Seems like most of the current 4/8/16 H.265 NVRs are using the HiSilicon Hi3798M processor. In the datasheet it lists:
Video and Image Encoding
H.264 BP/MP/HP@level 4.2 video encoding, maximum
1x1080p@30 fps or 2x720p@30 fps decoding
Variable bit rate (VBR) or constant bit rate (CBR) mode...