I have got a 4K external monitor to connect to my laptop, and have tried for a while to find a media player which can play 4k/hevc/10bit, potplayer so far is the best, as others either not play (VLC) or have various issues (MPC-BE sound borken and video not clear and sharp, MPC-HC no easy HDR), but potplayer also have a big issue, that the sound is constently out of sync with the video (lag behind, and the more you watch the mor lag) when play on the external monitor. I haved tried to play the mkv video on my laptop screen, there is no issue of sound out of sync, but whenever I start to play it on the external monitor, sound is out of sync and start to lag behind. I speculate it is due to the different refresh rate, as my laptop screen have a 60Hz refresh rate while the external monitor have a 30Hz refresh rate, the exernal monitor do support 60Hz refresh rate but my video card do not give this option, so I guess it couldn't suport this rate. So have anyone encounter this problem? And any idea how to resolve this?