We could possibly file a feature request for adding ffmpeg to the build image, but it’s not a common request so I wouldn’t be hopeful about it being implemented in a time frame that would be useful for you.
Maybe you’ve already tried this, but just in case: do you think it would work to add this dependency?
If not, here’s one more thing you could try:
If our build environment is missing something other than a ruby, node, or python dependency, you might need to add it yourself. Our build environment runs Ubuntu Linux v 16.04 LTS using x86_64 architecture, so you’ll want to bring a binary that can run there. Since you don’t have permissions to
apt-get install anything, you’re limited to pre-compiled binaries that fit that architecture. A frequent use pattern is to get a copy of the binary we need to build your site, and add it to your repository so you can run it directly during your build. By default your build starts in the root of your repository, so it could be as easy as using
./my-binary as part of your build command.
Let us know how it goes!