97. Codecs key to playing media
By Andrew D. Wright
Your friend gives you a CD with video on it from his vacation. You pop it
into your computer, double click on the file name and when it opens up you
can hear the sound but there's no picture.
That's funny, you've played movie files with a .AVI file type before and
they've worked fine. What's going wrong is you don't have the right video
A codec is a way to COmpress and DECompress or COde and DECode
information, in this case the video information in the .AVI file.
The .AVI video file format is not one kind of file, it's what is called a
container format. It's a way of holding data in a form many different
programs and platforms can understand. That data, the video and sound
portions of the movie, can be encoded using any one of several different
codecs. The player must have the same codec or a compatible one to be able
to properly play the file.
DivX is the best known video codec. It's a proprietary format that offers
excellent picture quality with a greatly reduced file size. In wide usage
since 1998, these days many set-top DVD players can play DivX files, which
can have a .AVI or .DIVX filename.
Xvid is an Open Source video codec in wide usage. It's the main
competition to DivX (try spelling Xvid backwards) and like DivX is a
variation on the MPEG-4 Part 2 standard for encoding video. Because of
possible patent issues in the U.S. and Japan, the Xvid codec pre-compiled
for Windows is not available from the Xvid site directly but there is a
link to one made by a third party.
The combination of the right codec and right media player can add many
features to a video file such as subtitles, menus, and support for
advanced audio configuration items like 5.1 surround sound and multiple
languages. The quality of the picture and sound during playback can be
dramatically improved as well.
There are many media player programs available for download but for
Windows users it is hard to beat Media Player Classic. An Open Source
media player modelled after Microsoft's early Media Player 6.4, Media
Player Classic offers simplicity of use through its familiar interface
combined with a powerful feature set accessible through menus.
When combined with ffdshow, a popular encoder/decoder program, there are
few file formats Media Player Classic won't play. ffdshow adds support for
advanced video and audio processing during recording and playback for
improved picture and sound quality as well as support for a number of
different audio and video codecs.
While still in very wide use, the .AVI container file format is starting
to be replaced by others offering more features and smaller file sizes.
Videos can be .MP4 files, .OGG files, .MKV files and .3GP files among
other more widely known container file formats such as Apple Quicktime's
.MOV file type or a DVD's .VOB files.
Media Player Classic (free): http://sourceforge.net/projects/guliverkli/
ffdshow (free): http://sourceforge.net/projects/ffdshow-tryout/
Xvid (free): http://www.xvid.org/
DivX (free and shareware): http://www.divx.com/
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Originally published 3 December 2006