Hi,

You can configure H264 preferences for the virtual desktops using the ADMX GPO as per the following article:-

VMware Blast Extreme Optimization Guide | VMware

Or you could use DEM (if you have it in your environment) to target specific users/machines for those that do/don't need it.

The article above also shows you how to identify the protocols and codecs in use by those connected.

Thanks

Andrew