Google has some pretty good software for this, thought it might be internal. When they have their "Talks at Google" events, there's a screen off to the side that provides real-time translated subtitles.

There's at least one talk where the speaker addresses this system, and tries to get it to transcribe funny stuff. Can't remember which one exactly, but it might be this one with Randall Munroe (xkcd).

https://www.youtube.com/watch?v=zJOS0sV2a24&list=UUbmNph6atA...