Install libx265-doc by entering the following commands in the terminal:
sudo apt update sudo apt install libx265-doc
Description:
H.265/HEVC video stream encoder (documentation)
libx265 is an encoding library for creating H.265/High Efficiency Video Coding (HEVC) video streams. . This package contains documentation for the command line encoder and the shared library.
Homepage: http://x265.org
Version: 2.6-3
Section: universe/doc