This doesn't have to cost you anything, as there are a host of excellent freeware tools that provide all the functionality you'll ever need - and we've uncovered five of the very best.
SUPER (the Simplified Universal Player Encoder & Renderer) uses several open-source tools to support a huge array of file conversion functionality.
The program is able to import all the main video formats, of course: 3GP, 3G2, AMV, ASF, DAT, DVR-MS, FLI, FLC, FLV, M2TS, MPG, MKV, MOV, M4V, NSV, OGM, QT, RM(VB), STR, SWF, TS, TRP, TY, TY+, TMF, VIV, VOB and WMV.
But SUPER can also record streaming internet videos. It's able to import sequences of images. And there's excellent support for audio file formats, too.
Output options include all the main PC video and audio formats, and the program also supports creating 3GP and 3G2 files for mobile phones, along with clips for the iPod or iPhone, Sony PS3 and PSP, Nintendo DS, Microsoft Zune, and more.
Figuring out how to do all this can take a while, as SUPER's interface comes packed with complex options. It's worth investing the time, though, because once you're familiar with how SUPER works then you'll be prepared for just about any file format conversion task.
2. Format Factory
Format Factory has a good list of output formats, being able to convert almost any video to MP4, AVI, 3GP, RMVB, WMV, MKV, MPG, VOB, MOV, FLV or even SWF files.
The program comes with a huge selection of device presets, too. So if you're not quite sure how your video should be configured, just choose the "All to Mobile Device" option and you'll find built-in settings for the iPhone, iPod and iPad; Sony PSP and PS3; Xbox 360; Microsoft Zune; and mobiles and other devices from companies like Archos, ASUS, Creative, HTC, iRiver, LG, Nokia, Philips, BlackBerry, Samsung, Sony Ericsson and more.
That's just the start, though. Format Factory can also convert audio files and images, join videos and audio files together, repair corrupted video files, rip CDs and DVDs, create ISO images - there are useful capabilities everywhere you look.
The program is a little buggy, crashing a few times in our tests. But if you can avoid these traps then Format Factory is effective, and fairly easy to use. Drag and drop a file, choose an output format and settings, and the program will usually be creating your video in just a few clicks.
Handbrake started life as an open source DVD ripper, quickly converting the disc of your choice into a more convenient video file. The program no longer provides any means of decrypting commercial DVDs, but by way of compensation it can now import just about any video format, thanks to the inclusion of some libraries from the FFmpeg project.
Export options are rather more limited, however. You can convert to MP4, or MKV, and, well, that's it.
If all you need to do is create videos suitable for your iPod or iPhone (or anything else that requires those formats), though, Handbrake will prove an excellent choice. The program provides a lengthy list of advanced options to control the final results, for instance.
But if you prefer a simple life, then you can ignore all these and have the program working in seconds. Just specify the source and destination file names, choose one of the presets (iPod, say), then click Start, and watch as your movie is converted.
4. HAMSTER Free Video Converter
HAMSTER Free Video Converter is a well-designed conversion tool that manages to include plenty of powerful features, without compromising on ease of use.
Importing files is as easy as dragging and dropping, for instance. Batch file conversion is possible so you can drop as many files as you like, and all the usual formats are supported.
Videos may be exported as AVI, MPEG, WMV, FLV, 3GP or MP3 files (if you only need the audio). Or you can choose predefined formats that will work on particular devices: iPods, the iPad or iPhone, or hardware from BlackBerry, HTC, Nexus, Nokia, iRiver, Creative, Zune, Archos, Xbox, the PSP or PS3.
It's then easy to customise your movie by choosing a video or audio codec, setting your file resolution, deciding whether you want to deinterlace the video, and more. Your preferred settings can then be saved in a list of Favourites for easy recall later, before you launch the conversion with a click.
5. Miro Video Converter
While most conversion tools have focused on adding more and more features, Miro Video Converter has moved in the other direction, stripping away every setting and option to make the program as simple as it can possibly be.
The process starts by dragging and dropping your video onto Miro Video Converter (it can handle almost every format).
Next, you're able to choose your output type. There's specific support for the iPhone, iPad and various iPods, the Sony PSP and a range of Android phones. Or you can do a simple format conversion to an MP4, Ogg Theora or WebM video.
Finally, click Convert and the program will create a new video in the same folder as the source file (though with a new name, fortunately).
There's no scope for customising your movie in any way, then - you can't change the resolution, frame rate, bit rate or anything else. This makes the program extremely simple to use, though, so if you're put off by the more intimidating interfaces of our other tools then Miro Video Converter could be worth a look.