Various issues with Vero 4k

Just to update that I’ve been able to replicate the issues with Serenity as well. 45s clip uploaded to my GDrive of the affected area, behaviour is the same as with JW2.

Clean log:

Hi @sam_nazarko

Any progress please?

Yes I believe you need to do the 444, 10bit and/or 422, 12 bit fixes.

If you don’t do this you will be outputting 10 bit HDR content in 8 bit HDR. Even though the HDR metadata is putting your TV into HDR mode, and the content is still following an HDR EOTF, the video output is only 8 bit by default and 8 bit bit depth is not great for HDR content, which needs 10 bit to preserve the original content…

I checked this with an HD Fury Vertex (which displays all sorts of HDMI diagnostic information), and without the command line instructions the HDMI output was reported as 8 bit only.

Am hoping to post more on this over the next few days.

I haven’t had a chance to look at this yet


If that’s the case, Sam any chance we can get this “fixed” in the next update, just so it works properly without having to guess :smiley:

Probably not next update – but we can make some testing available.

Setting via rc.local should do the trick for now.


Hi Sam,

am I right in saying that setting via rc.local will stick until reboot?

Will I need to ‘unset it’ for playing normal 8bit material?



Scripts or commands in rc.local are started every boot.

If it works as expected, no :slight_smile:


so I create a file called rc.local and put this in it do I:

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

Being a bit dim perhaps, but don’t want to mess up



Not just any rc.local file:

That’s great thanks for your help

I’ll try that as soon as I have some time tonight


Can I check if the playback issue everybody is having with JW2 is at the 1m 50s mark (JW takes the motorcyclist out with his car door)?
Are there any other glitches in the movie?

For me, it’s at that point, too. And only there.

Yes, that point for me also - which is what my cut sample covers. I’ve not tested the rest of the movie, I’ve only been watching <4k content on the Vero so far till this is looked at.

Any news yet @sam_nazarko?

It’s been 3 weeks now since you said a couple days. Appreciate you may have bigger issues on your pad but as a customer of the Vero when it’s not playing content properly it’s not the most encouraging to have zero updates…

Unfortunately not.

As the problem can be reproduced with this clip on a variety of platforms, we deferred it to the SoC provider to investigate.

They’re still not happy with the encode but they’re seeing what can be done.

If I understand correctly, Serenity and JW2 are the current affected files?

I don’t believe I offered a timeframe for this and apologise if I did by mistake


Thanks @sam_nazarko that’s good to know. I hadn’t expected a fix in short time but there had been no update to say the SoC provider is investigating so knowing that’s the case is encouraging.

I can’t see why they aren’t happy with the encode, all the samples provided are direct dumps from the UHD disk so no encoding has been done.

As for other titles, none I’m aware of just now but haven’t been watching any 4k content on my Vero. If I find more I’ll update the thread with samples.

Is that correct that the command “echo ‘444,10bit’ > /sys/class/amhdmitx/amhdmitx0/attr” needs to be input after every reboot to output HDR in 10bit mode, it will not persist?
Can anyone help me what i have to do for creating a rc.local file correctly? I don´t understand the wiki…

So i have to edit the /etc/r.local file with nano, insert the line

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

save it and do a reboot and that´s all and the HDR content output is in 10bit?


Took a bit of time to look at John Wick 2 myself today.
It freezes on the motorbike and the decoder gets stuck and has to be reset.

[ 1571.026078] [0]H265 dec err local reset.
[ 1571.026216] [0]nal type 39, discard 1
[ 1571.026474] [0]init_decode_head_hw: (3840, 2160) body_size 0xff0000 header_size 0x7f80
[ 1571.026479] [0]hevc_recover HEVC_SHIFT_BYTE_COUNT=bbf10c8

Can you try, before playback:

echo 16 | sudo tee /sys/module/amvdec_h265/parameters/dynamic_buf_num_margin

and confirm if this fixes the stop? I think we just need a little more headroom.

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