Since I upgraded to 8.95.2, and on all the nightly builds since, I have experienced a slightly strange behaviour with regard to playback of SD channels played through TVH. They appear to be in the wrong aspect ratio - stretched sideways. When I look at the same channels in their HD versions the picture fills all of the screen and is not stretched sideways. I cannot seem to find a setting that rectifies this problem with SD channels.
Also when using SD channels, any messages that pop up in the GUI are in very low quality SD. If I go to the full GUI screen (with the channel playing in the background) the GUI reverts back to full HD quality.
I had the same problem.
Just remove all SD resolutions from your whitelist.
This greatly improves picture quality, GUI overlays and fixes the aspect ratio issue.
Assuming the video stream has a 16:9 aspect (Not the content itself but framing of the stream) make sure the TV itself has aspect for the whitelisted display mode configured for 16:9/full screen. Otherwise if TV is 4:3 and Kodi is assuming an output of 16:9 the image will appear distorted.
Assuming the video stream has a 4:3 aspect (Again not the content… this is independent of whether content is widescreen or full screen) then there are two options:
Don’t whitelist any SD resolutions that allow 4:3 aspect ratios.
Use whitelist, set Kodi to Stretch 16:9 video and use TV remote to set 4:3 aspect ratio. This effectively results in 4:3 pass-thru but the UI framing in Kodi will appear somewhat distorted while playing SD content.
Any other option will result in distortion / loss of resolution.
In all cases with SD whitelisted resolutions the UI will appear with lower resolution. Personally I prefer using whitelist pass thru because for me it results in noticeably better picture quality relying just on display upscaler. It varies with display and can be a pain/not worth the effort to deal with.