White highlights turning black

[Larry Lippke]

We are using PTZ optics cameras connected by SDI to an ATEM video switcher, and then feeding with SDI from the switcher into a computer with a Blackmagic video card. The computer is running OBS which we are using to stream to YouTube. We have configured the cameras to specs suggested by PTZ Optics, and the images on the ATEM switcher monitor appear fine. However, we have one particular issue that only appears in OBS that is related to rendering white or reflected areas coming off our organ as seen in this image. In fact, when our organist is playing the organ, the backs of his hands sometimes also turn black. In this image, you see that there is a reflection on the organist bench that has also turned black. I don't even know what to name this issue. Someone told me it was video noise, but this is not characteristic of other video noise I've seen.

Any suggestions on where to direct our attention?

 

[FerretBomb]

This could be a number of things; my first instinct is that you have a full/partial range mismatch somewhere in your chain. Full range goes from 0-255, Partial only does 16-235. So if a Full source sends 236, a Partial receiver may overflow that to a negative value rather than clamping it at 235.
As they look fine on the ATEM, I'd expect this to be the ATEM outputting in Full, and the Blackmagic capturing in Partial.

Probably easiest to look through the ATEM's manual and see if there's a way to set it for Partial range output. Getting Full in from the capture card can cause significant issues in the digital pipeline, and Full range can only be recorded locally... it can NOT be used on streamed video. OBS is actually hard-coded to only use Partial on the streaming output.

 

[BluePeer]

sounds for me that the input use a "not supported" or wrong "configured" Input signal
like the atem sends a XX Bit Colorrange YY signal to the blackmagic
and in obs the settings use a YY Bitrate Colorrange ZZ or similary

edit: sametime post like Ferret other words same issue ^^

 

[Larry Lippke]

Thanks for your suggestions. I have not been successful in even finding what range the ATEM switcher outputs, much less finding any way to change that. I did see in OBS the ability to change the input setting between full and partial, and while I found that changing one to the other had some impact on the quality image, it was a very minor change, and did not resolve the issue.

I continue to search for the answer.

 

[BluePeer]

8/10 of my think is a setting error but a cable issue or a wrong/broken cable (HDMI level) i think can another reason

 

[FerretBomb]

Thanks for your suggestions. I have not been successful in even finding what range the ATEM switcher outputs, much less finding any way to change that. I did see in OBS the ability to change the input setting between full and partial, and while I found that changing one to the other had some impact on the quality image, it was a very minor change, and did not resolve the issue.

I continue to search for the answer.

If you mean changing the range in Settings->Advanced, you REALLY should not do that. Change it back to Partial.

You may be able to hard-set the capture card in the Video Capture Device properties to a given color range here:

You may also be able to use the 'Configure Video' button higher up on the Properties screen to use the Blackmagic's own config panel to do similar, force a color conversion.
I still believe that the issue is a full/partial mismatch, especially given that the brightest spots are what's turning black. It's a clear overflow.

 

[Larry Lippke]

I realized that Blackmagic's Media Express app also uses video from the Decklink card. Using that app showed no problem with the video quality. I then installed two other video streaming apps, and both of them worked fine (xsplit and vmix). I even ran a test YouTube Live today using Vmix, and the quality of the image on the livestream was very good. And I made no particular adjustments in either of these other apps; just used those apps "out of the box." So my conclusion is that there is something in OBS that is not working right for me. BTW, I just realized that I never mentioned that I'm using OBS 26.1.1.

 

[BluePeer]

The only thing that thies means that OBS not detect the signal.
I never used external Hardware video Sources for myself. but try to bring to flow on some friend setups.
if your Input Signal Settings not match your Video Source Settings , then this drive you crazy.


The different is that other software have special detect scripts for that hardware what OBS not have.
OBS use a i call it "Driver Control System"

which is an open standard to talk to these devices. this ensures that most devices can be addressed. But only works well if the manufacturer sticks to it, which is often not the case with cheap manufacturers, or with various expensive providers where there is no interest in third-party software because their own is marketed.

so if a video source not offer the correct options or work not instand correct then there is default 2 reasons
-The driver does not understand the request and not answer
-The driver understand the request and send data but in a Special form for the distributor software

Related to this thread i used google a bit and some information confuse me
in every thread related to a blackmagic capture card this called not "VCD - Matrixswitcher"
you not specified the card so this can be correct idk
there many post about there need to be set over the media express from BM and OBS settings and select the correct Blackmagic device (Most screens i seen called "Blackmagic xxx" or "declink xxx")
but one fact i ever seen is that users have problems to config it, after struggle and found the way required works correct
what i found out in this short excursion is
that you need to base config the card with Blackmagics media express and then select this options on the correct Blackmagic device with the settings from media express. on select wrong device or settings not match. the result can go from No view to issues like we have here

So for me i am out here its a Special Problem related to the configuration of the card.
i have no know about the correct way to setup this
wish you good luck on find this , or that some one with that know post a how to setup/ important steps information
Blackmagic at it self does not do this (thats what i found in blackmagic board)
wish good luck

 

[CircadianPie]

Has anyone figured out an official way to fix this? Running a similar setup (Canon PTZ -> Blackmagic capture card -> OBS) and I'm getting the exact same issue. Doesn't happen in any other program, only OBS.

 

[CircadianPie]

Has anyone figured out an official way to fix this? Running a similar setup (Canon PTZ -> Blackmagic capture card -> OBS) and I'm getting the exact same issue. Doesn't happen in any other program, only OBS.

Update: Fully reset all settings and the issue goes away. Not a permanent fix but it got everything back to normal for a while.