FFmpeg is an indispensable tool for
working with
audio and video streams, but it can be challenging to learn to use well.
FFmpeg — The
Ultimate Guide, posted by Csaba Kopias, can help. “This guide
covers the ins and outs of FFmpeg starting with fundamental concepts and
moving to media transcoding and video and audio processing providing
practical examples along the way.“

Source: LWN.net – A useful guide to FFmpeg