Do you know what video codec is used for messengers?

I'd like to know the video codec 开发者_Python百科used for MSN, yahoo, QQ or any other XMPP messengers.

Thanks for help.

For video codecs it's something like this:

• Skype: On2's VP7.
• Yahoo! Messenger: JPEG 2000, i.e. only I-frames.
• Google talk: H264 and others.
• MSN Messenger: Siren Codec.
• iChat: H.264/AVC.