What’s the best (free) software to automatically transcribe a 50-minute speech?

What’s the best (free) software to automatically transcribe a 50-minute speech?

I gave a speech extemporaneously that was recorded. I need to write a new one, and would like to base it on the one I’ve already given. I just need to get the basic points of what I said — perfect transcription not necessary.

This is very time sensitive project, and would prefer to find a free solution.

Suggestions?

You may be able to find demo speech recognition software on the website below. At the very least, you’ll find someone who can transcribe it, but it’s very likely they will want to be paid.