To avoid duplicate posts and bring all the information together, I’m making this post about FEL Support in CoreELEC. The current thinking is that Amlogic CPUs with the suffix -k don’t support FEL while those ending in -j do support P7 FEL and P4. Both -j and -k support P5, P8, and P7 MEL. In practice, there are three candidates but not all of them play FEL in CoreELEC.
S905X4-J such as the Kinkhank G1 and Ugoos X4Q Extra do not play FEL in CoreELEC.
S922X-J such as the Ugoos AM6+, Ugoos AM6b+, Minix U22X-J (Max), and Amazon FireTV Cube 2nd gen do support FEL if an updated version of dovi.ko is used. See this post for more detail. With the modified dovi.ko, CoreELEC can support Profile 4, FEL, CMv2.9, and CMv4.0. However, CMv4.0 only works in Display Led mode if your TV supports it.
According to testing performed by DMDreview, S922X-J devices send CMv4.0 data unlike Oppo players. Additionally, R3S3T_9999 determined that these devices do not ignore RPU data in several rare cases when the Sony x800m2/x700 incorrectly does. As a result, the brightness might appear slightly difference between S922X-J and Sony devices. DMDreview and R3S3T_9999 agree that an almost imperceptible difference exists in the video output between Oppo, Sony, and S922X-J devices. These differences are likely due to Oppo using Nearest Neighbour while the the AM6b+ uses bicubic to convert from 4:2:0 storage to 4:2:2 transmission standards. In short, extensive testing demonstrates that CoreELEC’s FEL support exceed that of both the Oppo and Sony players.
While Amlogic code suffers from a fairly severe bug that converts all non-YUV444 content to BT.601 prior to re-encoding it to RGB resulting in incorrect color output, this bug does not affect Dolby Vision content.
Currently, support for FEL is under heavy development. FEL appears fairly stable as of the 20240404 nightly of the -ng branch. However, enabling Settings → System → Disable GUI scaling can cause playback issues for some users. The team is actively working on perfecting support for FEL on the S922X-J
S928X-J such as the Tencent Aurora 5X and UGOOS AM8 are not supported by CoreELEC due to a missing driver. The CoreELEC team has been attempting to obtain this driver since October 2023.
For the Content Mapping Version - CMv2.9 CMv4.0 the key element for most people will be that the associated meta-data (RPU - Reference Picture Unit) can be passed to the TV for processing in the Dolby Vision Engine on the TV end, i.e. so called tv-led dolby vision. In Kodi this is labeled: Display Led (RGB tunnelling)
Alternatively if the CM RPU is processed on the device / stb (i.e. the player), then that is LLDV (Low Latency Dolby Vision) or so called player-led dolby vision. In Kodi this is labeled: Player Led (YCbCr 4:2:2).
For Player Led: on S922X-J with current dovi.ko it is only CMv2.9 capable, so in that mode it cannot take advantage of CMv4.0’s additional metadata.
For Display Led - as the CM RPU is processed on the TV it is the TV’s capabilities that matter - e.g. an LG E8 from 2018/19 for instance is still only CMv2.9 and thus still cannot take advantage of CMv4.0’s additional metadata. However recent TV which are most likely CMv4.0 can and will take advantage.
Display Led is better (even if only CMv2.9) as the Dolby Vision Engine in the TV can take into consideration its mode of operation, the current settings and have generally more in-depth knowledge to base the tone mapping from the CM RPU on, and if the TV is CMv4.0 then you get that step up on top.
For UHD DV Blu-Ray from what I understand most are still mastered with a target of CMv2.9, so the number of actual CMv4.0 discs out there are not many at present.
For those wondering CMv4.0 is backward compatible, i.e. a CMv2.9 device will see it as CMv2.9 data and process as such - thus only missing out on some specific extras that CMv4.0 brings.
Profile 4 is supported (but now considered obsolete), Profile 7 is the one used on UHD DV Blu-Ray.
If you want a device that can process UHD BluRay Dolby Vision in all it’s glory: MEL/FEL plus CMv2.9/CMv4.0 RPU metadata as true tv-led (TV permitting), and also do pass through audio for True HD Dolby Atmos and DTS-HD MA X, then these are the only devices - currently (Ugoos AM6B+ / Ugoos AM6+ / Minix U22X-J MAX) outside of bona fide quality blu-ray players and playing physical disks.
I personally have a Ugoos AM6B+, no regrets with that choice.
It is not yet perfected (what ever is!), but the CE team in particular @Portisch are working hard to make this the best platform and bridging the gap between Kodi’s frame based approach the AMLogics stream based approach to media - to make the experience seem-less and trouble free.
So far any G12 device that was DV certified and can run CE, have been able to play DV FEL.
This includes the AM6+, U22X-J and 2nd gen FireTV Cube.
I’m skeptical that the G12 SOCs have any special hardware capabilities over the SC2 SOCs that let them handle DV FEL. It seems more likely it’s due to differences in 4.9 and 5.4 kernels and DV handling.
I’m betting that even an DV certified s905y2 SOC could play FEL in CE.
The Minix U22X-J MAX is discontinued by the manufacturer.
@YadaYada I really hope that other devices emerge that can support DV FEL. I’d love to personally test a S905X4-J device, but can’t afford to buy a third device this year.
I personally hope that this will push manufacturers to take CoreELEC more seriously and provide more support to the team. For me, the Tencent Aurora 5X is a truly beautiful device and it’s a shame that Tencent decided to stop supporting the CoreELEC team. I also hope that SEI robotics will S905X5-J chip in their upcoming device and work with the CoreELEC team. More choice is always the best.
Do advise me to sell my Dune HD homatics and buy Ugoos Am6b+?
Unfortunately, I couldn’t find someone who has dune hd homatics and Ugoos am6b+ to get advice from him about that.
my concern have the best device to play all DV Metadata via Coreelec OS.
Thank you @Vasco for your reply. Is the Ugoos am6b Plus the best device for playing more DV profiles without conversion or if you would please recommend me better than this device?
Don’t have a definitive explicit source I can point to, just what I have picked up in forums about better mapping to fit the panels capabilities, I.e. it is not baked into the signal - which certainly makes logical sense.
The closest I can think of something more concrete - though a little tangential - was Stacey Spears on LG OLED where the TV was using its light sensor - before Dolby Vision IQ was announced - to adjust with the RPU in cinema home mode on those TV I think from the C9 or CX models - indicating they adjust at TV side.
I recall that was on the blu-ray forums.
There are also plenty of comparison videos out there from dmdreview reset_9999 etc. which show differences.
Ultimately there are numerous factors and I take the view you are the person looking take a critical eye and if it looks correct to you across a variety of content then that’s what matters, for me tv-led is quite a bit better in my setup.
side note: From what I understand LLDV was initially for gaming to get the most of the Dolby Vision experience without any lag - and because Sony had under powered SoC in their first DV TV’s it was “repurposed” for standard content as well.
If you are using LLDV with AMLogic based CE then probably will want to set the sys parameter or code to set it to follow the TV (sink) luminance values - it obtains from the HDMi connection otherwise if I am not mistaken it will set to 50-4000
even has a newer processor than S922X it’s S905X4-K.