Dirpy runs a transcoding platform written using a bunch of libraries that include libavcodec, libavformat, and libavutil, which are some of the same libraries that help drive ffmpeg.

For a more detailed list of a number of the open source software projects in use, check out the Dirpy about page.

   http://dirpy.com/about.py

And of course a huge thanks to all the contributors to open source software the universe over. And thanks for your question :).