I recently was doing some work with some videos. Things were working just fine at one point, but then I installed the latest version of JRiver Media Center (version 13).

Whammo. My videos wouldn’t play anymore. Well, actually, they’d play audio, but the video was just black.

I thought it was the particular app I was using, so I tried Media Center, and Microsoft’s Media Player. Same result.

From past experiences, I figured something had hosed a codec (codecs are utility libraries installed on your machine that code and decode video and audio files, each format has it’s own codec).

But, where to start looking?

So, I did some googling and found a great page that lists all the various FOURCC codes for codecs:

http://www.fourcc.org/fcccodec.htm

From that, I found a little app you run against a specific AVI to determine what codec it uses, called GSPOT:

http://www.headbands.com/gspot/v26x/index.htm

Running that against the AVI in question yielded the XVID codec.

Alternatively, just view the AVI in a hex editor and look at the header in the file:

You should be able to pick out the four character CC code fairly readily.

Then, from the table at FOURCC, I went to the xvid codec page:
http://www.xvidmovies.com/codec/
Downloaded and installed. Presto! Videos with audio and video again!

It’s just that simple 🙂