messed up 50p only had single link into 7Q

Y

yachacha

Well-known member
I set up my F35 for someone else to use this weekend. I totally spaced on 50P needing the dual link for 422.

Basically if you set the camera to 50P 422 and plug only into SDI A of the IF box it pops up as 25P into the 7Q, but it shows a complete picture. The recorded file shows input 25P and Project 29.97. It skips slightly during playback on the 7Q. On the computer it plays without skipping but has interlacing artifacts.

Once I plug the SDI B in, the 7Q switches to 50P input and records full 50P files.

So if I recorded only SDI A output from the IF box while the camera was set to 50P 422, did I mess up the footage (missing 1/2) or is there a way it can be converted to 23.98 without interlacing artifacts?
 
Good question. The interlacing artifacts might have come from the project being 29.97. If it was 25P recorded as 25P it is definitely possible to get it to 23.98, you just slow it down.
 
I think I can explain what happened, but you might not like the answer.

You're missing half the data, and what you have is composed of only one field of each of the fifty frames per second, hence the interlace artifacts.

The video stream is formatted as 25p, but it's not every other frame - it's half of every frame.

Figure it this way. SDI spigots A and B both are on the same Genlock. They're both feeding out simultaneously. At the time that progressive video frame 1 is ready, frame 2 isn't. So the camera loads odd fields to spigot A, even fields to spigot B. Then, when frame 2 is ready, it loads even fields to Spigot A, and odd fields to spigot B. Or something similar. I'm not 100% certain. But the point is, it's using an interlace trick to manage the doubled frame rate in real time.

Mitch Gross might be able to give you a better technical answer - I remember they had to do some extra coding to support this issue with the F35.

Honestly, short of making a half rez video file that only preserves even or odd fields you might be out of luck. By going half rez, making a seperate file of even and odd fields, then rejoining by intercutting ABABAB, you might be able to approximate a 50p file to slow down to 23.98. But slowing from 25p to 23.98 won't fix the interlace issue.
So, your single spigot d
 
Thank you, this is what I thought. It is the same as recording the pink/green image that comes from 1/2 of the 444 23.98 in a way.
 
Sooooooo.....

I've just had to deal with what I believe is the exact same issue with 59.94p on the F23. With my footage I've been able to remove the interlace effect, and recover a 29.97p stream (interpreted as 23.98p). The solution is highly technical, but I could take a look at your footage and see if I can fix it.
 
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