Posted by Eeyore on 11/29/07 21:41

Richard Crowley wrote:

> "Don Pearce" wrote ...
> > Randy Yates wrote:
> >>However, the Lempel-Ziv algorithm is indeed a source coding algorithm
> >>and in that sense can be called a codec.
> >
> > And there, in a nutshell, is the problem with the definition. An audio
> > codec is something that does stuff with - specifically - audio. It
> > makes use of the qualities and features of audio to enable compression
> > that would not be valid for - eg - pictures or documents.
>
> I don't see the problem. We all regularly refer to an "MP3 file" or a
> "ZIP file". And it is understood by everyone that decoding an MP3
> file requires a MP3 codec, just as decoding a ZIP file requires a
> ZIP codec.
>
> A standalone application of an MP3 codec is called an "MP3
> Player" just as a standalone application of a ZIP codec is
> called "WinZip" (etc.). But note that there are also versions of
> both MP3 and ZIP codecs (and most others) that are just DLL
> files and usable internally by other applications.

There is a BIG difference however. A true CODEC operates in real time. Zipping
and unzipping files is however not a real time process.

Wikipedia also takes the view that codecs must be real time.
http://en.wikipedia.org/wiki/Codec
"A codec is a device or program capable of performing encoding and decoding on a
digital data stream or signal. "

Note 'data stream' or 'signal'. NOT file.

Graham

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