444 10bit output from vero 4k

New owner here and i would like some help. When playing back HDR content output is at 8bit instead of 10 bit. The tv goes into HDR mode but is in 8bits. I tried this command

echo ‘444,10bit’ > /sys/class/amhdmitx/amhdmitx0/attr

but i get a permission denied message

I have a 4k oled tv and an hdr compatible receiver. All other devices are working fine with hdr so its a problem with the box.

Any help greatly appreciated. Am using putty to login in to the vero if thats of any relevance. Thanks.

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That only works as root.

Otherwise run:

echo "444,10bit" | sudo tee /sys/class/amhdmitx/amhdmitx0/attr

I’m going to add an HDR option to Kodi to make this simpler.

Hi Sam,

I’m a new happy owner of an Vero 4K. Is there a chance to downscale 4k output to the following parameter:

4k24p hdr 420 10bit?

the situation is as follow:

I have a projector (Sony VW320ES) which is 4K HDR capable at 24p but only with Chroma Subsampling to 422 or 420…

Vero 4K is playing all Videos in 444 hdr 8bit. Only when I put a HDFURY Linker between Vero and Projector I get it running in 10Bit Mode after I added the follwing command:

echo ‘444,10bit’ >/sys/class/amhdmitx/amhdmitx0/attr

and the linker is doing CS to 420 following input (10bit)…

is ther a chance to get directly always 4k420 or 10bit HDR? or also 4K422 could work this I would need to test…

Thanks in advance


HDMI spec dictates as follows:

Hopefully this clarifies what can be achieved, and at which refresh rates.



I know this sheet but what I need to donthat the box is sending out 4k24p 10bit hdr?

When I use mentioned command but with 422 I get a green screen and output is again 8bit only…

This would suggest something in the HDMI chain does not support this format.
Have you tried a direct connection to the projector? If this works then we should check EDID when connected to other intermediary devices.


I‘ll check but is there also a chance to keep it running in this mode constantnly sonthat I don‘t need tonuse the command line?

But as I wrote before, when HDFURY Linker is doing the Chrome Subsampling to 422, the Veronis switching correctly to 10bit. I only want that 4K HDR Videos switch correctly into 10 Bit Mode

Yes – if you set it in rc.local it’s permanent, what have you tried currently?

Are you saying that you would only like HDR10 content to change to BT2020 and everything else to stay as 8-bit Rec709? This has already been requested by another user and is being worked on.


Good morning. In my opinion the best solution to this problem is the following.

1080p(BT.709)@any frame rate: YCbCr 4:4:4 10 or 12 bits Bt.709 output

2160p(BT.709)@23.976hz, 24hz, 25hz, 29.97hz, 30hz: YCbCr 4:4:4 10 or 12bits BT.709 output

2160p(BT.2020)@23.976hz, 24hz, 25hz, 29.97hz, 30hz: YCbCr 4:4:4 10 or 12 bits BT.2020 output

2160p(BT.2020)@50hz, 59.94hz, 60hz: YCbCr 4:2:2 10 or 12 bits BT.2020 output

I wrote 10 or 12 bits because i dont know the highest bit depth vero 4k can upsample. Everything should be played back according to the source’s colorspace. No conversion. Except for when a BT.2020 video is playing and the tv/projector/display cant handle hdr and the player needs to convert to sdr. The gui can be in 1080p bt.709 60hz 8 bit. If it can go up to 10 bit or 12 bit ( still 1080p bt.709) without messing the table i posted above is an added bonus. Less banding.

In my case Inwould need as follow:

1080p content should play 1:1 as source

4k24/25/…p 10bit hdr content should play in 4K24p 10bit hdr 422

4k50/60p 8bit should play in 4k50/60p 8bit

Major issue is that my projector is hdr capable but only 422max

is there any eta for the release of this request?

Then an option should be made available in the menu.

Color depth option: Auto, 8bit, 10 bit, 12 bit ( if available)
Chroma upsampling: Auto, YCbCr 4:2:2 , YCbCr 4:4:4

Auto should work as the table in my previous post( or for the max available options through display EDID)

10 bit should be the minimum for HDR BT.2020 content and 8 bit for SDR Bt.709. Having 10 bit enabled should not activate BT.2020 signaling if a bt.709 file is playing whether is 1080p or 2160p. Colorspaces should remain intact.

But is there any planned ETA for the testversion for this workaround?

Well Sam should answer that i guess and confirm if such a configuration is possible . I know kodi has a lot of limitations but that is how all video players should handle video for accurate playback. Like my previous post.

What @Yiorgos suggests is similar to what I have in mind

Currently there should be no negative effect of 10-bit Rec2020 being sent for all content. Others haven’t reported this issue so I am not sure why you only discovered it recently.

It should be possible to only switch modes when needed. It may not always be useful to have a long list of options as only some options are available at specific Refresh Rates. Perhaps an HDR ON/OFF option is all we need, with robust logic on how to handle different types of video


There is a negative effect that i tried to demonstrate with the samples i sent you. If you force bt.2020 and the source is bt.709 the colors are all wrong. I dont know what equipment other people and/or if they are playing this kind of content. Changing colorspaces when there is no need to i think is wrong.

Most of the users have normal TV‘s which are completely capable of 4k60p 12bit HDR with max brandwidth…

At currently available projectors it‘s different. To have them capable for max brandwitdth you need to buy a projector for minimum 14500€…

The other native 4k projectors are only capable as I mentioned above… Same for the e-shift projectors. for both versions the hdmi port have brandwidth limitations…

But is this workable or a release is in nesr future for a test version?

The colour space shouldn’t actually be changed here.
I understand that this is problematic for you though. We can definitely work on a solution for this.

This could probably land in late January for testing.


I have the same problem like Joker1982 with my Epson 9300 (Epson 6040UB / 5040UB) projector.
The Epson can’t play 4K 444 10Bit.

I found this document for the Epson HDMI Chip.