4K video formats/codecs

[ufaforwork3]

??
Does anyone know which codecs / formats work for the 4K playback.  I have experimented with quite a few 4K videos and some work and others do not.  Is there a guide or list of which formats / codecs will work.  Some my files are MKV with different codec formats and some MP4's.  Two are mpeg/HVEC - will not play at all. (67.7 Mbps) and  One is AVC plays but stutters (48.7 Mbps).  One is AVC which plays fine (62.8 Mbps).  Two more are AVC MKV, which play fine (low bit rates, 20 and 23 Mbps)) and 3 are MP4 low bit rate ( 27, 28 Mbps) which also play fine.  More info available if needed. ?
Any info would be appreciated.
Thanks

[looun]

it's simple see the codec with mediainfo:

• HEVC(H.265) / AVC= True UHD
• x.265 /x.264= fake  HDMI-in capture or  home made .

On this web site  there are the only TRUE UHD/HDR demo http://demo-uhd3d.com/ ,than there only 8th crack film.
Other are  fake(HDMI-in capture)  or  home made(1080 upscaled to 4k).

PS lot of video "Title" report HEVC / AVC, but mediainfo show the right x.265 /x.264 encoding = fake