraded to HD service (new Pioneer Converter box with DVI and Component Video out). I'm in Manhattan using the Time Warner Digital Cable (HD package) The image is stunning (especially the Discovery HD Theater) However, I do notice a little drift in the sync. It kind of comes and goes. It is obvioous that there is extra processing going on to properly scale thesse images. Not sure if it is in the converter box supplied by TWC or the Plasma monitor itself. I've got a friend that does installs of high end home theaters and the like around Manahattan and he says this is a problem that the cable companies are trying to deal with. He's in favor of some kind of user definable sync offset / buffer to alleviate the problem.

When I've been working to picture with ProTools, I've been offsetting the image by approx 24 quater frames and getting good results. I'm just using the canopus DVC100 firewire output. Nothing amazing but it works for my needs.

[Aquarius]

Hi Shirk !

I'm about to buy a Canopus ADVC-100 to use with my LG plasma .
I'm curious about your offset : I'm still using a Miro DC 30+ (alfanet driver) and found +17 quarter frames (PT Movie offset) was ok with lipsync.
I know Digi recommends +18 quarter frames (Pal) for the Canopus : so the LG latency would be 4 quarter frames ?
Aniway, that does only apply to the plasma screen, not for crt's so I will have to decide what picture to show to my clients in the studio...
I just hope they won't ask the 2 monitors at the same time !!!

Peace