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Old 04-27-2004, 10:25 PM
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dr sound dr sound is offline
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Default Lip Sync and Plasma Monitors

Here is a neat little article about lip sync issues with Plasma monitors:
http://www.eetimes.com/showArticle.j...cleID=18901792

So 100 ms delay is OK ?
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Old 04-27-2004, 10:59 PM
CPettigrew CPettigrew is offline
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Default Re: Lip Sync and Plasma Monitors

Had that problem scoring an animated feature at Abbey Road; watching on plasma monitors, scratching our heads a lot and wondering why sync points looked loosey-goosey. Once we were informed of the offset/latency, we switched back to the old-timey TV monitors in the corners. Sheesh!

Craig
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Old 04-27-2004, 11:22 PM
amiller amiller is offline
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Default Re: Lip Sync and Plasma Monitors

Interesting article. I wonder if it's possible to "retro fit" any of the current sets with the PNX8550 chip, or does it have to be built into the set? Kind of a bummer to get confirmation to learn that LCDs suffer the same deal as well. This just after I finally found a 40" flat panel LCD at NAB...
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Old 04-28-2004, 07:40 AM
trakbytes trakbytes is offline
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Default Re: Lip Sync and Plasma Monitors

From reading the article, it looks like the chip is only going to help with sound coming from the TV itself. Not much help if your sound is coming from from another source (such as your Pro Tools monitor outs for example).

Been experiencing this plasma delay first hand the last couple of weeks, since our trusty 52" TV's have been replaced with 46" plasma displays. After doing a few D5 laybacks that came back out of synch, engineering has programmed a 53ms delay into the room EQ. This seems to have tamed the problem, and seems transparent, although I object to the idea of putting a delay in the monitor path out of principal.

Now, a question I have, does the plasma display delay video on the computer input? When I scrub picture in Pro Tools (video out through Radeon 9800 to both an LCD monitor and the plasma computer input), it seems the LCD and plasma displays change on the frame at exactly the same time. It would seem if there was a delay in the plasma, I would perceive some delay in scrubbing between the two monitors. Maybe it's not perceptable at scrub speed. Anybody know if the computer input would exhibit the same video delay?

The big plasma display sure looks good though, expecially with D5 component source.

rcm
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Old 04-29-2004, 06:57 PM
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Default Re: Lip Sync and Plasma Monitors

I had a Panasonic flat panel in a studio. The engineer wanted it because it looked cool, had appeal, etc. There was a 2 frame latency. A client threatened to never come back unless we fixed it.

We now have a 36" Sony CRT in the room. Enough said.
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Old 04-29-2004, 09:57 PM
Christian Dolan Christian Dolan is offline
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Default Re: Lip Sync and Plasma Monitors

Quote:
Now, a question I have, does the plasma display delay video on the computer input?
I don't think so. I believe that the latency is caused by the processing involved. When you send interlaced NTSC video to a high-res display, two things have to happen: One, it needs to be converted to progressive scan; Two, it needs to be scaled to the native resolution of the display. The computer monitor output doesn't need to be scaled up, so it can be displayed in real time.
Hope this helps,
Christian
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Old 04-30-2004, 02:40 AM
AG AG is offline
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Default Re: Lip Sync and Plasma Monitors

Yikes, that explains a lot. On a pilot at Sony recently (where they have, what else, Sony plasmas), we did final playback for the network and ten minutes in the powers said to stop, because it looked out of sync. After taking a day replacing all the ADR with production, we spent another day trying to figure out why it still looked the same.
_Scott
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Old 04-30-2004, 05:33 AM
DAPG DAPG is offline
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Default Re: Lip Sync and Plasma Monitors

This sync problem has not been well known. I am glad it is coming to light. In our main mixing suite we have a 56" DLP monitor. It has about 53-60ms latency. Since we mix in the box, all we do is insert a 60ms delay on the master output of PT. It works great (also works in multichannel mixes)....however.....you have to remember to disable the delay before you layback.

This latency problem will probably be around for a while, so please share your knowledge about this issue with picture editors and clients who work with non-CRT (digital) monitors (Plasma, LCD, DLP) so that everyone is aware that an audio delay is absolutely necessary for tight sync. Rane and Sony make frame delays than can be used for these applications (where a delay needs to be inserted in the audio monitor path) and for those mixing in PT you can use the method described above.
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Old 04-30-2004, 06:09 AM
Richard Fairbanks Richard Fairbanks is offline
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Default Re: Lip Sync and Plasma Monitors

I have to vent on you all. This is hardly new information. Yes, it is shocking that a manufacturer can fool itself into believing that anything less than 100ms (2.5 to 3 frames) is not perceptable. Of course all of us in audio know that is wrong, since we regularly fret over 1/4 and 1/2 frame nudges. Or rather, all of us in audio SHOULD know that. Which brings me to my point. We have known for years that all digital displays have latency, there have been many dozens of posts about it on this BBS, many in this very forum. How on earth can you put a big new display in front of you and not check for latency? That is like putting up new speakers without checking to see what they sound like before clients walk in for the first mix. If some of the major facilities did this then I can only laugh at them, it shows the level of incompetence and herd mentality which is rampant. It shows laziness.

Get in gear, people! The fact that this is a revelation to some who spend every working day putting sound in sync to picture is simply embarrassing!

Put a delay in the monitor path and get over it! Or use a CRT. Run your own tests to figure out how much the delay should be, or look it up on the manufacturer's website. If you only work in the box with quicktime picture then add a few quarter frames more to your movie sync offset. Whatever it takes.

The powers stopped playback to point out a sync problem? Come on! The problem was obvious before that playback ever happened and should have been noticed.
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Old 04-30-2004, 06:22 AM
CPettigrew CPettigrew is offline
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Default Re: Lip Sync and Plasma Monitors

Some of us are poor folk in the hinterlands who have used nothing but CRTs and have been in large, famous studios where THEY have used nothing but CRTs for video playback. So when these new displays are thrust at us without intro and preamble our first reaction isn't, "Hey, I'm getting with the program here and telling you exactly how to compensate," it's "Hey, how come everything looks slightly out of sync." Sorry we're so stupid. But now we've been dutifully informed, so we won't make that mistake again.

Craig

P.S. They had installed this beautiful plasma monitor in Studio 1 at Abbey Road, recorded 65 orchestral sessions for "Bored of the Rings" (and that's just for the third installment) but it took a little Disney animated movie to get them to flip back to the CRTs.
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