Why Libav?
Is there any reason you picked Libav (avconv) over FFmpeg?
Should probably change brew install ffmpeg to brew install libav also
The reason is that I think avcodec is a more active project, with better documentation and more releases. However I think that the dependency on libav can be removed, currently I am only using it to parse the file and read the metadata...
It gives a rather cryptic error if you install ffmpeg instead of libav
events.js:72
throw er; // Unhandled 'error' event
^
Error: spawn ENOENT
at errnoException (child_process.js:980:11)
at Process.ChildProcess._handle.onexit (child_process.js:771:34)
that is simply that it did not find the avconv command line tool... I guess I should invest some time in better error reporting :)