Andrew-R et al,
FFmpeg is good to keep up to date for sure.
But... please refer to section B.4 for more details about upgrading 3rd party libraries. Here is a summary though:
CINELERRA-GG attempts to upgrade to the latest releases of many thirdparty libraries about every 3-4 months. But it is often difficult to keep some of thesethirdparty libraries up to date as their developers switch from tried and true standard tools to newer, less standard tools. As a result in order to build CINELERRA-GG on 2-3 versions of any distro rather than only the most current version, some third-party libraries can not be kept up to date and may even be to the point of no furthe rupdates. In a lot of cases, the updated releases provide little new capabilities but rather are bug fixes that may not even be relevant to CINELERRA-GG’s use.
Biggest problem can be on the older distros, like maybe Ubuntu 16, and with little used packages such as OpenEXR, wepb, libaom, libvpx, x10tv, OpenCV, and Dav1d. I would hate to see users with older distros prevented from using CinelerraGG. I would not update any of these but users who really want them can do their own builds as recommended in section B.4.