Posted by Don Pearce on 11/29/07 17:43

On Thu, 29 Nov 2007 12:37:31 -0500, Randy Yates <yates@ieee.org>
wrote:

>nospam@nospam.com (Don Pearce) writes:
>
>> On Thu, 29 Nov 2007 11:50:28 -0500, Randy Yates <yates@ieee.org>
>> wrote:
>>
>>>nospam@nospam.com (Don Pearce) writes:
>>>
>>>> On Thu, 29 Nov 2007 11:42:21 -0500, Randy Yates <yates@ieee.org>
>>>> wrote:
>>>>
>>>>>nospam@nospam.com (Don Pearce) writes:
>>>>>
>>>>>> On Thu, 29 Nov 2007 13:09:22 +0000, Eeyore
>>>>>> <rabbitsfriendsandrelations@hotmail.com> wrote:
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>Randy Yates wrote:
>>>>>>>
>>>>>>>> Eeyore <rabbitsfriendsandrelations@hotmail.com> writes:
>>>>>>>> > [...]
>>>>>>>> > ALL audio compression schemes rely on 'throwing away' information to get the
>>>>>>>> > desired result.
>>>>>>>>
>>>>>>>> I suppose you meant to say "ALL lossy audio compression schemes ...".
>>>>>>>
>>>>>>>Fair enough.
>>>>>>>
>>>>>>>How much data compression can the non-lossy ones deliver ? I've never investigated. I imagine
>>>>>>>it can't be that much.
>>>>>>>
>>>>>>>Graham
>>>>>>
>>>>>> I don't think the non-lossy ones are strictly codecs - just data
>>>>>> compression and restoration systems.
>>>>>
>>>>>Lossless data compression is formally a type of "source coding," so
>>>>>codec (meaning "coder/decoder") is a perfectly accurate term for the
>>>>>process.
>>>>>
>>>>>A/D conversion is a type of quantization, which also falls under the
>>>>>classification of source coding, so the application of codec is accurate
>>>>>in this sense as well.
>>>>
>>>> Sure, I know all that; but that is kind of against the spirit of the
>>>> word.
>>>
>>>How so?
>>
>> Because, as Graham has pointed out, under that terminology a Zip file
>> would be a codec, and that isn't really what codecs are all about.
>
>A zip file is a file. It isn't a codec any more than an mp3 file is a
>codec.
>
Don't split hairs - you know what I mean.

>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.

d




--
Pearce Consulting
http://www.pearce.uk.com

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