What Is a Codec and Why Do I Need It?

What Codecs Are And How They're Used

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A codec, a blend of the words code and decode, is a computer program that can use compression to shrink a large movie file, or convert between analog and digital sound.

You might see the word used when talking about audio codecs or video codecs.

Why Codecs Are Required

Video and music files are large, which means they are usually difficult to quickly transfer them over the internet. To help speed up downloads, mathematical codecs were built to encode, or shrink, a signal for transmission and then decode it for viewing or editing.

Without codecs, downloads would take three to five times longer than they do now.

How Many Codecs Do I Need?

Sadly, there are hundreds of codecs being used on the internet, and you will need combinations that specifically play your files.

There are codecs for audio and video compression, for streaming media over the internet, speech, videoconferencing, playing MP3s, or screen capture.

To make matters more confusing, some people who share their files on the web choose to use very obscure codecs to shrink their files. This makes it very frustrating for users who download these files, but do not know which codecs to get to play them.

If you're a regular downloader, you'll probably need ten to twelve codecs to play all the different types of music and movies you have.

Common Codecs

Some codec examples are MP3, WMA, RealVideo, RealAudio, DivX and XviD, but there are many other obscure codecs.

AVI, though a common file extension you see attached to lots of video files, is not in itself a codec but instead is a common "container format" that many different codecs can use. Because there are hundreds of codecs out there that are compatible with AVI content, it can get very confusing which codec(s) you will need to play your video files.

How Do I Know Which Codec to Download/Install?

Since there are so many codec choices, the easiest thing to do is download "codec packs". These are collections of codecs gathered in single files. There is much debate over whether it is necessary to get a large group of codec files, but it certainly is the easiest and least-frustrating option for new downloaders. 

Here are the codec packs you are the most likely to need:

  1. CCCP Combined Community Codec Pack is one of the most comprehensive codec packages you can download. CCCP was put together by users who like to share and watch movies online, and the codecs they've chosen are designed for 99% of the video formats you will experience as a P2P downloader. Definitely consider CCCP if you think your computer needs updated codecs.
  2. XP Codec Pack XP Codec Pack is a sleek, all-in-one, spyware/adware free codec collection that's isn't too large in size, so it shouldn't take long to download. XP Codec Pack is truly one of the most complete assemblies of codecs needed to play all major audio and video formats.
  3. K-Lite Codec Pack Very well tested, K-Lite Codec Pack is loaded with goodies. It lets you play all the popular movie formats. K-Lite comes in 4 flavors: Basic, Standard, Full and Mega. If all you need is to be able to play DivX and XviD formats, Basic will do just fine. Standard pack is probably the most popular - it has everything an average user needs to play the most common file formats. Full pack, designed for power users, has even more codecs in addition to encoding support.
  1. K-Lite Mega Codec Pack Mega is a very comprehensive bundle...it has everything but a kitchen sink. Mega even contains Media Player Classic.

If you use Windows Media Player, it will often try to communicate to you the 4-character code of the specific codec it needs. Note this code and then visit FOURCC to obtain the missing codec. FOURCC's Samples page has some FAQs if you need more information on what's offered there.

Another option for getting codecs is to download media players that include them. Sometimes, a video/audio player will install important and common codecs when you first install the application. VLC is a great free media player that can play all sorts of file types.