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NDI Black frames in vMix


I'm dealing with a problem that vMix support team and PTZ Optics support team doesn't have a solution for it yet :(

They heard about it but they don't know why this happens.

In few words, I will describe my problem.

From time to time, in vMix, I have couple of black frames from my NDI cameras (PTZ OPTICS 12x). They don't have a pattern, they just appear and ruin my recording.

What I discovered since I have this problem and trying different stuff:

Camera web interface settings:

I have black frames when I use Encode Protocol H264.

I have grey frames when I use Encode Protocol H265.

I didn't test the MJPEG very much because of the big lag.

If I rise the bitrate to the maximum - 20480kbps, I have more often  those black frames.

If I lower the bitrate to 12000kbps (NDI HIGH PROFILE), I still have those black frames, but less often.

Once,  I didn't have any black frames at all on one camera, but I had on the other one. I checked the settings and I discovered that the "good" camera, had 4000kbps bitrate. 

I have gigabit network, I don't think that a 40000kbps (from 2 cameras) bitrate should be a problem at all. The cameras are powered through the network cable from a TP LINK POE SWITCH with 5 ports.

I attached a photo with my network monitor. When the black frames appear, I can see a spike on the network like the one in the picture.

Maybe I can tune some settings from the camera menu to get rid of that black frames but I don't know the meaning of them. Maybe you can help me.

Fluctuate Level, Slice Split Enable, Split Mode, Slice size.

I do recordings more often then streaming, so I need the highest bit rate because it matters in my productions. If the cameras are working without black frames at's too low for me. I need every bit of quality than I can get.

Based on my informations, maybe someone can see a solution...

Thanks for your help.

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2 people have this question

did you ever solve this?

Hello Stephen,

There has been an update to the NDI HX driver that seems to have solved the black frames issue in vMix.

So if you are seeing a similar problem I would recommend downloading and installing the latest NDI Tools from NewTek. 

And if you are still having problems please reach out to us in Support, you can

Submit a Ticket or

Give us a call at  484-593-2584 

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