Having some very strange problems regarding a codec somewhere. Testing using 1080p60 and 1080p23.94.

Areas of red text are showing a lot more compression than anything else. The fullscreen preview shows a perfect image. It also looks like things are being encoded in 8-bit instead of 10-bit, with clear gamut issues.

The attached capture demonstrates the issue we're getting.

We're also getting the same issue when outputing via Decklink 4k to another Decklink 4k input. This card supports 10-bit.

We used a process of elimination to determine this is definitely coming from vmix/codec being used somewhere.

If we take the video output from the fullscreen HDMI monitor output and capture that again, we don't see the problem!

We have also added k-lite mega pack, just to be sure we've optimised codecs as much as we can - it didn't fix the issue.

Does anyone else have this issue? We're at wits end trying everything.

Thanks Martin!

That's a screengrab of the actual stream itself (Twitch), however the output from a Blackmagic 4k -> Blackmagic 4k input gives the same thing - which should be 4:2:2 right?

I'm not in the studio at the moment, but I'll ask one of the guys to grab me a screenshot of the native fullscreen output also - which will show a nice crisp image of all colours,

We were keen to output with the Blackmagic 4k due to it's own encoding features, and we'd like to avoid having to capture a seperate HDMI fullscreen output (feel that's a bit of a hash),

James

Thanks for that, I have run some tests and the unfortunately the text pixelation is consistent with the 4:2:2 color space.
This shows up particularly with solid red colors, as shown in the examples below:

http://en.wikipedia.org/wiki/Chroma_subsampling

And discussed here:

http://video.stackexchan...-tv-and-videos-on-the-pc

Pretty much all streaming providers including Twitch convert to 4:2:0 and then to H264 so it will be even more evident
in that video.

If your final output will be Twitch, then there is not much you can do i'm afraid and similar results will appear in the output regardless of program used.

Regards,

Martin
vMix

You will likely see better handling of the red in the fullscreen output because PC displays are RGB output not YUV
so when captured on the other end it is still RGB.

Problem is as soon as you record this to a compressed format or stream it to the web you will see the same handling of red on the outputs
so there is not much to gain by trying to keep RGB on the capture card if you will still be streaming it.

Regards,

Martin
vMix

Is RGB output out of the question?

Would it be possible to actually set 10bit 4:2:2 color space instead then? We can't figure out what is setting this.