How to convert mpeg-4 to mp3 or wave format using pure python on Google App Engine?

I'm working on a project, using Python running on Google App Engine. The project must allow users to upload mpeg-4 audio file for others to pl开发者_如何转开发ayback. Is there a way to convert mpeg-4 to mp3/wav on the server side?

Could anyone offer a solution to this? Any help is greatly appreciated.

Google App Engine is designed for lightweight HTTP requests and user-facing Web application.
Video/audio transcoding is an Heavy activity that would probably deplete your available CPU quota in no time.
If you can, outsource the transcoding Task to some third-party service like Zencoder, Heywatch or Encoding.com .