Cadet RGB Encoder + BMD Mini Analog->SDI = :-(


#1

Hi All, I have a Blackmagic Design Analog to SDI Mini Converter that doesn’t seem to like the composite video from my Cadet RGB Encoder. The symptom is a very jittery picture that jumps sideways.

I’ve tested the 525i SDI signal into both a BMD Web Presenter and an ATEM Studio HD (current model) with the same results. I tested with a cheap Canon camcorder and got even worse results (dropouts), but I get a clean conversion with my Andor 1.

Any ideas?

Thanks!


#2

Sounds like an issue with the Analog to SDI if you are having trouble with two sources. The issue sounds like a sync tolerance problem. Have you tried updating the Analog to SDI to the most recent firmware?


#3

The plot thickens:

I talked to BMD tech support this morning and ran through all the tests while I was on the phone. The camcorder’s composite output magically started working fine (it was previously the worst of the three), which means 2 out of 3 voted against the C2. The proof came when I plugged the camcorder’s composite output into the C1’s input and everything cleared up. This works with the Andor 1 also.

So it appears the BMD converter is picky.


#4

Thats not too surprising. Both C1, Vidiot, and the original Video Sync Generator use the same sync gen architecture, which is based on a 13.5MHz voltage controlled master clock (same as BT656 SD pixel clock timings.) It appears that the resting frequency of the clock is outside the expected range of the Analog to SDI, which explains why it works when genlocked to the timing of the external device. So you have some options: sync all your gear to a master reference signal, run the C2 through a frame sync/TBC, or try to modify C1 to get its native frequency in range. I would be happy to help with the latter, you could start by trying to add 10K pull-up and pull down resistors to the VCXO CV input.