Wireless Genlock?

[Robbie Brandon]

Thanks in advance for checking this out! I am designing a video system for a local church and have run into a bit of a problem. Of course, I know this is the place to go to find the pros. So, a brief rundown of the system:
4 - Sony PMW-200's (3 on tripods, One on steadicam scout HD)
1 - Black Magic Design Atem 1 M/E switcher
3 - PCs (1 for editing, 1 for switcher, one for graphics(Pro Presenter))
Wireless Communications.

Here is the issue. Latency is of the utmost importance to these people. The latency they are experiencing on I-Mag (the projectors in the venue) isn't really that bad. So, I have to genlock the entire system in order to gain back the 1 frame of latency that would otherwise result from the Atem's internal frame synchronizers. So, How do others use a steadicam and get around the genlocking issue? I can find a wireless HD-SDI solution, no problem. But I seem to have hit a dead end on the syncing issue. What would be the result if I genlocked 3 cameras and the switcher, but not the 4th camera? Would I still get good fades in the switcher, or would there surely be anomalies? I truly appreciate any help you can give.

P.S. Mods, feel free to move this to the appropriate place. Thanks!

[Dave Gish]

Originally Posted by Robbie Brandon

So, How do others use a steadicam and get around the genlocking issue? I can find a wireless HD-SDI solution, no problem.

For big productions, I believe they have little boxes that you jam once and they'e locked for the rest of the day, if not longer.

For low budget stuff, they still line things up manually in post using the slate, or just clap their hands in front of the camera, or if there's only one camera some people use wireless audio.

[Robbie Brandon]

Thanks for the reply! I realize there are ways to deal with the sync issue in post, but im more worried about Imag (i.e. whats playing on the projectors in the venue) Without genlocking the system, I gain latency(per Black Magic). So, I was wondering if there is a way around it for a steadicam? or maybe a wireless solution?

[Gene Gajewski]

This is an interesting topic.

Genlocking is usually only required for live video production. This is because switchers (historically) operated directly on the camera's signals. Sometimes, these switchers can handle a little isochrony - they can perform a one-line delay to match slight timing phase differences. Frame locking is whole 'nother ballgame, though. A frame lock device is used to conform a non-genlocked source to genlock, and it can be up to an entire frame off. These are used for feeds from non-genlockable sources such as really old analog recorders

Since time code is often needed for post production - video studios provide both time code and genlock.

It appears AFAIK that Hollywood productions simply jam timecode to their cameras from the master timecode generator, which is hooked up to an external sound recorder. They don't use genlock. They may use ClockIt/LockIt devices externally which have a very low drift. The video timecode is matched to sound time code during edit.

I did a look see around the net and the only thing I could find easily was these devices.

Timecode Buddy Complete System | Trew Audio

It appears to be a wireless system somehow using WiFi to sync a remote receiver. It claims to send both genlock and timecode - but I'd test it first with the explicit guarantee that it can be returned. It seems a bit dodgy to claim synchronous genlock over wifi.

I would think making a wireless genlock/time code device might be a good garage shop opportunity for someone. Wish I had the wherewithal to do it myself.

[Joe Lawry]

Not easily, and not with a BMD ATEM switcher. You need a switcher with a frame store in it.

Plus you get delay in your hdsdi link. I just finished flying on a low budget live to web stream 10 camera shoot. 6 EX1s, 1x PMW350 on a jib. 2x FS700s. 1x Sony PTZ camera.

HD SDI was the only thing fed into the mixer, and I had a IDX Camwave Link on the back of my EX1 on the sled. All the other cameras were locked fine within the mixer itself. Mine was out of sync by a few frames however.

[Robbie Brandon]

thanks for the responses. interesting. I wonder how the big live productions deal with the iMag latency. seems like I see sreadicam operators in these settings sometimes...

[Butch Henderson]

It is my understanding that Time Code and Genlock are two seperate things.

Genlock is a black burst signal that gets all the cameras starting their scan of the frame at the same time, so that cuts, dissolves and effects are clean.

Time Code is a set of numbers associated with each video field for synching later in post (for the most part)

Would it be possible to put a frame synch (that is properly genlocked and timed) on the signal coming from the steadicam prior to the switcher? 1 or 2 frames is not a lot of delay, if it synchronizes with the rest of the system properly