4K HDR playback on 10.2Gbps HDMI chip projector?


#1

Hi Sam and co, I have a Vero 4K (July update) connected to a Denon 2300 which is then connected to an Epson 7300 projector (10.2Gbps HDMI chip :frowning: ).

In playing back 4K HDR remux’s the projector is reporting 3840x2160 23.97Hz 8bit 4:4:4 BT.2020 HDR signal. This is without the ‘444,10bit’ in rc.local. Logs here https://paste.osmc.tv/herazipaho

If I add the ‘444,10bit’ string to rc.local and play same content the projector reports no signal as I guess I’m over the bandwidth of the chip. Logs here https://paste.osmc.tv/apixosudik

Setting it to ‘422,10bit’ I get a funky green tint to the Kodi UI and film
Setting it to ‘420,10bit’ I get no picture at all eg no Kodi UI even


#2

The team’s been looking into this and a fix is on the way. We’ll ping you when there’s something to test.

In theory, 4k x24x10bit ought to sneak under the wire on bitrate but who knows?


#3

Hi

Hopefully the issue is now addressed with the following commit:

I’d appreciate it if you could test this and provide feedback before we potentially release this as an update to other users. To test this update:

  1. Login via the command line
  2. Edit the file /etc/apt/sources.list
  3. Add the following line: deb http://apt.osmc.tv stretch-devel main
  4. Run the following commands to update: sudo apt-get update && sudo apt-get dist-upgrade && reboot
  5. Your system should have have received the update.

Please see if the issue is resolved.

I also recommend you edit /etc/apt/sources.list again and remove the line that you added after updating. This will return you to the normal update channel.


#4

You will still need to issue 422,10bit. Next step - to make it automatic.


#5

Yep.


#6

Wuhoo, that works!

Projector is playing content (without green tint) and reporting 3840x2160 23.97Hz 12 bit 4:2:2 BT.2020 HDR

Note, its reporting 12bit not 10bit yet 10bit was set. Any reasoning on that?


#7

What’s the original bitdepth?


#8

12-bit probably makes sense actually


#9

Don’t know where this came from, but it suggests 422,10bit is illegal

0caps


#10

Should I force it to 422 12 bit?

Just spun up my old shield to see what it was set to and it was set to 422 12bit!!


#11

Why not? Can you actually see a difference in the picture??


#12

Yes – it needs to be 12-bit.

Sam


#13

With it set to 422 12bit it wont play 4K 29.96Hz content (some GoPro demo footage). Any ideas on that one? Need logs etc?

Nvidia shield can play these (3840x2160 29.96Hz 12 bit 422 bt.2020 SDR)


#14

Yes – please post some logs.
When you say won’t play, what do you see?

Another HDMI cable may be worth checking.

Sam


#15

Sorry, I should have been more specific; the content plays as my AVR is playing the sound but the projector is showing no signal once the content starts. Please find logs here https://paste.osmc.tv/afugiwajov


#16

Skimming the log, is it trying to force it to twice the framerate (59.94) even thou the content is 29.97? If so then my HDMI chip cant handle 4K @ ~60 and alas no signal.


#17

Yes – this is the problem.
You can override FPS, but it’s not recommended.

See 25Hz content playing back at 50Hz for an example


#18

YCbCr 4:2:2 pixel encoding is by HDMI specification always 12-bit. If fewer than 12 bits are used, then the valid bits are zero padded below the LSB.


#19

The Shield can do it, but you must knock the GUI into the right mode before watching the movie. They never fixed the colourspace switch, just framerate. This leaves navigating your menus very clunky and when you go back to a regular 1080p source it’s comes out as full RGB making the picture super black and contrasty and still at 24hz.

You must switch back for 1080p to avoid this.

The very real issue is most projectors, even if you can stomach high lamp mode, don’t have enuff bobbins to display HDR properly until you start getting into £30k+ units, you do get a little bump in colour tho which is nice especially on a good projector, so while not great or close to HDR it is worth it still.

Hopefully the fix will just be what you play is what you get. i’m not aware right now of any media player that will do colourspace and resolution and HD audio switching properly even with 18gbps chipsets in the chain.


#20

I will have to check when I get home but I’m almost sure on my shield its set to 1080p 59.94Hz (or 60Hz) 422 12bit and it both resolution and frame rate switches. Aware of colour space switching issues, hence bought the Vero.

So regards 29.97 content, is it that it should be doubled eg thats the norm and in the case of the Shield its not doing the norm and playing it as 29.97 and hence my projector can play it.

If this needs a separate thread then please split it.