ffmpeg - audio/video encoder, streaming server & audio/video file converter

Description:
audio/video encoder, streaming server & audio/video file converter. ffmpeg is a hyper fast real time audio/video encoder, a streaming server and a generic audio and video file converter.

It can grab from a standard Video4Linux video source and convert it into several file formats based on DCT/motion compensation encoding. Sound is compressed in MPEG audio layer 2 or using an AC3 compatible stream.
And another description of it:
This package contains the ffplay multimedia player, the ffserver streaming server and the ffmpeg audio and video encoder. They support most existing file formats (AVI, MPEG, OGG, Matroska, ASF, ...) and encoding formats (MPEG, DivX, MPEG4, AC3, DV, ...)
[greg@duke:pdfs]$ apt-cache policy ffmpeg\nffmpeg:\n  Installed: 3:20050806-0.2\n  Candidate: 3:20050806-0.2\n  Version table:\n *** 3:20050806-0.2 0\n        990 ftp://ftp.nerim.net sid/main Packages\n        100 /var/lib/dpkg/status\n     0.cvs20050918-3 0\n        990 http://paladin.gregfolkert.net unstable/main Packages\n        990 http://ftp.us.debian.org unstable/main Packages