[Table of Contents]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: arsclist cylinder frequency range

Date sent:      	Thu, 17 Jan 2002 10:36:55 -0800
To:             	ARSCLIST@xxxxxxxxxxxxxxxx
From:           	David Seubert <seubert@xxxxxxxxxxxxxxxx>
Subject:        	Re: arsclist cylinder frequency range
Send reply to:  	ARSCLIST@xxxxxxxxxxxxxxxx


you wrote....

 when compressing files using Quicktime that
> the less noise in the source, the better the compression works.

----- in which way better? - we need a terminology here. 
Compression is usually loss-less. Data reduction is not. 
Physiological data reduction (my, hopefully more precise, term for 
"psychoacoustic data reduction") actively removes that which 
might be unheard anyway by average humans because of various 
types of masking. Subsequent spectral correction may then call for 
signal components which are no longer there. "better working 
compression" might mean "enables really low data rates" or "does 
not sound too artificial", if we are really talking data reduction. At 
any rate, trying to apply signal processing to a retrieved data-
reduced signal, in particular where the S/N ratio is low, really 
creates trouble.

> the amount of noise in a cylinder, we are going to have to use some
> sort of low pass filter or the compressed files will sound terrible.

----- I do not think that low-pass filtering is a good thing. In the 
LINEAR world I would propose using a wide frequency range for 
distribution, because low pass filtering is so simple that an end-
user can apply it to his or her own taste. Distributing a low-pass 
filtered signal is distributing a mutilated signal. In a data reduced 
world I appreciate that there would be a need for a different 

> We haven't yet decided what frequency the low pass filter should be
> at. When our tests are done, results will be posted on our website.

----- here I would support Joe Salerno's idea that you might put 
something semi-manufactured on the net. If the ARSClist is not 
suitable for hefty files, then perhaps you could put it on a server, 
password "ARSClist".

Kind regards,

Preservation Tactics

For subscription instructions, see the ARSC home page
Copyright of individual posting is owned by the author of the posting and
permission to re-transmit or publish a post must be secured
from the author of the post.

[Subject index] [Index for current month] [Table of Contents]