.MP4 Audio?

I downloaded a live recorded song. Only when I tried to play it I noticed it was a .mp4. When I searched for the song I used the Audio search. I double clicked it and it opened in Winamp. I dragged and dropped into iTunes and it didn't work. I tried renaming the extension to .mp3 and .m4a. The .m4a went into iTunes but when I play it on my iPod, it plays the first few seconds of the song and shuts down the iPod.

Any help would be great.

mp4 is a video file

That's odd because it opened in Winamp but was only audio.

MP4 can contain only audio. But usually it contains both audio and video.

Does anybody know of any software that can convert MP4's to a file that the iPod can play, such as MP3?