HD System

[Bob Zelin]

We are putting together our first Graphics HD Workstation (we have several AVid HD systems) using the Decklink Multibridge. The things we are discussing with our engineering crew is sync, and monitoring. We need “Tri-Level Sync” to do HD, but we also want to switch between HD and SD (one of the benefits of the multibridge or extreme HD). It’s been explained that we need 2 different sync sources to switch back and forth.

1) What is tri-level sync, and how does it differ from standard sync?

REPLY
Tri Level sync is a simple pulse that for most peoples uses, operate at varying frame rates – like 23.98 or 59.94 (which is the normal frame rate). Standard sync (in the 80’s, 90’s and this century) is also known as composite black, which operates at 29.97 in the US. As far as you are concerned, standard sync (29.97) is the same as 59.94 for doing 720p and 1080i projects at normal frame rates.

2- Why do we need to switch sync to go back and forth, and with that being the case how do you set up the separate sync sources with the decklink products mentioned.

REPLY – If your system is doing a 23.98 project, your VTR and your Blackmagic card cannot “sync” or genlock to a framerate that is running at 29.97. So, if you are operating at 23.98, you will need a sync gen (tri level sync gen) that runs at 23.98. There are many companies that make tri level sync gens, but one of the most popular is the Evertz 7750, which is a card that goes into a frame that Evertz makes. Ensemble, Astro Systems, NVision, Tektronix, Leitch, Ensemble Designs, Sigma Electronics and others make tri level sync generators as well. They start at about $3000 (which is a crime).

HOWEVER – you do not need to switch back and forth if you are doing a project for TV. If you let your VTR do a 2:3 pulldown (like the Sony J-H3 VTR or the Pansonic AJ-HD1200A, which both do 2:3 pulldown), the 23.98 video signal will be converted to 59.94. At this frame rate, everything runs standard, and you can continue to use your cheap Horita Black Generator to sync everything together. I see little reason to operate at 23.98 while editing unless you are finishing for a feature film, which will release at 24 fps.

The easiest way to switch back and forth is to bring up the genlock (or Ref Video) inputs to a patch bay, and patch in your tri level sync, or standard black into the reference inputs. The AVID Adrenaline HD has a seperate input for HD sync in (tri level sync).

Finally, The multibride has a DVI Dual link connection to allow HD monitoring on a LCD Screen. Is anyone using this, and what are you feelings about the LCD Monitoring vs traditional (and much more expensive) CRT?

REPLY –
The Multibridge DVI output is WONDERFUL. ALL of Sony and Panasonics new monitors are LCD monitors, and not CRT monitors. If you look at the new Sony Luma monitors (LDM-232, for example), or the Panasonic BT-LH2600W, these are LCD monitors, and they work great. But Blackmagic gives you a DVI output, so instead of spending a lot of money for these, you can get an Apple Cinema display, or Dell 2407FPW 24″ LCD monitor, and see the same picture, at excellent resolution. Almost NO ONE is willing to spend $35,000 for a Sony HD CRT monitor, and most people have given up on using CRT monitors for HD monitoring, since no client will
ever own a CRT HD monitor. A hi end alternative on LCD is the eCinema 23″ LCD monitor, which is about $15,000 – I have no opinion on this product.

If you get the Multibridge Extreme, it can drive a 30″ Apple Cinema display, which will make you very happy for editing.

JUST FOR THE RECORD – the AVID DS and AVID Nitris require tri level sync for HD editing, however the AVID Adrenaline HD DOES NOT require tri level sync when operating at 59.95 frame rates – either at 720p or 1080i. A cheapo black generator will work just fine. Just remember to let your VTR do the 2:3 pulldown to 59.94 if your source tapes are shot at 23.98.

Bob Zelin

[Michael Goldberg]

Bob thanks for the reply. This helps alot.

Mike

[Miles Blow]

Hi
One think we noticed on the dell 24″(halve the price of the apple 23″) is that bright images look the most natural. Dark images look a bit grey because of the way the lcd always looks a bit “iluminted”. When you first turn it on it doesnt look totally black…like it does on a crt. Thats my 2cents worth. Other than that it looks totally amazing! We love it. Also on the dell if you run s-video or component into it, it looks pretty bad….. stick with dvi. If you go s-video in through the multibridge it looks better. But hd on it is epic.

Miles

[Andrew Mcleod]

Tri-Sync

You can use the signal passing through a multibridge on the analog componet output. G/Y.
It is possible to capture and playback via SDI without using Tri-sync.
Larger installations with numerous devices that require sync then yes.

Monitoring HD via an LCD screen requires the screen to support at least 1920 x 1080 pixels or else it will scale or clip the image.

Recommend.

Apple 23″ Cinema Display
HP L2335
Dell 24″ Dell Widescreen UltraSharp 2405FPW

email pcsupport@blackmagic-design.com if you have anymore questions.

Andrew McLeod
Blackmagic Design