Learning about Dolby Vision and CoreELEC development

[doppingkoala]

@freddy

Forgot to set
12 bit
4.2.2
We are successful now

Maybe I need to hardcode this and the 4k gui settings

Good to know it’s working now for someone else.

[freddy]

Yes!!
Please do

More user friendly the better

I dont remember having to do that in your
5.15.119 kernel build.

Just 4K gui and reboot
Unless was set as defaults?

[doppingkoala]

@freddy

Unless was set as defaults?

Yeah, it was hardcoded as the default.

Didn’t matter what was set in the giu as that functionality was broken original 5.15 kernel build.

[Archttila]

In this picture link in the top left corner under GENERAL, bottom line: HDMI mode: HDMI, HDR Type: SDR It should be Dolby Vision instead of SDR…

I tested with at least 10 different Dolby Vision content.
Is this an LG OLED (CX) FW bug or real info?

latest CE21 nightly
LG OLED CX latest firmware
calibrated Dolby Vision Cinema mode (Calman)

[freddy]

This build us for amlogic SoC Without Dolby Vision compatible/certification.

If you are using Am6b Am6plus there is no dovi.ko in kernel.
And is not required with Doppingkoala Build!!

Please test on other amlogic s905x4, s905x, s905x3, etc

Currently testing on Tanix Tx5 Plus Deluxe S905X3

[doppingkoala]

So it turns processing the metadata ahead of time is enough to make a -no build work properly.

312.9 MB file on MEGA

Pretty much the same as the previous -ng build in Learning about Dolby Vision and CoreELEC development - #341 by doppingkoala. Differences are:

• Less inital setup needed
  **Any refresh rate for the gui will work.
  ** No need to set a 12-bit 422 mode.
• Changed path for options, i.e., L5 crop timeout is now

echo 3000 > /sys/module/amvideo/parameters/osd_L5_timeout_ms

[borygo]

You’re doing fantastic job man! Thank you!

[alui1]

Will this build work on the X96Air (S905X3)?

[doppingkoala]

should work on anything that runs coreelec

[alui1]

Thanks. I did a new install (20.5 Nexus ng) and updated with the version from post #349. Turns out that DV works with my X96Air … Played a few files and found that profile 8 looks perfect, but with profile 5, the colors are off. Not sure how to fix that … Also, for some reason, I can’t ssh into this build. My putty window just disappears after I enter my login/password. I do have SSH turned on.

[doppingkoala]

@alui1

but with profile 5, the colors are off. Not sure how to fix that …

That is known. It is a result of this work only playing with metadata, but profile 5 content also requires the actual video signal to be modified (polynomial reshaping) which hasn’t been looked at. I have no idea how that could be done on these devices.

That said, it is possible on these unlicensed amlogic boxes as *SMC (the related project that’s acronym apparently cannot even be included in a post…) does it as a part of playing back profile 5 content as HDR10/SDR. Unfortunately, no details as to how they did this could be shared, apparently it is subject to a NDA.

This is my best guess

@doppingkoala

For example, my thoughts are that these devices don’t have enough cpu power to do the reshaping process in software. The operations are also non-linear which rules out doing the reshaping with color-space conversion hardware. It does appear though that the VPP has a 289 element video OEFT mapping LUT per channel, I’m wondering if this could be used to approximate the reshaping - if it is only a polynomial reshaping. Another thought was the reshaping process could be done entirely in GPU code - people play games on these devices so it should have the power for these fairly basic calculations.

May eventually look at this given that p8, p7 MEL, p7 FEL as MEL playback seems to work without any issues now.

@Portisch (or anyone else that knows CE well) Any suggestions on how polynomial reshaping could be performed?

---

@alui1

Also, for some reason, I can’t ssh into this build. My putty window just disappears after I enter my login/password. I do have SSH turned on.

I’ve done nothing to do with ssh for this build and others have had no issues.

Might be an issue with known_hosts on your computer not matching after you updated - I’ve had this happen. Try deleting the relevant entry in your known_hosts file.

[alui1]

Never mind the ssh problem. I think my sd card must have been corrupted. I re-install everything from scratch and the ssh problem went away. Also, now I can reboot normally whereas before I had to reboot via the “Reboot to Coreelec” app from android …

[freddy]

@alui1

new install (20.5 Nexus ng) and

Is this a typo ?
Thought new build was back to the New Order
5.15.119 kernel?

Have not tested yet
New build from Doppingkoala

[alui1]

@alui1

I did a new install (20.5 Nexus ng) and updated with the version from post #349.

No, that wasn’t a typo. I wasn’t sure whether the -no build would be compatible with my X96Air, so I chose the 20.5 Nexus ng build along with the update in post #339 (not #349 as stated in my original post; that was a typo). Sorry for the confusion.

[freddy]

All is good
Nice to see others testing Doppingkoala Builds

I would encourage others to test as well!!!

[xmlcom]

@doppingkoala

So it turns processing the metadata ahead of time is enough to make a -no build work properly.

312.9 MB file on MEGA

Hi @doppingkoala unfortunately it is crashing on my GSKX.
https://paste.coreelec.org/BankruptPerjury
https://paste.coreelec.org/AndrewsHopeful
dmesg | paste
https://paste.coreelec.org/RunwayMaxine

[doppingkoala]

Doesn’t look like you did

@doppingkoala

Set kodi to use 12-bit 422 with a 3840 x 2160 gui resolution. Enable the option “Disable GUI scaling”. Reboot

Check the settings.

If you still have problems, post a photo of the settings page so I can confirm they are correct, then we can move on to looking at what else is the problem.

[xiux]

20.5 build is very good, i have dolby vision + atmos passthrough working, tv is lg c1, box is x96 air, 905x3

but video will stutter when subtitle is shown when in dv mode, in non-dv mode it’s all good.

the blank screen when pausing, stuttering when gui showing doesnt bother m that much, but stutters during subtitle is a dealbreaker.

let me test 22 build now

[doppingkoala]

@xiux

but video will stutter when subtitle is shown when in dv mode, in non-dv mode it’s all good.

This generally or for a particular file? I’m not seeing issues with subtitles for a few files I tested.

---

@xiux

let me test 22 build now

How did that go? There is a slight difference in the implementations that may be relevant here.

[doppingkoala]

Minor update from the -ng version in Learning about Dolby Vision and CoreELEC development - #341 by doppingkoala. See that post for setup + known issues.

248.02 MB file on MEGA

---

Change:
Added automatic adjustment of L1 metadata. The value of the L1 min_pq is clipped to be at least the value of source_min_pq. The value of the L1 max_pq is clipped to be at most the value of source_max_pq. This matches what was observed in the hdmi tunnel captures.

Can disable this with

echo N > /sys/module/amvideo/parameters/L1_adjust

Re-enable with

echo Y > /sys/module/amvideo/parameters/L1_adjust

These can be changed while playing a file and have immediate affect.

---

With this change, the only differences between the DV output of this build and an official device I’m aware of are:

• This build will output a L5 crop. This resolves issues with positive lift values. See test files in @R3S3T_9999 Offset positive Lift Test folder for examples.
• The video signal remains in YCbCr format. This differs from devices that use a dovi.ko that unnecessarily do a color space conversion.

For anyone that tests, please report any other differences in the displayed images output from this build and an official DV device for any content that is playable as p8.1.