Video Sync ref and Word Clock

[RichT]

I'm just getting my head around various clocking issues at the moment and few things clarifying on how they work.

Effectively the video clock (is this running at the frame rate?) needs to be connected to a video sync ref circuit (does it need to be black burst or will any signal do?), which effectively mulitplies it using a PLL up to audio clock rates (eg 48000Hz), which an audio clock can sync to.

I've also noticed that relatively few recorders (even those with timecode) have video sync ref in.
Only ones I can find are Tascam HD-P2, SD 788T (none of the others), Sonosax SX-R4 and Nagra VI.

The Tascam's the only one I can currently afford, I even had one for a while but preferred the Edirol R-44 for music recording and sold it...

I'm also unsure if recorders with timecode in and no wordclock in (eg Edirol R-4pro, Fostex FR-2) will sync using the AES input (although meaning it can't be used) when used with a lockit or similar.

 

[Noiz2]

The first thing you need to figure out is, do you need any of the above? Your question sounds like you have been reading old textbooks from the analog video days and are trying to follow a work flow that is not necessary (for the vast majority of people on this list).

But first... Blackburst is the black between fields in a video signal. It's used to mask the electron gun jumping back to the top of the screen.

As such I'm not sure how often it's used for sync now since progressive streams are not split into fields. But it's a pretty low res sync signal.
Wordclock is a digital signal and I believe runs always at the audio sample rate.
Superclock is wordclock at 256 times the sample rate. Superclock was something that Digidesign came out with but a number of others also used.
Time Code is just a bunch of numbers and is not nec. in sync with anything. The exception is VITC TC which is a video only TC that lives in the part of the signal where the blackburst is and so is locked to the video scan rate.

BUT we are now in the digital world and things have changed a bit.
With file based workflows everything is what used to be called "self resolved", meaning they are so stable that for narrative work (under 10 min takes) there is essentially no drift.
TC is strictly used now as a "positional" reference since it is nowhere close to accurate enough for clocking digital streams.

To lock a bunch of boxes today you need Wordclock and TC and (another one I'm forgetting... BlackBurst??). Anyway this trio is called "tri level sync" and you will see it listed on some boxes.

Back to my first point though. If your not doing multi camera/ multi recorder shots and/or super long takes you don't need to worry about all of the above. Your camera and recorders are not going to drift by a significant amount over a "normal" take. And when I say significant I mean say 1/100 of a frame or so.
You can use a stupid slate and sync the old fashioned way in post and be happy. Or go new-school and use a guide track and Pluraleyes.

Where you start needing tri level sync is with a bunch of cameras shooting at the same time for long takes. Say concert footage. In that case you really need everything to be locked in for an hour plus and wiring everyone up is the only way to do it.

TC on it's own is only a way to sort of line stuff up. Files don't have continuous TC only start stamps. So even if your TC is dead on it won't keep the boxes from drifting.

With analog recorders you could use TC for maintaining sync but that died with analog tape.

 

[Noiz2]

I'm also unsure if recorders with timecode in and no wordclock in (eg Edirol R-4pro, Fostex FR-2) will sync using the AES input (although meaning it can't be used) when used with a lockit or similar.

Digital recorders MUST sync to a digital in to use it. If your clock is not set to the digital in and you record from that digital in you will get pops and glitches and usually the recorder will throw an error and just not work at all. But again TC is not used for sync in the digital world, only as a positional reference (i.e. "start here").

 

[RichT]

Thanks very much for the info- just to give you some context I'm quite new to working with video but have been doing music recording for some time and I'm looking to get some freelance work in this field. I'm also thinking it's more than likely I'll end up doing some concert recording in the near future so could do with knowing how to deal with video interfacing professionally (which looks like it'll involve hiring equipment).

re: digital conncetions, I was more concerned whether you can effectively use AES input instead of worclock to sync (whether the recorder is recording from it or not). I'll probably have to check manuals here.