paljug@grip.cis.upenn.edu (Eric Paljug) (03/19/90)
In article <2486@rodan.acs.syr.edu> amichiel@rodan.acs.syr.edu (Allen J Michielsen) writes: >3. If you think CD's are bad, DAT has a 45DB NOTCH cut in it at 15KHZ, that is > about 1K wide above 3DB. I find this offensive cut worse than anything > cd's could do. In article <6296@blake.acs.washington.edu> wiml@blake.acs.washington.edu (William Lewis) writes: > I seem to remember this being some sort of bizarre copy protection >scheme -- the DAT will refuse to record unless there are frequencies >in this notch, and commercial stuff will be distributed with those >frequencies cut out. It sounds too stupid to be true, but I've heard this >several places (now including the net). Real flat response, uh huh ... Didn't this go before a congressional committee a year or so ago and the committee found that the notch filter altered the product so much that it was unacceptable? In fact, I thought this ruling (combined with SONY buying the record company who was making the case for the prevention of recording commercial products) basically ended the record industry's attempt at preventing the recording of commercial stuff. I didn't follow this stuff too closely but I think the above is accurate. Corrections are welcome! Eric Paljug paljug@grip.cis.upenn.edu
wte@sauron.Columbia.NCR.COM (Bill Eason) (03/20/90)
In article <21875@netnews.upenn.edu> paljug@grip.cis.upenn.edu (Eric Paljug) writes: >In article <2486@rodan.acs.syr.edu> amichiel@rodan.acs.syr.edu (Allen J Michielsen) writes: >>3. If you think CD's are bad, DAT has a 45DB NOTCH cut in it at 15KHZ, that is >> about 1K wide above 3DB. >In article <6296@blake.acs.washington.edu> wiml@blake.acs.washington.edu >(William Lewis) writes: >> I seem to remember this being some sort of bizarre copy protection >>scheme -- the DAT will refuse to record unless there are frequencies >>in this notch, and commercial stuff will be distributed with those >>frequencies cut out. It sounds too stupid to be true, but I've heard this >>several places (now including the net). Real flat response, uh huh ... >Didn't this go before a congressional committee a year or so ago and the >committee found that the notch filter altered the product so much that it was >unacceptable? In fact, I thought this ruling (combined with SONY buying >the record company who was making the case for the prevention of recording >commercial products) basically ended the record industry's attempt at >preventing the recording of commercial stuff. I remember reading about the notch method a while back. The exact frequency chosen was supposed to be halfway between two notes, say, high A-flat and high A. That way, it was proposed, it would be a frequency that was never used anyway, right? Wrong. This scheme was apparently devised by someone with little knowledge of music, harmonics, or filters. The arguments I remember best are: 1) The piano and some other instruments may, in theory, only be able to play certain notes, but the voice can slide anywhere between notes. Notes are just like points of reference on a continuous scale. 2) The same is true for synthesizers, slide trombones, guitars (bending strings), "wailing" saxophone, trumpet, etc, etc .... 3) Finally, all of the above examples deal only with the fundamental frequency of the note being played by *whatever* instrument. They say nothing about the harmonics above the fundamental which can easily fall between "notes" on the scale. It is the harmonics that give each instrument its own personality. I find it hard to believe that those so in the industry even let such a ludicrous proposal get as far as it did. Kinda scary, huh? -- Bill Eason (803) 791-6348 ...bill.eason@ncrcae.Columbia.NCR.COM NCR Corporation E&M Columbia 3325 Platt Springs Road West Columbia, SC 29169