问题:

I wish to download a video from YouTube and then extract its audio.

Can anyone point me to some C# code to download a video?

For clarification purposes, I already know how to extract audio from a .FLV file like these.

回答1:

Since all the other answers are outdated, I've written a library that is up-to-date:

http://github.com/flagbug/YoutubeExtractor

回答2:

You can check out libvideo. It's much more up-to-date than YoutubeExtractor, and is fast and clean to use.

回答3:

Gonna give another answer, since the libraries mentioned haven't been actively developed anymore.

Consider using YoutubeExplode. It has a very rich and consistent API and allows you to do a lot of other things with youtube videos beside downloading them.

回答4:

To all interested:

The "Coding for fun" book's chapter 4 "InnerTube: Download, Convert, and Sync YouTube Videos" deals with the topic. The code and discussion are at http://www.c4fbook.com/InnerTube.

[PLEASE BEWARE] While the overall concepts are valid some years after the publication, non-documented details of the youtube internals the project relies on can have changed (see the comment at the bottom of the page behind the second link).