It must be nice to have 4K equipment. Not having it myself I am not qualified to offer help. However, if it helps any, I understand that Shotcut will support bitrates higher than those provided in the dialog menus. It surprises me that your 4K TV has this bitrate limitation. In the Export panel when you select the libx264 or libx265 codec - Rate Control should be anything other than Quality-based VBR. The other three selections allow you to select the Bitrate. One of the selections is 50 Mb/s. HTH -=Ken=-