Bits'n'Bytes

As heard on CJCD

Episode 40

Continuing with last weeks topic of acronyms, some of you may wonder what the difference is between an mp3, a wav file and a wma file. An mp3, or mpeg audio layer 3 file is a file which has had a lot of the data removed from it. The compression used removes anything the human ear wouldn't hear anyway, making the file about one twelfth the original size. Because of it's high quality and small size, it's one of the most convenient ways of transferring music over the internet.

The original file is usually a wav file - the type found on a CD. This is often a pure, uncompressed pcm or "pulse code modulation" file - which is the very first file created when converting an analog signal to a digital one. Because it's uncompressed, it can be a very large file and isn't really optimal for sending over the internet.

WMA files are Microsoft's equivalent to the mp3. The size of a wma file can be even smaller than an mp3, without losing any quality of sound. The difference is, special codes can be incorporated into a wma file. These codes can restrict playback without a certain licence key, can restrict playback based on the amount of time the file has existed or can add a key to be sure the file can only be played on the original computer that downloaded it.

Another popular download type is the avi movie. Avi, or audio/video interleave, is a file that is made of alternating sound and video, the two play together and alternate so quickly it looks and sounds like a movie. Because the audio part of an avi can be relatively uncompressed, a lot of avi files are quite large.

MPEG videos, based on the moving pictures experts group, come in a wide variety of formats. MPEG1 is for video CD's, MPEG2 is now used for HDTV and MPEG4 is now the standard for DVDs.

With all this downloading, stay tuned next week when I take a look at some antivirus programs.

I’m Computer Dave, thanks for your time.