Conference napalm::commusic_v1

    What does the government have to do with it?
    
    I think Sony already has such a unit, but it is still too expensive
    for the hobbyist market.
        John Sauter

    I was under the impression that DAT used a different sampling rate
    than CDs so that data copies weren't possible. One would have to
    go the DAC-->ADC route.
    
    Edd

	It seems to me that with a small computer you could dump a CD, do a
little signal processing and spit out the corrected data at the right 'sampling'
rate to a DAT.  Doesn't sound like it'd be that big a deal, maybe an hour or so
on an Apple II. 

re .1	My understanding is that record companies and such are trying to get
the govmint to place restrictions on DAT's.  Namely, they want DAT's to include
a feature that would make them unable to copy directly (digitally) from CD's.
They had some news article on TV about a month ago on it.  I don't know about
the sample rate problem, but I understand also that an error-correction scheme
(probably similar to that of CD's) is employed and would suspect compatibility
with CD's.  I'm just going by what I've seen on TV and read at the stands
(I'm too cheap to buy my own - except for my KEYBOARD subscription). Anybody 
have any sources on possible CD/DAT compatibility?

    A friend of mine here at CXO already has a Sony 8mm video machine
    with PCM record/playback BUILT-IN. It cost him "a few hundred" bucks.
    It will record a bunch of stereo tracks, but will only play back
    one stereo track at a time. It several hours of recording time on
    one tape.
    
    It sounds like the ideal stereo mastering deck.
    
    Oh yeah, and it does video record/playback, too.
    
    Peter
    

    Even without direct (i.e., digital data stream) compatibility, DAT
    will make a pretty nice copy of a CD even if you go through the
    conversion process twice (CD digital -> analog -> DAT digital).
    
    Ain't it neat when new, superior technology is suppressed so the
    shoot-from-the-hip "next quarter's results are all that count"
    types can make a buck?  It's not like DAT was a surprise.
    Especially when they screw those of us who don't bootleg.
    
    len.
    

    Sony EV-S700U 8mm VCR
    PCM SPECS
    
    Sampling Freq.	31.5 khz
    Audio Freq.		20-15khz
    Dynamic Range	More than 88dB
    Wow & Flutter	Less than 0.005% RMS
             

    RE: .4
    To my understanding there isn't any known way to
    *digitally* convert from one sample rate to another.
               
    Timo (reading this conference first time after several months)

re -.1	Good point.  In my "blue sky" I was assuming some interpolation on the
part of the computer to do the cut and paste as well as to add/delete voices.
Given that you can stay in the digital realm and not go to analog, I figure
it should be possible to use some sort of peripheral controlled by the computer
to interface between two DAT's.  I'm assuming that the peripheral will be able
to generate any voices so that it can add, delete or alter them.  And, I'm 
assuming that reverb, delay, and mixing can be handles in a similar manner by 
this peripheral.  Even if the sampling rates were the same frequency, it might 
be nearly impossible to sync without some "keys" or "clicks" on the tape.  So, 
there would probably need to be keys/clicks inserted that could be removed from 
the final version.  Removal would probably require interpolation.  And, the 
peripheral would have to do some heavy interpolation to edit voices, all of 
which would be sync'd to the keys/clicks.  A problem I see that might get in 
the way of being able to edit with an indefinite number of passes would be 
accumulative errors from multiple layers of interpolation.  This might become 
the only real source of noise.  

Surely someone is already working on this!

    re:.whatever
    Gee, I didn't realize that the PCM sampling rate was that low...
    Oh well. I don't need another mastering deck, anyway 8^)
    
    Peter
    

    
    The January '87 issue of IEEE SPECTRUM printed a short article
    on the current state of DAT, and I thought you all would be interested.
    I've chopped the first couple of paragraphs because they just review
    things already said in this note.
    
    In a separate article they also mentioned *4mm* tape for portable
    camcorders...
    
    
    ----------------------------------------------------------------
    
    ... To alleviate this concern, the DAT format, as it is now
    designed, blocks direct copying from CDs - DAT samples at 
    48kHz and CDs at 44.1kHz. However, add-on adapters to convert
    the sampling rate could be developed. But the CD's signal would
    have to be converted to analog and then reconverted to digital.
    Some noise would be added in the process.
    
    [my note: There are digital "resampling" techniques, but to 
    my knowledge they are not done easily or cost-effectively
    in real time, and noise, in the form of quantization error, 
    would be induced also]

    The Record Industry Association of America [RIAA], based in NYC,
    is lobbying for federal legislation to mandate that DAT units
    incorporate copy-code scanners - chips that would recognize a
    copyrighted work and refuse to tape it.
    
    When the DAT standard was initially being developed, technical
    specifications were issued for two different implementations -
    R-DAT and S-DAT. Manufacturing problems for S-DAT products have
    yet to be solved, but the R-DAT format was finalized last spring,
    so the first wave of DAT units will use that format. In R-DAT, 
    rotary heads scan data diagonally at 2.46 megabits per second as
    a metal tape moves past; in S-DAT, a stationary head reads data
    on 22 parallel tracks at 2.4 megabits per second. [in other words,
    R-DAT is "like a VCR" and S-DAT is "like a standard cassette"]
   
    The R-DAT cassette measures 73mm x 54mm x 10.5mm
    [2.87" x 2.13" x .41", which makes it about an inch shorter 
    and the same thickness (as the "wide part") of the standard cassette].
    
    R-DAT recorders will probably sell for over $1000 initially.
    The cassettes can hold up to 2 hours of music, but most pre-recorded
    tapes are expected to run 80 minutes or less, which allows the
    use of cheaper tape. CDs are limited to approximately 75 minutes.

    ------------------------
    
    My opinion is that the R-DAT machines are simply not worth the hassle,
    and if all these infernal copy-protect machanisms are installed,
    the medium will die quickly. Which will leave the bean-counters with
    no money, instead of the moderately nice pile of money they could
    have had by not being so greedy.

    Therefore, I'm NOT putting any of this stuff on MY wish list!
    
    							Scot

    

This kind of addresses the "blue sky" from the original note.  After
    reading this I figure an ST is in my future.  BTW, Atari also announced
    2Mb and 4Mb versions of the ST I think in the $1500 ballpark:


Newsgroups: rec.music.synth,comp.sys.amiga,comp.sys.mac
Path: decwrl!ucbvax!ucbcad!ames!cit-vax!rgoodman
Subject: Re: Info on AMIGA vs. MAC+ vs. ATARI ST for use in a MIDI system
Posted: 23 Jan 87 14:49:46 GMT
Organization: California Institute of Technology
Xref: decwrl rec.music.synth:206 comp.sys.amiga:1644 comp.sys.mac:935
 
[]
 
I am surprised that no one has mentioned the Atari ST computer on this
network yet.  Considering it is the only computer (other than the crummy
Yamaha music computer) that has a built in MIDI interface, a fast 68000
microprocessor (at a higher clock speed than a Mac) and at a price that
makes a Mac or an Amiga seem absurd.  The 520ST I purchased with monitor
and disk drive and 1/2 Megabyte of memory cost $549.  Considering this
computer is better than all the others...  There is even a new emulator
to let an ST run Mac software.  Although I'm not sure, I believe it runs
the Mac software faster.  I have mine hooked up to a Mirage synthesizer
and find the combo to be dreamy.  I hooked up the two and was immediately
able to write my own MIDI software in BASIC and then in C.  I am now
writing a Visual Editing System for the two, and I don't think I can envision
a better programming environment - lot's of memory, high speed, super easy
access to MIDI.  Below is an interesting excerpt from the comp.sys.atari.st
board about a new product from a company all synth players should be familiar
with when adding a computer on.
 
-------------
 
 
     Permission to reprint or excerpt is granted only if the following lines
appear at the top of the article:
     ANTIC PUBLISHING INC., COPYRIGHT 1987.
     REPRINTED BY PERMISSION.
 
     Atari at The Winter 1987 CES
     Software and Wrap-up, Part 1.
 
. . . .
 
     12/Jan/1987
     Hybrid Arts Inc., the software and hardware with a reputation for putting
out the best MIDI software in the industry, showed one of the most exciting new
products in the Atari world:  The ADAP Soundrack.  ADAP stands for Analog to
Digital Processor.  It's a $2000 hardware plus software system, built in
conjunction with Nilford Laboratories, Inc., for the Atari ST, designed to
replace equipment costing over thirty times as much.  The basis of the ADAP is a
racey black rack mount box with sound input and output lines, plus an interface
box which plugs into the cartridge port of a one- (or more) megabyte machine.
What does it do?  Digital sampling.  And it does it well.
     Digital sampling is a process where sound is converted into digital
patterns which a computer can store, manipulate, and play back at will.  Compact
discs have been using this technology for years now.  Sound enters the ADAP box
from virtually any sound source (such as a compact disc player) and is converted
into digital signals in the ST's memory. Once the sound is in the ST, it appears
as a digital waveform in a window in the center of the screen.
     You can examine the waveform by zooming in or out on either the X or Y
axis, or even both.  You can scroll along the waveform to see its entirety, or
even sample more than one sound and switch between them.
     Hybrid Arts claims the system can sample at a rate of 44.1 Khz with 16 bits
of resolution -- that's compact disc quality!  It even samples in stereo.  Once
a sample is made, it can be played back at the push of a button.  The sound is
phenomenal.  But ADAP doesn't just let you record samples. You can also edit
them.  You can cut, copy, and paste portions of a sample.  You can even do
mixing, looping, or modify the actual waveform freehand.
     The ADAP system replaces some super-sophisticated musical sampling
equipment by allowing you to "play" the samples from your MIDI keyboard,
polyphonically, with up to eight voices going simultaneously.
     - On a one-megabyte machine, allows 80 seconds of sampling at full 16-bit
linear resolution at 10 Khz.  Allows 20 seconds at 44.1 Khz.
     - Fully MIDI compatible
     - Polyphonic
     - Storage of up to 64 multi-samples in memory for instant playback.
     - Real-time digital effects processing (delay, echo, reverb, etc.)
     - Real-time oscilloscope
     - Direct from compact disc, digital to digital sampling.
     - Multi-sample keyboard splits.
     - Compatible with the new MIDI digital sample dump data standard.  Will
work with data from other MIDI sampling devices.
     - 19" black rack-mount case.
     - Suggested retail price is $1,995.
     When asked why they chose the Atari ST as the host sytem, Frank Foster,
president of Hybrid Arts, replied: "It's not like we actually 'chose' Atari.  It
simply couldn't be done on any other machine.  Not on an Amiga.  Not on a
Macintosh."  Now that's a compliment.
 
. . . .
 
So be sure not to overlook what is certainly the least expensive and probably
the best option you have available at this time in the way of computers.
 
Ron Goodman
------------------------------------------------------------------------
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    Like most Atari hype, this posting's intro took a lot of heat from
    the USEnet.  Also, the product announcement's assertion that "it
    couldn't be done on any other machine" is pure BS.
         
    len.