Micro Camera Expansion - Blackburst Sync

The new Micro cameras look amazing and the expansion cable is going to open up so many amazing projects and possibilities. I am likely getting way too far ahead of myself, and I assume Blackmagic will release more documentation once the camera is available. But I'm excited and would like to ask about creating a custom sync generator for the BMMCC.

I am interested in syncing up the BMMCC with another device that runs at 30hz (being specific; the Microsoft Kinect). I cannot control the clockspeed of this device, but I can read the relative time of each frame and then estimate when the next frame will need to be captured.

From what I can tell Genlock on the the BMMCC has two modes, Tri-sync (master mode, where it sends a sync signal out) and Blackburst (slave mode, where it lines up exposure to an incoming sync signal).

My understanding of Blackburst is that it's a black frame of video that is sent out every 1/30th of a second (or 1/24th etc). Blackmagic makes a professional device that generates this signal to sync multiple cameras.

But I'm wondering if it is at all possible to generate a custom signal from a device like an Arduino or Raspberry Pi? People have been able to create low resolution black and white video from an Arduino. And from a bit of research I've done, a "black" composite video signal is 0.3v.

Could it really be as simple as sending a few milliseconds of 0.3v power, every 1/30th of a second, to the 5th pin on the expansion cable? Or is there a whole world of video signals, specifications and equipment I am currently ignorant of?

If you've made it this far thank you for taking the time to read my post, and any advice that could point me in the right direction would be greatly appreciated.

Thanks!

So I've found a bit more information on black burst. I cannot post direct links, but the wikipedia article for "Black and Burst" is the most explicit information I have been able to find.

The specifications in the wikipedia article are likely PAL specific (also it's wikipedia), but it appears that blackburst is essentially an brief analog signal at the microsecond level. Arduinos are capabable of microsecond (even sub-microsecond signals) so in theory this should work.

The waveform on the wikipedia page seems to match the Blackburst graphic on the BMMCC product page. But it would be really great to get confirmation that this will work.

Or when the camera is available, if Blackmagic could include the specifications for Blackburst at each framerate/framesize it would be a great help.

Thanks again!

Created an account just to let you know I'm right here with ya.

The BMMCC looks to be an amazing device for hobbyists. It would be nice to get some more technical information. The 4K version looks to be even more awesome.

My main concern come into play when trying to record at 60fps on the 4K version. How would you sync up 2 or more of the cameras with a black burst signal. I'm not sure that's possible, but that's just a matter of my own ignorance.

It would seem we'd need a tri-level reference signal that matched the recording specifications to make sure the horizontal and vertical scans are syncronized.

Alas, this is where my knowledge reaches it's edge.

Anyways, thanks for posting. I suppose we'll need to pressure BM to release more technical literature.

It's not for hobbyists exclusively. Micro is intended to be used in professional scenarios whenever an Alexa or Red is too big or expensive in a situation. I am considering purchasing one myself instead of a Pocket because the Micro overcranks, and I'm not a hobbyist. Will Micro be used by hobbyists? Certainly. I can't wait to see all the doggy-cam and wobbly aerial drone footage on YouTube.

Yeah, definitely didn't mean to imply it was only for hobbyists, but it certainly opens doors that previously weren't open due to prohibitive costs.

As far as drones go, even a simple 3-axis gimbal adds considerable stabilization to your shot. Combine that with a UAV stabilization algorithm and you'll be in great shape. Run the raw footage through an image stabilization analyzer (which may or may not be needed) and you're going to be pretty rock solid. Perhaps even more so than a tripod?

What makes this even more neat is programming your drone to follow a path and using object recondition and PTZ to track your subject.

I think the real weakness of drones is how obnoxiously noisy they are, but beyond that I'm looking forward to seeing what crazy contraptions people come up with - even from the professional world!

Thanks for the replies!

@Isaac - It looks like my initial understanding of tri-sync and blackburst was wrong. Looking at this page: https://www.blackmagicdesign.com/produc ... /expansion the Micro cameras accept either blackburst or tri-sync as an input.

The Micro cameras do not generate a sync signal of their own, so you would need a device that either generates a blackburst or a tri-sync signal and all of the cameras would act as slaves to it.

Blackmagic makes a generator that creates both signal types (at the bottom of this page: https://www.blackmagicdesign.com/produc ... converters) so it doesn't seem like setting up a stereo rig would be too difficult.

I'm still wondering if anyone has had experience generating either of these signals from scratch. In situations where someone needs to sync with a device that does not conform to "traditional" broadcast standards.

@Jason By hobbyist I think we both meant more along the lines of tinkerers, experimenters and hackers. But I'm sure those hobbyists would be interested as well. Really exciting cameras all around.

[Gary Adams]

While this is an interesting question, the genlock signals will need to be the same exact frequency and frame rate as the camera is set in order to work. When a genlock signal changes, there is "some" time where the camera must re-lock to a new signal. Cameras in general are not instantly driven by genlock but are designed to output vertical and horizontal at the same time as the reference signal. The Television Studio Camera can reference to Black Burst or Tri-level Sync which are analog signals that must match the camera settings, or to external program video such as the output of the video switcher in the case of our ATEMs.

Regards, Gary

Thanks for the reply Gary! I had a feeling it was more complicated than I thought.

With that in mind I do have one other question about how genlock works on the Studio/Micro cameras. From my current understanding Black Burst is generally for syncing SD NTSC/PAL, and Try-level Sync is for more accurate syncing of HD and higher framerate cameras. But the Blackmagic cameras accept both types of input.

While the frequency and framerate of the camera and the genlock signal have to be identical, does that mean that the size of the video frame have to be identical as well?

Specifically in the case of Black Burst, is it possible to send an SD Black Burst signal to sync an HD Blackmagic camera provided that it's providing an identical frame rate? (keeping in mind that it would be less accurate than Tri-level sync) Or does "frequency" refer to the "image data" portion of an analog signal?

Thanks again, I really appreciate it!

I am trying to genloc two BMMSC’s (Small portable s3D stereoscopic rig). It looks like the highest resolution output of the BlackMagic design “Mini Converter Sync Generator” is 1080P_30. Could two BMMSC be genloced at 1080P_30 with the BlackMagic design “Mini Converter Sync Generator? Does BlackMagic design have/or have plans to release a Mini Converter Sync Generator with Ultra HD resolutions? The combination of a small portable Sync Generator, coupled with BMMSC’s would revolutionize the s3D capture market.