Using LCD TV for Post production

[laddie.music2]

Hi, I have a 52inch Phillips LCD tv that is hooked up Via a black magic card on my PC for post production work.

Using Nuendo 4.3 and Cubase 5,

The problem i'm having is, the screen is slower than nuendo and cubase...
I know I can change the 'black magic' output which would effectively sync the LCD screen up with my session perfectly.

My problem is, how can I perfectly accurately test how slow the LCD TV is?

My friend said we could take a photo of the transport and and LCD TV in a photo and compare time codes.... and add how ever many frames to the Black Magic latency for nuendo.

Any thoughts and help is very appreciated...

are there any 'scientific devices' that can help?, i'd really rather not use the photo or 'eye it'

thanks
Laddie.

[TVPostSound]

SYNCHECK.COM

[Big Andy]

What kind of computer are you running?

In the case of my own TV at my home studio, I need to make my Macs main video output 1280x800 in order for my 48" LCD TV to play back at 1920x1080 with out lag. Your best bet is to call your TV manufacturer and ask them what your computers graphics card resolution output should be set to. I'm willing to bet this is your problem, not that the TV is to slow.

[Uncle Bob]

I've never used Nuendo and haven't touched Cubase in years, but Pro Tools has a delay compensation. For my own system it's 22 quarter frames (5.5 frames).

[BIGBANGBUZZ]

I run an Mbox 2 with Dv Toolkit2, I have a Samsung LCD, which has 2ms refresh time.

I have the offset at negative 4 1/4 frames

[emf1138]

+1 Syncheck

[laddie.music2]

Awesome, awesome, thanks heaps guys

Syncheck looks great, and seems perfect for what i need.

Nuendo and Cuabse have the offset for the video so syncheck will be perfect.

[Fabi]

Unfortunately the panasonic I sometimes work on varys its delay with the brightness of the picture up to estimated +/- 1frame. And I don´t mean the brightness setting. Dark scenes have less delay - bright ones more.
Its a pain in the -->

[ErikG]

Yup Definetly one issue to be aware of. And hard to realize as well as it cant be detected with sync check. I have a Philips that does this, to be replaced asap.

[philper]

Is this changeability of sync a "feature or a bug"? In other words, is there a manufacturer-official name for this that one could spot in spec sheets? From observation I've suspected this variable sync thing was true for a long time but have never heard it mentioned on a forum before. Is this problem common in all flat screen monitors, just some, just cheaper ones, just Panasonic and Philips or what?

Philip Perkins

[ggegan]

Originally Posted by ErikG

Yup Definetly one issue to be aware of. And hard to realize as well as it cant be detected with sync check. I have a Philips that does this, to be replaced asap.

How did you determine that the latency was changing? Was it by observation, or was there information about in in the LCD specs?

[laddie.music2]

wow, brightness can effect latency?,

I don't see how that would change synchecks ability to detect the latency differences???

What a nightmare...

Anyone got one of the new LED ultra thin screens out?, the ones that are 1 inch thick, any experience, are they faster etc?

[ErikG]

Sync check cant distinguish anything but dark interrupted by bright flash or a ledar number (2pop us, 3pop Europe) so therefore there's no way to check sync in a pic sequence as such.

The variable sync caused by light/color changes can sometimes be seen during pans when a light part of the pic will offset visually on screen.

We have come to this conclusion by using the exact same setup with different screens. Both screens are first checked for correct alignment with sync check and the sync pop. Running the picture you can visually see the non sync parts on one screen and not the other.

When time allows I'll try some more tests as I'm not 100% certain why and when this happens.

[ggegan]

Originally Posted by ErikG

Sync check cant distinguish anything but dark interrupted by bright flash or a ledar number (2pop us, 3pop Europe) so therefore there's no way to check sync in a pic sequence as such.

The variable sync caused by light/color changes can sometimes be seen during pans when a light part of the pic will offset visually on screen.

We have come to this conclusion by using the exact same setup with different screens. Both screens are first checked for correct alignment with sync check and the sync pop. Running the picture you can visually see the non sync parts on one screen and not the other.

When time allows I'll try some more tests as I'm not 100% certain why and when this happens.

How many msec of variation are you talking about? Is it just during the transition or does it stay constant until the brightness changes again?

[philper]

So when you see this, does the film "pop" out of sync and then fall back in (or closer) when the scene brightness changes? Or does it stay out? Or is the change more gradual? Anyone else see this?

Philip Perkins

[ErikG]

Gary: msecs? I dont know since I cant measure it. My guess is around 1.5 frames at worst.

No it wont "pop" out of sync. But the sync will get "gooey" it will look and feel off in various sequenses and not in another, the only thing that differs between these pic sequences are light and color levels. Thats why i strongly believe this is the problem.
Otherwise I would get the same problem on the same program material in identical or swapped equipment, and I simply dont...
Only variable left seems to be the screen.

And just to clarify, the problem DOES go away if I swap the screen to another and sync it all up.
So my guess is that its not officially out of sync but only feels like it. As soon as you double check a plosive ound or some other distinctive sound (by scrubbing) that have relevance on screen its in perfect sync as is the sync pop (confirmed with SyncheckII).

Unfortunately I have pretty exact dimension requirements for this screen so I have not found a suitable alternative yet, besides I would very much like to be 100% certain wtf is going on and if this is a problem that might exist on lots of screens...

Pretty scary shit. as it makes you doubt what you see and hear...

[laddie.music2]

Originally Posted by ErikG

Gary: msecs? I dont know since I cant measure it. My guess is around 1.5 frames at worst.

No it wont "pop" out of sync. But the sync will get "gooey" it will look and feel off in various sequenses and not in another, the only thing that differs between these pic sequences are light and color levels. Thats why i strongly believe this is the problem.
Otherwise I would get the same problem on the same program material in identical or swapped equipment, and I simply dont...
Only variable left seems to be the screen.

And just to clarify, the problem DOES go away if I swap the screen to another and sync it all up.
So my guess is that its not officially out of sync but only feels like it. As soon as you double check a plosive ound or some other distinctive sound (by scrubbing) that have relevance on screen its in perfect sync as is the sync pop.

Unfortunately I have pretty exact dimension requirements for this screen so I have not found a suitable alternative yet, besides I would very much like to be 100% certain wtf is going on and if this is a problem that might exist on lots of screens...

Pretty scary shit. as it makes you doubt what you see and hear...

tell me about it....
i'd be interested to see how these new slimline LED screens perform regarding latency etc...

any experence?

[ggegan]

Thanks Erik,

This is a somewhat disconcerting issue. I have not noticed the problem on my 40" Samsung LCD, but then the low quality of the Quicktime movies I generally get from the picture department often makes it very difficult to determine absolute sync by eye, especially when the security watermark is right in the center of the screen.

For feature films the whole sync issue is iffy anyway. The distance from the screen to the mixing position in a large dub stage can result in as much as 3/4 frame delay in the sound. A dozen or so rows of seats in a theater would constitute somewhere around a frame of delay, so much of the audience in a large theater is hearing the audio anywhere from one to two frames out of sync. I noticed this even as a small child because my Mom was late to everything, so we always ended up sitting in the very back of the balcony of the large movie palaces they had back then, which means the sound was probably close to 3 frames delayed. Everything looked like a Kung Fu movie.

This is no excuse not to get the sync correct, although ever since the advent of digital picture and sound editing, I have never been absolutely confident of dialog sync anway.

[jimlongo]

Originally Posted by ggegan

This is no excuse not to get the sync correct, although ever since the advent of digital picture and sound editing, I have never been absolutely confident of dialog sync anway.

Amen brother . . . even coming directly off the camera.

[philper]

Originally Posted by jimlongo

Amen brother . . . even coming directly off the camera.

Especially digital cameras.

To the OP: did you look at any of these scenes on a CRT monitor for comparison? Are you sure that this isn't a QT processing issue in the playback equipment?

Philip Perkins

[Jfriah]

I concur with Gary's stories about theatre position sync.

let me also add

cough cough HDTV broadcast cough


Jeff

[eoats]

I know of facilities that wrestling with such issues. The flavor of QT (or other pictures devices) with what computer & things makes for a complex soup.

I find with ProTools and running a .dv type picture file thru a Canopus box is different sync than with a QT file playing out on a second monitor....

Sometimes I miss my sync bloc and tape splicer

[Kuba_Pietrzak]

That's why I still have tube crt tv next to 42-inch LCD.
I can be sure, that if something is in sync on that old device - it will be in sync on everything.

Kuba

[Fabi]

Originally Posted by Kuba_Pietrzak

That's why I still have tube crt tv next to 42-inch LCD.
I can be sure, that if something is in sync on that old device - it will be in sync on everything.

Kuba

Exactly what I do and I can highly encourage everyone to do this.

Its also fun to watch both at cuts in the picture and see how much they differ. Kind of shocking

Another opinions is though that most consumers at home (Broadcast Business only) will have LCDs soon or even already. So the will have to live with the same difficulty. You could argue that if its sync enough for you on such a screen it will be for the customer.
I personally dislike that idea though and see it as a decrease of quality

Just my 2cents

[Kuba_Pietrzak]

As a mixer, I do not take so much care about the picture quality - I let video guys to fight this battle, however my problems is, that some kind of, I would say, "reality tv sound quality factor" is becoming a norm in some fields and is described by people as "natural"...

Kuba

[ggegan]

Until recently I had been setting the video offset of my personal PT8/ICON system by eye and decided that 6 quarter frames seemed to look pretty good for Quicktime DV. I finally broke down and bought a Syncheck and checked it. It turns out the actual offset is slightly more than 5 quarter frames. Since 1/4 frame is such a negligible adjustment, I had a little buyer's remorse, thinking maybe I should have used the money to buy a new bicycle for my wife, but I decided that the peace of mind was worth it. We have too many bicycles anyway and I can hardly squeeze into the garage as it is.

[ErikG]

A bike, in LA? What for :-)?

As much as I enjoyed staying in LA 2 yrs ago, riding a bike did NOT seem lika a normal means of transport...

Neither did busses or subway for "most people"...

[ggegan]

Originally Posted by ErikG

A bike, in LA? What for :-)?

As much as I enjoyed staying in LA 2 yrs ago, riding a bike did NOT seem lika a normal means of transport...

Neither did busses or subway for "most people"...

I live in Culver City which is a small town in the middle of a large metropolis. We ride bikes and actually even walk to stores, restaurants, bars, the beach, friends houses etc. I can even ride my bike to some of the studios I work at.

[ErikG]

You mean that there actually exists people in LA that don't take the car around the corner? Just kidding.
LA is a strange place indeed. Huge but still not really feeling like a big city (unless you go "down town")

[Jfriah]

Also, one should always try pulling video onto your main work/mix/edit screen if that's what you're working in, and watch a pass there.

Just thought I'd throw that out there.

And re: bikes---I used to really enjoy my 4km bike ride to work in Vancouver. It was about 4 minutes TO work about about 20-25 FROM work. Nice big ol' hilllllll to conquer, usually in the drizzle, at the end of a long hard day. Good for getting frustrations out, hitting that hill.

Jeff