Upscaling 720p to 2160p

1st Official Post

    I just bought a Panasonic 4K OLED TV

    when I plugged in my HTPC to the TV, the only thing I changed was resolution from 1920×1080 to 3840×2160 at 59.9hz in LibreELEC settings

    All my 720p & 1080p videos appear to be upscaled to 2160p ?

    this really stood out with the 720p videos

    My video card temperature used to run at 27 - 34℃ it now goes somewhere from 36 - 52℃

    the CPU temp & useage is also up a little bit

    My old TV is a Panasonic Plasma 1080p

    My HTPC

    LibreELEC 8.2.1

    MB: Gigabyte H270M-D3H

    CPU: i3-7100

    Video Card: Asus GTX1050 2Gb Phoenix

    • Official Post

    Kodi upscales content to the base resolution configured. This was 1080p. It is now 2160p. More upscale processing = higher CPU temps.

    In the past Kodi only had to scale SD and 720p to 1080p which was a small jump in resolution and rendering processing power, and it only changes refresh rate, not resolution, except on some Android devices. Handling 4k (and 8k in the future) requires a code level rethink. Increasingly people have low power devices that can hardware decode 4k media but due to slow ARM CPU's and internal memory bandwidth constraints they cannot handle 4k GUI and overlays. Kodi does a better job of scaling SD/720p to 1080p and it's easy, whereas AVR's and TV's typically do a better job of scaling 1080p to 2160p than Kodi. Kodi attempts to run at the max refresh rate supported so 29.97Hz runs at 59.94Hz etc. but new 120Hz capable screens double 60Hz which requires more processing than available. Kodi needs to evolve the concept of resolution switching in addition to refresh rates, but we nearly always need to manually intervene and impose limits rather than auto-detect capabilities. It's a complex topic with a web of interdependent variables. Kodi developers are currently in the process of figuring out how to technically deliver a solution for this without too much code spaghetti and a reasonable 'configuration' user experience. Oh, and at the same time we're rewriting the Linux graphics stack to support HDR, and other colourspace/metadata things that add complexity to the 4k process.

    TL;DR .. today Kodi works as expected. In the future Kodi aims to be more flexible to get the best output from individual devices.

    The HDMI inputs 1&2 ( these are recommended for 4K ) on new TV are on LHS, so I moved my HTPC to that side temporarily as a 2 metre HDMI cable was longest I had.

    Today I bought a 3 metre 4K cable a $35 Concord brand from Jaycar & set it all up ... Whilst playing video the picture quality is quite noticably down ?

    Video motion was smooth but looked like 720p & when scanning or moving through my Kodi library sideways motion was juddery & not smooth

    LibreELEC settings showed 3840×2160 at 59.94hz - but TV info showed 3840×2160 at 30hz? and I couldn't find anyway in settings to change it

    So I reconnected the 2 metre cable again (stretched it to HDMI 4 after squeezing everything up) .. video smooth and sharp + TV info back to 3840×2160 at 60hz and all is good again

    I thought HDMI was good up to 5 metres ?


    Also to make matters worse I have some speaker issues .. the powered speaker is on the LHS, 1.5 metre RCA cables worked perfectly ..

    but 3 metre cable seem to give a slight lipsync problem which varies from very slight on lower grade video to very noticable on say 1080p etc

    The 1.5 metre cable would fit if I made the LHS powered speaker into a RHS speaker & and the RHS passive speaker as a LHS speaker .. then running sound card RHS RCA output to the powered (now RHS) speaker's input & visa-versa for the passive speaker

    Would this make for any problems ?? all powered speakers seem to be on the left hand side

    Picture & Audio Fixed

    The Concord brand HDMI cables have rather large aluminium looking plug heads, I had 2 of these in the TV's HDMI 1&2 inputs which are very close together & they were squashed in fairly tight against each other,

    HDMI 1 : HTPC picture quality was down & audio was not synced ... but HDMI 2 : the Blu-ray player when I tested it out it had a weird overall strong purple/pinkish tint on startup, video playback etc?

    so I plugged the Blu-ray into HDMI 3 & all the problems have gone

    One more Question .. LibreELEC upscales my 720p & 1080p videos I backed up on the NAS, so if I installed a Blu-ray player in my HTPC would I get the same upscaling to 3840×2160 from my original blu-ray disks?