The free edition of NoMachine software on the user's computer (i.e. "NoMachine" used as a client) and also Enterprise Client support H.264 hardware decoding on Windows and Mac hosts with hardware accelerated video cards (GPUs). No further action is required. Note that if the screen resolution is bigger than 1920x1080, NoMachine falls back to VP8 by default. It's possible to override this behavior (see: https://www.nomachine.com/FR09L02830).
On Linux hosts or when the Windows/Mac computer doesn't have a GPU, it's possible to use H.264 software decoding.
Both the free NoMachine product and Enterprise Client provide the H.264 decoding libraries as of v. 6.6.8 (ref. https://www.nomachine.com/SU04Q00203). If you're running an older version you may either upgrade or follow instructions below to install FFmpeg.
To manually add a H.264 decoder on the client: just install FFmpeg from the repository of your Linux distribution or install a Windows or Mac build from one of the sites providing it.
For example, you can download the package for Linux, Windows or Mac from https://www.ffmpeg.org/download.html.
rename the avcodec and avutil libraries into: libavcodec.so and libavutil.so
and place them in:
On Mac OS X
rename the avcodec and avutil libraries into: libavcodec.dylib and libavutil.dylib
and place them in:
Download the 32-bit shared build and place at least the following libraries:
There's no need to rename the libraries.
Verify that H.264 codec is used
To verify if the H.264 codec is used, run the NoMachine menu panel (ctrl+alt+0 or click on the page peel on top right of the window) in the session window. Click on Display -> Change Setting: the codec in use should be written on the bottom page on the left.
Support for H.264 on the server side
Since v. 6.6.8, all the server packages for Windows, Linux, Mac and Raspberry include the AVC/H.264 software codec.
If you are running a previous version of the software you may either upgrade or build the libx264 by following these instructions:
for v. 6 and 5 https://www.nomachine.com/AR09M00863
for v. 4 https://www.nomachine.com/AR10K00695