To build and use libavif (with avifenc/avifdec) in an Ubuntu Docker container with all dependencies, change into this directory and run:
docker-compose run libavif
This should install all necessary dependencies, including manually building and installing all supported codecs as shared libraries, and finally building and installing libavif/avifenc/avifdec. It will then drop you a shell running in the container.
If you just want to force a (re)build and skip the interactive shell, run:
docker-compose up --build --force-recreate libavif
Note: This build process will take a while (15-30m or more depending on your machine).