To enable H.265 on the client, which will request H.265 from the host. If it's available, the host and client will use H.265. If the host does not have the capability to encode in H.265, it will revert the stream to H.264. If the client is a Windows computer or Android device, and it doesn't have the H.265 hardware accelerated decoder, it will revert to H.264. If the client is macOS High Sierra or better, it will revert to software decoding for H.265.
If multiple guests join a Parsec session, and one of those guests does not have the capability to decode H.265, everyone will be reverted to H.264.
This feature will only work on hosts and clients running NVIDIA GTX 900 series or better, AMD Radeon GPUs and Carizzo APUs or later, and Intel CPUs with Cherry Trail or Braswell architectures or later.
How to tell if it is working?
The host and client console will list CLI.codec = H265