id3v2 build is a custom vulcan build downloaded from (https://github.com/soft-dave/heroku-buildpack-id3v2/raw/master/id3v2.tar.gz)
It doesn't do anything else, so to actually compile your app you should use buildpack-id3v2-tag to combine it with a real buildpack.
To use this buildpack, you should prepare .buildpacks file that contains this buildpack url and your real buildpack url.
$ ls .buildpacks ... $ cat .buildpacks https://github.com/soft-dave/buildpack-id3v2 $ heroku create --buildpack https://github.com/soft-dave/heroku-buildpack-id3v2 $ git push heroku master ...
You can verify installing ffmpeg by following command.
$ heroku run "id3v2"
Copy the snippet above into CLI.