How Do I Know What Codec I Need?by Contributor
A codec is a computer program that is used to encode and decode videos and music files. It typically works with as part of your computer media player to allow it to play back files that are encoded using a particular codec. Every audio and video file is made with a codec; it keeps the file small, thus making it easier to play back. To determine the specific codec you need, you can either look at the properties of the file or use a separate program that determines it for you.
Manually Finding the Codec Info
Use your own operating system to find out what codec you need. Right click on the file you would like to open. Select "Properties" if you are on a PC, or "Get Info" if you are using a Mac. Click on the "Summary" tab. In the file description, it should show you both the audio format and the video compression. These are the codecs used to make the file. Users can download these codecs from official websites of the companies that created them. Popular codecs include Xvid, DivX and MPEG. Once downloaded, install the codec and open the file with the media player you normally use.
Using Third-Party Software
If you cannot determine the codec information from the file properties, or the file is still not playing after you installed the codec, you will need to use third-party software. Popular software includes GSpot and MediaInfo. GSpot is just for PC but MediaInfo is available for both PC and Mac. These programs determine what audio and video codecs are required to play files. Simply download one of the two programs, install it and then select the file for which would like to get the codec information. You will then need to download that codec as described above.
Another option is to either download an alternative media player that includes most codecs. The most popular alternative media player is VLC Media Player from VideoLAN. It is available for both PC and Mac. When you download and install the player, it also installs nearly every major codec you will need to play any audio or video file. Another program that does this is MPlayer.
A final option is to download a codec pack that should include the codec you need to play the specific file. PCWorld Magazine recommends the Windows Essentials Codec Pack from MediaCodec.org. It includes all the major codecs and allows you to install them to work with your current media player. For Mac, a similar pack is available from Perian that installs all the codecs to work with Quicktime Player.