Delivering video across all browsers

I have a source video. In order t开发者_StackOverflow社区o play it in all major browsers (IE7+, Chrome, Safari, Firefox), how many formats do I need to convert the video to? Will using a single .mp4 file be sufficient? What exactly is the webm format, and is it required that I additionally convert my video to this?

In addition, what are some open source video players that would be able to play this format(s) in all browsers?

flowplayer is the opensource player which is easy to integerate in your website. It can play formats like flv and mp4 in all browsers.

here is a link to it:

http://flowplayer.org/

Another opensource player is JW Player. you can find it here:

http://www.longtailvideo.com/players/

Hope this helps.

In terms of supporting the html5 video tag, I believe firefox and opera only support ogg/vorbis and I don't see them getting .mp4 support in the very near future (.3gp and .mp4 are patented). You will need to fall back to a plugin like flash or silverlight, as I imagine the above players do for xcc.