genlock broacast monitor

[cananball]

Hey guys, i don't know if this is a question I should be asking a video engineer but I'll throw it out there.

I just bought a Mojo to send external video from my PTLE8/003 on Win XP. It hasn't arrived yet but i have been test running some genlock scenarios.

I have a MOTU Digital Timepiece and Burst Electronics BS-2 blackburst generator i would like to genlock everything to and output on a Sony PVM-1271Q broadcast monitor. This is an OLD monitor (80's I think) but i got it for free and it has a REF IN so thought it would be cool if i could genlock along with the Mojo for really precise sync.

I have been sending for video signals through it and playing with the external reference but getting funny results. When on internal Ref, Sony monitor looks great, but when i switch to Ext Ref the colors distort(almost like messing with the tint control) and it starts to roll kinda diagonally to the bottom right corner. This happens any way i send the black burst.

Digital Timepiece in internal video generator
Digital Timepiece slaving to BS-2 Black burst generator
BS-2 directly


Is the genlock capability fried on this thing? All frame rates matched and is set to NTSC (Sony is NTCS/PAL switchable)

Also, how important is it to have the monitor genlocked too? I see most guys here seem to be using consumer LCD's and plasmas which obviously are not synchronizable, so it cant be too bad right? At least its got to be better than Quicktime in pro tools.

Your thoughts are appreciated.

[Postman]

The ref input might be disfunctional. In those days, some rare equipment actually distinguished between "video reference" and "video black", the latter is what is typically used these days. It is highly unlikely your vitage Sony monitor would have a problem with either, I will guess. I expect you could loop the video input signal right back into the reference input (terminate one but not the other!) and get the same image whether the monitor is set for video or ref sync.

For your use, there is absolutely no benefit in using a separate reference to the monitor. ALL analog monitors perfectly genlock to the video signal, they are incapable of anything else.

Many modern plasma and lcd monitors genlock to some frame rates but not others, or some types of inputs but not others. It is hard often times to know without testing.

To answer your last question, it is important but sometimes not critical to have a genlocked monitor. If you have access to a Syncheck, you can measure your system's performance and discover if things are fully genlocked or not.

[cananball]

I expect you could loop the video input signal right back into the reference input (terminate one but not the other!) and get the same image whether the monitor is set for video or ref sync.

I did try this, or maybe backwards, video signal to ref in loop back to video in. regardless when on external it is screwed up no matter where it comes from, when i unplug ref in it goes black, no picture at all.

ALL analog monitors perfectly genlock to the video signal

I figured this was the case, what else would it sync to

To answer your last question, it is important but sometimes not critical to have a genlocked monitor.

please enlighten me, where would genlock be a must on a monitor? Not in audio post i guess?

[Postman]

To answer your last question, it is important but sometimes not critical to have a genlocked monitor.

please enlighten me, where would genlock be a must on a monitor? Not in audio post i guess?

I'm not sure we're talking about the same thing. When I said "genlocked monitor", I meant a monitor that lock's its internal screen refresh to the incoming video signal.
I think it is a highly important consideration, but many people don't seem to care and are perfectly happy with the small visual sync errors.

An external ref input on a monitor was important as it allowed editors and technicians to easily see if a particular video feed was correctly sync'ed to the house ref and whether a particular video deck was playing video from an edit mode or not. That is not what I was talking about.

[minister]

If you have the BG-2, then it is as simple as can be and is NTSC. (I think I still have one of those hiding here someplace.). The BG-2cb, is NTSC/PAL switchable and also switchable bet/ color bars and "burst". If you have the 2cb, verify your setting are correct.

Next, connect the BG-2 to the Motu piece and verify that you have NTSC lock. I don't have one of these, but there must be a way to verify that it is locking to a NTSC signal.

Next, double-check the Sony PVM-1271Q manual for settings.... I don't know this monitor so well, but... IS the 75 Ohm termination ON when you connect the EXT REF? It should have a termination switch.

How are you feeding the SONY video right now? RGB?

[cananball]

If you have the BG-2, then it is as simple as can be and is NTSC

BG-2 is simple straightforward NTSC only no color bars.

Next, connect the BG-2 to the Motu piece and verify that you have NTSC lock. I don't have one of these, but there must be a way to verify that it is locking to a NTSC signal.

Digital timepice does have a "lock" indicator that appears if you sync it to external blackburst which does light up.

Next, double-check the Sony PVM-1271Q manual for settings.... I don't know this monitor so well, but... IS the 75 Ohm termination ON when you connect the EXT REF? It should have a termination switch.

>
it does have selctable termination which was properly set.

How are you feeding the SONY video right now? RGB?

I am feeding with compostite. I havent recieved the Mojo yet but i know it can send component but is it RGB or is it yByRy? (original mojo not sdi)

[minister]

Hmm...Postman's postulation that the EXT Ref input of the Sony may be broken might be correct.

Just a last check:

Originally Posted by cananball

I am feeding with compostite. I havent recieved the Mojo yet but i know it can send component but is it RGB or is it yByRy? (original mojo not sdi)

Composite from what? A genlocked NTSC source?

[cananball]

Composite from what? A genlocked NTSC source?

No i was feeding it NTSC from a dvd player not genlocked. I have no decks and am waiting for my mojo in the mail. Tried to genlock incoming dvd video to house sync from digital timepiece. Could this be a problem? Might i get different results when sending genlocked ntsc from mojo? I will try.

[daveall]

[QUOTE=
I have been sending for video signals through it and playing with the external reference but getting funny results. When on internal Ref, Sony monitor looks great, but when i switch to Ext Ref the colors distort(almost like messing with the tint control) and it starts to roll kinda diagonally to the bottom right corner. This happens any way i send the black burst.

Composite from what? A genlocked NTSC source?
No i was feeding it NTSC from a dvd player not genlocked.
[/QUOTE]

If you're doing both of the above at the same time, then the result is normal.

To display a non synchronous source correctly, use internal sync.

The usual reason for externally genlocking a monitor is so you can tell if your signal source is in time with house sync. In this case the video signal is not synchronous with the genlock signal, so it doesn't display correctly.

[cananball]

In this case the video signal is not synchronous with the genlock signal, so it doesn't display correctly.
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Thats great news, thanks.

Along thoes lines...follow me, I'm not sure if this will work. Digital timepiece can sync to any incoming video signal, and can display a video overlay of its functions(timecode, framerate, sample rate and device status, which would be cool to be able to access so here is what i propose.

Send blackburst to mojo and monitor, send genlocked video from mojo to Digital timepiece (synchronized video), send DT video out to monitor composite in. This would allow me to see overlay on video signal but would this maintain sync? It seems like everything would be on same reference even though DT doesn't receive blackburst directly.

____

Also sony monitor has a loop through out for video reference. i can use this to safely daisy chain to mojo? My blackburst generator only has one output. I figure i need a multi output unit but the loop through makes me think otherwise.

Would a bnc T work as well on the output of generator? I'm assuming mojo ref in is termanated so through monitor or T on generator is only way. To me it seems strange to send sync to monitor BEFORE mojo since the signal routing is the otherway around.