For true Cinemascope content, i.e. where resolution is equal to the 2.39:1 aspect ratio (e.g. 3840x1608), black bars are NOT encoded into the video but have to be added by the app/TV. When playing certain HDR10 content, those letterbox bars appear gray rather than pitch black.
For true Cinemascope content, i.e. where resolution is equal to the 2.39:1 aspect ratio (e.g. 3840x1608), black bars are NOT encoded into the video but have to be added by the app/TV. When playing certain HDR10 content, those letterbox bars appear gray rather than pitch black.
Examples of such content can be found on YouTube - Real 4K HDR: Cosmos Laundromat in HDR
MrMC devs came up with a workaround, using transparent color instead of black which does not suffer from the improper tone-mapping (see https://github.com/MrMC/mrmc/commit/e686c40a50c8474300571dc62b0a5a8c3b519604 and https://github.com/xbmc/xbmc/pull/15225).