How to play any video file

Watching online videos and movie files from other sources is not always as simple as it should be. There are dozens of different formats and an equally confusing array of media players to go with them.

So, how do you make sure that all the various files and formats you encounter play back smoothly on your PC? Read on to find out.

Video compression
If you have ever tried to watch a video on a website or play a downloaded movie file only to be greeted with no sound, no picture or nothing at all except for an incomprehensible error message, don’t worry, you are not the only one.

The trouble is there are many types of video file that require different software to play. And the reason there are so many different formats comes down to one thing: size.

Video files are, by their nature, large and, in order to distribute them online or store them economically on a hard disk they need to be made smaller somehow.

To get an idea, video is usually made up of 25 frames per second. That is the equivalent of 25 medium-resolution photos every second, plus sound.

Storing this as a digital file in its raw form would add up to a huge amount of data – up to 2GB per minute – that would make keeping anything other than a few short clips on your PC impractical and watching video online would be impossible, even with the fastest broadband connection. Thankfully, compression can help.

Compression is a technique used to squash files down to a fraction of their size. Usually, this means losing a certain amount of data. In terms of video compression, this usually works by first losing data that the human eye might not normally see.

It's similar to the way MP3 compression can squeeze a song down to a tenth of its original size by omitting frequencies beyond the range of human hearing. Even DVDs use video compression. In order to fit a film onto a 4.7 or 8.5GB double-layered DVD disc, for instance, a type of compression called MPEG2 is used.

High-definition video is compressed too – indeed, compression is even more important when each frame of video contains up to seven times more information than standard definition.

To deliver video effectively over the internet, file sizes need to be even smaller, so even more powerful compression is usually used.

Unfortunately, there’s no single, unified video compression technique, which means that, over the years, a wide range of different video formats have evolved. This means you will need a selection of software on your PC in order to play back the various video formats.