From: 2575brooksr@vms.csd.mu.edu (Ryan K. Brooks)
Newsgroups: comp.sys.amiga.misc
Subject: Re: Reasons for Amiga CD
Date: 28 Jan 1993 04:55:51 GMT
Organization: Marquette University - Computer Services
Distribution: world
Reply-To: 2575brooksr@vms.csd.mu.edu
NNTP-Posting-Host: vmsa.csd.mu.edu

In article <Paula_Lieberman.07xi@amicol.UUCP>, Paula_Lieberman@amicol.UUCP (Paula Lieberman) writes:
>In a message dated Fri 16 Jan 93  0:57, 2575brooksr@vms.csd.mu.edu (ryan K.
>wrote:
>
> K> Message-ID: <009669AC.760C3000@vms.csd.mu.edu>
> K> Date: 14 Jan 93 21:53:05 GMT
> K> Paula_Lieberman@amicol.UUCP 
> K> The reason they are "deliberately lossy" is only because the media
> K> chosen
> K> to store the audio data is much smaller (bit-wise) than is required to
> K> store
> K> a 100% representation of the sound.  MD and DCC wouldn't be so "Mini"
> K> and 
> K> "Compact" if they weren't lossy. 
>
>Uh-uh, the data capacity either would be lower, or the price higher to
>provide denser storage.
>>Um, getting back to the start of that meandering sentence:  DCC and
>>minidisk both do not keep full 16 bit, 0 - 48 kHz data; some of the
>>frequencies get ditched, to reduce the data processing throughput load,
>>among other things. 
>
> K> Neither format throws frequencies away, that would sound very odd.
>They >compress< the data.  Simply put, certain aspects of the overall
> K> waveform are not recorded to disk/tape.  Not good for high-end stuff.
> K> But
> K> try listening to the same stuff off of CD and a MD/DCC copy, I
> K> couldn't
> K> tell the difference, and I doubt 90% of the people out there can.
>
>a) I've run into a fair number of people who -can- tell the difference, who
>still have the high ends of their hearing intact (go to too many LOUD rock
>concerts, and the HF hearing response dies.  Jet pilots often have
>-notches- in their hearing at engine whine frequencies.  Etc.
>
>b) The DEFINITION of "lossy" is losing data.  The compression that MiniDisk
>and DCC use BOTH removes high frequency date -- uh, do you know anything
>about stuff like  Fourier Transformer, Laplace Transforms, Fast Fourier
>Transforms, Discrete Cosine Transforms, etc., that convert between time and
>frequency domains?  The -loss- in -lossy- compression using such techniques
>deletes frequency domain data..... 
>

Actually I do know about transforms, I'm EE.  What you said is that it
"throws" away certain freqs, and this is not the case.  A transform
just isn't as accurate as real world data.  Let's say it approximates
the data.
 
>>So, both formats technically are inferior to DAT.
>
> K> DCC is very similar to DAT.  MD offers fast random access without any 
> K> tape-wear. The ONLY way that they are inferior is the lossy
>And lossy stor  storage is INFERIOR in quality to lossless storage.  Sigh.
> K> compression.
>
>>Throwing away digital signal information also means that neither DCC nor
>>MiniDisc is appropriate as a data storage format..... just think, you go
>to
>>retrieve a file, and there's data -deliberately- missing!
>>
>
> K> Bzzzzzzt! Try again.  Both formats store a PERFECT image of digital
                                                 ^^^^^^^^^^^^^^^^^^
> K> information.  The process that both Sony and Phillips chose for
   ^^^^^^^^^  I am saying the digital storage format is not lossy-
that wouldn't make sense.  I am NOT saying the way music is digitized
on MD/DCC isn't lossy.
> K> encoding
> K> music loses some information but  this compressed "image" is stored 
> K> perfectly to disk/tape.   Both formats would store computer data
> K> pefectly.
>
><screech -- the very STORAGE algorithm is lossy, it's BUILT in! 

No its not.

	Playback
	
	Stream->Buffer->Decomp->D/A

	Record

	A/D->Comp->Buffer->Stream

The AUDIO data is digitized, then PROCESSED, then stored.  The data on
the disk hasn't lost anything at any point after the compression.

 Computer data would be stored just like the POST-compression audio data.   
No loss occurs.  

	So, TO SUM IT UP, MD or DCC would work perfectly for computer use.
You'll never see DCC in a computer, but I wouldn't be surprised if MD
pops up... access times are slow since the optical assembly is rather heavy,
but it ought to be be faster than a CD-ROM.

>                         
>-- Via DLG Pro v0.992
>
 ----------------------------
 Ryan K. Brooks                Chip of the Month Club: TMS320C40
 2575BrooksR@vms.csd.mu.edu
Newsgroups: comp.sys.amiga.misc