How to Export an AE video | 3840x2160 (4K) | 59.94 (fps) from Adobe Media Encoder version 14.03

Hi Leon, it's likely you need to adjust the render settings in Media Encoder to get better results ... but we need to know what your current settings are. For instance are you currently using the H.264 or H.265 encoder or something else? What is your data rate in Media Encoder etc.

However as a stop gap - have you tried using the H.264 format (under 'Export settings' in Media Encoder in the  'Format' pulldown menu) and then selecting in the 'Preset' pull down menu and selecting 'Match Source - High Bitrate'. This is a good place to start if you are new to the program. It should provide good quality encodes.

If the above is still not good enough you can use higher data rates by accessing the 'Bitrate Settings' found in the 'Video' Tab in Media Encoder. You could increase your 'target bitrate' up to (say) 20Mbps or higher. 

A bit of experimenting on your part may be needed to get the best results. Remember that higher bitrates (and quality) will result in larger files and different codecs will provide different results. Once you have a setting you think is good enough - you can save that setting in Media Encoder for future use.

Good luck.