Decklink 8K resolutions video mode support

[Sidonai-1]

Add support for 8K in decklink video modes, to fully use the 8K Pro decklink cards.

8K 23.98p, 8K 24p, 8K 25p, 8K 29.97p, 8K 30p, 8K 50p, 8K 59.94p, 8K 60p

DCI 8K 23.98p, DCI 8K 24p, DCI 8K 25p, DCI 8K 29.97p, DCI 8K 30p, DCI 8K 50p, DCI 8K 59.94p, DCI 8K 60p

The card should be able to output four 4k60p signals or one 8K60p signal. But I understand there's probably issues with how decklink handles the color mode at higher than 4k30p resolutions so we can only use two of those four SDIs for now. If that's also the only way to add 8K support for this card currently, it's not a bad trade off I think.

Edit: I've been corrected, so this feature request is now only about using the four SDI outputs to get 1 full 8K signal. But the last changes made in #1433 probably will cover this once the random delay between signals gets solved.

Thanks.

[krzyc]

The card should be able to output four 8K signals (on paper) if I'm not mistaken?

It is not possible to output 8K signal on single link 12G-SDI (11.88 Gb/s), because 8K bitrates start from about 18 Gb/s. BMD states that 8K Pro supports SMPTE 2082-11 which should allow dual link 8K@24/25/30p, so maybe 2 outputs are possible. Color space is another problem - if card do not accept BGRA in this mode (as reported on forum) then decklink producer must be modifed. And 50/60fps will of course require quad link (SMPTE 2082-12).

[Sidonai-1]

I see. That actually makes more sense, thank you for clarifying.

[Julusian]

The decklink sdi does expose 8k videomodes and the connectors can be grouped, so it looks like we can send it 8k frames. But I think this is blocked by #1367, as there isn't any point adding 8k video modes which wont be possible to output to a decklink

[Sidonai-1]

The decklink sdi does expose 8k videomodes and the connectors can be grouped, so it looks like we can send it 8k frames. But I think this is blocked by #1367, as there isn't any point adding 8k video modes which wont be possible to output to a decklink

Now with the custom resolutions it's probably fine that 8K video modes are not available, since we can just create them for outputs.

Regarding inputs at 8K (one 8KPro card in QuadSDI mode), are video modes needed to accept that frame size as a valid input?
Yesterday I tried to get it to work but no luck. I only did a quick test with the camera at 8K50p, does the input suffer from the same limitation as the output(no rgb frames)? If that's the case, when I try 8k25p it should just work or we'd need to add 8K25p as video modes on the server?

Thank you.

[Julusian]

From a quick skim of the code, we don't care what the exact input format is, only doing so for logging reasons.
It doesnt do RGB, so that may or may not be an issue, but it is operating in 8bit YUV, so is still needing some amount of conversion, which could upset the decklink.

As it didn't work for you, I would guess that any amount of conversion is too much for the decklink. Which is understandable, even repacking pixels in 8K frames on a cpu will not be cheap.

I asked the other week if they had any advice for a different rgb vs yuv issue I have found, and their recommendation was to use a compute shader to do the format conversion. (this was talking 1080p). Which I have started working towards, but isnt finished enough to merge any of yet.