ken@birtch.UUCP (Ken Brown x254) (10/03/85)
I don't know if it is true, but my roomate has informed me that the manu- facturers of CD's introduce white noise (maybe pink noise) to reduce the 'spikes'. CD's will produce a "stair-step" type of waveform, and the white (pink) noise produces a flat line (or curve), instead of spikes. disclaimer: I don't know if its true or just B.S. (I don't work for no-one who makes, designs, sells, uses, borrows, steals, or thinks about CD's)
prk@charm.UUCP (Paul Kolodner) (10/08/85)
> I don't know if it is true, but my roomate has informed me that the manu- > facturers of CD's introduce white noise (maybe pink noise) to reduce the > 'spikes'. CD's will produce a "stair-step" type of waveform, and the > white (pink) noise produces a flat line (or curve), instead of spikes. > > disclaimer: I don't know if its true or just B.S. (I don't work for no-one > who makes, designs, sells, uses, borrows, steals, or thinks > about CD's) This is pure, smooth bullshit. Erase it from your memory and get a new roommate.
ark@alice.UucP (Andrew Koenig) (10/09/85)
>> I don't know if it is true, but my roomate has informed me that the manu- >> facturers of CD's introduce white noise (maybe pink noise) to reduce the >> 'spikes'. CD's will produce a "stair-step" type of waveform, and the >> white (pink) noise produces a flat line (or curve), instead of spikes. >> > This is pure, smooth bullshit. Erase it from your memory and get a > new roommate. Sorry, but the roommate is correct. The process of adding noise to eliminate distortion caused by sampling is called "dithering." I am told that it is essential -- if it is not done, the sampling effects are audible. It is for that reason that the highs, especially things like cymbals, sound slightly strange in many earlier CD recordings (I have trouble hearing that effect myself, but I know people who can detect it instantly and reliably).
herbie@polaris.UUCP (Herb Chong) (10/13/85)
In article <148@birtch.UUCP> ken@birtch.UUCP (Ken Brown x254) writes: >I don't know if it is true, but my roomate has informed me that the manu- >facturers of CD's introduce white noise (maybe pink noise) to reduce the >'spikes'. CD's will produce a "stair-step" type of waveform, and the >white (pink) noise produces a flat line (or curve), instead of spikes. > >disclaimer: I don't know if its true or just B.S. (I don't work for no-one > who makes, designs, sells, uses, borrows, steals, or thinks > about CD's) this is known as dithering and there are few CD players these days that don't use it. the overall S/N is reduced, but the quantization noise at low levels is randomized so that subharmonics of the sampling frequency are not audible. Herb Chong... I'm still user-friendly -- I don't byte, I nybble.... New net address -- VNET,BITNET,NETNORTH,EARN: HERBIE AT YKTVMH UUCP: {allegra|cbosgd|cmcl2|decvax|ihnp4|seismo}!philabs!polaris!herbie CSNET: herbie.yktvmh@ibm-sj.csnet ARPA: herbie.yktvmh.ibm-sj.csnet@csnet-relay.arpa
rfg@hound.UUCP (R.GRANTGES) (10/17/85)
[] Re:dithering Isn't dithering done by white noise in the encoding process? If added at the decoding process you just get simple masking - which also helps. -- "It's the thought, if any, that counts!" Dick Grantges hound!rfg
schley@mmm.UUCP (Steve Schley) (10/17/85)
In article <193@polaris.UUCP> herbie@polaris.UUCP (Herb Chong) writes: >In article <148@birtch.UUCP> ken@birtch.UUCP (Ken Brown x254) writes: >>I don't know if it is true, but my roomate has informed me that the manu- >>facturers of CD's introduce white noise (maybe pink noise) to reduce the >>'spikes'. CD's will produce a "stair-step" type of waveform, and the >>white (pink) noise produces a flat line (or curve), instead of spikes. >this is known as dithering and there are few CD players these days >that don't use it. the overall S/N is reduced, but the quantization >noise at low levels is randomized so that subharmonics of the sampling >frequency are not audible. To the best of my knowledge, there are few CD players that DO use dithering at playback. I think Ken meant that the manufacturers of the DISCS were incorporating white noise, and some are. Such dithering does just what Herb claimed for it. For those who want to know more about dither: check the last year of issues of the Journal of the Audio Engineering Society. Lipschitz and Vanderkooy published a treatise on the application of dither in audio analog-to-digital conversion. My study of this article leads me to think that dither is appropriate for analog-to-digital conversion, but inappropriate for digital-to-analog conversion. If anyone understands these issues and would like to comment on them, I'd like to hear from you (preferably by mail). I'm trying to decide whether adding dither to my CD player will likely improve its sound. -- Steve Schley ihnp4!mmm!schley