Looking for utility to save a frame as a jpeg

[Peter K]

I know this is a bit off-topic but does anyone know of a command-line utility to allow me to go into an mpeg file and extra a specific frame as a jpeg image?

I'm looking for something where I can pass it the filename of the mpeg file, a time or even a frame number and it will spit out a jpeg file for me to use. The thing is, it has to be completely command-line driven -- a GUI won't do here.

I've written a simple post-processing batch file that lets me know of the completion of recordings via e-mail while I'm away for extended periods of time. it would be cool to get a frame or two of jpeg from the video for no other reason than it would be neat.

Thanks,
--Peter