If you need to convert a few audio or video files then you could try out a few freeware transcoders, do your best to avoid the adware, hope they support the formats and options you need.

Or you could just grab a copy of FFmpeg, the open-source media-processing powerhouse which is the engine behind most freeware converters, anyway.

The program is run from the command line, which means it’s not as convenient to use as the GUI competition. But don’t let that put you off entirely, because it doesn’t take long to learn the basics.

Take a look at this:

ffmpeg -i video.avi video.mp4

FFmpeg has a vast library of command line switches, but don’t panic – you can do a lot with just one or two

You can probably already guess what this means. Two files, the -i means the first is the input video, the second is the file we want to create, so we’re converting our AVI source to MP4.

Need a different destination format? Just change the final .mp4 extension to whatever you need. This doesn’t only work with videos, like .mov or .flv – you could use video.mp3 to extract the soundtrack, or video.gif to create an animated GIF. (The latter would be huge, so only try it on tiny source videos.)

While we’ve used an AVI source as an example, this doesn’t just work with videos. FFmpeg can also convert between audio types, or image formats. And as FFmpeg supports just about every audio and video type there is, that can be very helpful.

It’s not just about simple one to one conversions, either. Try these.

ffmpeg -i video.mov frame%d.jpg
ffmpeg -i StillImage.jpg -i music.mp3 myvideo.mp4

The first extracts and saves the frames from a video to a series of jpegs, while the second takes a still image, adds a soundtrack and saves the results to an MP4 video.

This isn’t going to be useful in every situation. If you just want to take two or three videos and convert them to something iPhone-friendly, then figuring out the right command line switches will take too long. Dragging and dropping them onto a GUI converter is probably the way to go.

But, if you’d like to automate conversions, maybe support more formats, take finer control of the destination files, then exploring FFmpeg could be a very good idea. It’s relatively easy to get started, and if you want to go further then there’s a lot of help around.