transcode is a text-console utility for video stream processing,
running on a platform that supports shared libraries and threads.
Decoding and encoding is done by loading modules that are responsible
for feeding transcode with raw video/audio streams (import modules)
and encoding the frames (export modules).

It supports elementary video and audio frame transformations,
including de-interlacing or fast resizing of video frames and loading
of external filters. A number of modules are included to enable
import of DVDs on-the-fly, MPEG elementary (ES) or program streams
(VOB), MPEG video, Digital Video (DV), YUV4MPEG streams, NuppelVideo
file format and raw or compressed (pass-through) video frames and
export modules for writing DivX;-), OpenDivX, DivX 4.xx or uncompressed
AVI files with MPEG, AC3 (pass-through) or PCM audio. Additional
export modules to write single frames (PPM) or YUV4MPEG streams are
available, as well as an interface import module to the avifile
library. It's modular concept is intended to provide flexibility
and easy user extensibility to include other video/audio codecs or
filetypes.

WWW: http://www.theorie.physik.uni-goettingen.de/~ostreich/transcode/