Extracting Sync information from Ursa Mini 4K Monitor Output

Hi guys,

I am trying to get sync information from my Ursa Mini 4K while shooting at 120fps. I am trying to input the sync information to an arduino. I have attempted using a sync generator but these are only designed to work at speeds up to 60fps and appear to be functionless when “Off Speed Recording”.

I am thinking about reverting to my previous idea of extracting sync information from the SDI outputs on the Ursa Mini. I’m aware that the front SDI output gives a down converted HD signal, which will surely introduce some delay and the rear SDI output gives 12G-SDI ultraHD output and doesn’t specify if it is downconverted but will presumably have some delay. I am not really bothered about delay as long as the delay is consistent as I can compensate for consistent delay in my arduino code.

I want to know if anyone can comment on methods of extracting the sync information from the SDI outputs. I have asked Blackmagic support team to comment but they are sadly unable to offer any help regarding this.

I have purchased this chip from Texas Instruments: http://www.ti.com/product/LMH1981. Part of me thinks this will work at decoding the HD signal but I am unsure. It’s hard to tell what to do next so any help would be appreciated.

Thanks,
Felix

Why are you creating topics for every question about this project... Found about 5 topics about the same project.. Keep it clean and 1 or 2 topics

The problem is that the chip you choose will not work with the ursa.. This chip does only accept analog sync signals like blackburst and tri-level sync. The Ursa outputs HD/3G SDI...

Standard Analog Video Sync Separation for NTSC, PAL, 480I/P, 576I/P, 720P, and 1080I/P/PsF from Composite Video (CVBS),
S-Video (Y/C), and Component Video (YPBPR/GBR) Interfaces
Bi-Level & Tri-Level Sync Compatible
Composite, Horizontal, and Vertical Sync Outputs
Burst/Back Porch Timing, Odd/Even Field, and Video Format Outputs
Superior Jitter Performance on Leading Edge of HSync
Automatic Video Format Detection

You will need a SDI deserializer to get a Sync signal off a SDI signal.. Which will give you a FVH sync.. Frame Vertical and Horizontal timing..

This can be done with a Semtech chipset.. Problem is these chipsets are hard to put on a PCB. (100 ball BGA) Need a lot of control from the microprocessor.. And still no guaranteed succes that the SDI output is even sync with the 120FPS high speed shooting mode.. All depends on how BMD software engineers have coupled things inside of the camera.. Might be complete off sync..

I remember a post of BAZ that make a Genlock ref signal from SDI with a SDI to Analog converter..

He used this to genlock cameras on the Return SDI feed.. Not sure if this will work very steady and how much it does screw up the sync part.. But might want to investigate that.

For the Texas chip.. You might want to buy a complete test PCB.. Easier to interface to the arduino then a loose chip that you have to solder all sort of hardware to..

They don't mention which chip they used.. But i bet it is one of those TI chips.. Guess a simple email to them will clarify that..

https://shieldrock.com/proto.html

Sorry about the multiple topics I did worry about that but I thought that the previous topics seemed to have reached natural conclusions and justified an updated topic with the latest information. Not very good at using forums, sorry. I will keep this post current about updates with regards to extracting Sync and update the other topic with regards to using the sync generator.

I have sent sheildrock an email to ask about the suitability of their products for this project. Thanks for the tip, I hadn’t found them before.

Even if you extract the sync information from the SDI, I don't see how you will get the 120FPS signal. If I understand correctly, the 120FPS is a recording rate - the camera will only output a maximum frame rate of 60 on its SDI connections.

Ursa Spec Snippet

Ursa Specs.png (88.32 KiB) Viewed 2068 times

Regards,

Dave.

Yes he will get 60Fps maximum.. But if that 60Fps is in sync with every other frame captured he can make a trigger on that make a flywheel sync that will trigger 1 in 2 sync pulses.. The arduino needs to fill the gaps by timing in between.

At Least he knows when to trigger roughly... Then he need to make an adjuster to the arduino to advance or hold the strobe of the led a little bit off the sync to get the correct timing between frame and lighting..

But yes if the output video is in some way coupled to the internal clock of the FPGA. Which also triggers the readout of the sensor.. This would be 1 way to do it..

Lot of work and no guarantees..

If the recording is locked then it’s easy just to count lines until he is half a reference frame in - would be easy as the LMH1981 provides both H and V sync. Much easier still if he runs the project at a broadcast rate 50/59.94

Regards,

Dave

Yeah sure.. But he need high speed for this project..

Not sure what the subject will be.. But he need to trigger the lighting based on when the frame is captured..

And yes the project would be easier on 50/60 fps.. And maybe he should try this first as he can trigger on every pulse.. And expand from that experiment.


I doubt if the Arduino is fast enough to capture every line trigger. He uses 8 or 16 mhz clocked Arduinos.. But then there is a major overhead in the arduino code.. So acurcy is not Arduinos best move..

He is trying to do this