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Re: CDs, was DATs, Was Re: arsclist Duplicating casette tapes

At 10:49 AM 8/10/2002 -0700, Richard L. Hess wrote:
When the AUDIO CD was introduced in whatever year at the AES, I recall SONY marketing people using electric drills to randomly drill 1/8 inch (~3mm) holes in CDs and showing how well they played.

The "thing" that I've heard is that CD-ROM drives have one less layer of audio error CORRECTION than Audio CD players, but yet I've also heard that DATA is more robust than AUDIO.

Informal experiments have borne this out. Perhaps I heard incorrectly and the process that is missing from CDROM drives (even when playing audio discs) is error CONCEALMENT.

I would appreciate it if you could take some time and explain the layers of CORRECTION and (obviously CONCEALMENT for audio only) that are available on the CD and the DVD. I say the latter because people make claims that the error CORRECTION on the DVD is 10X better than the CD.

No doubt, Jerry will correct me when he has the opportunity, but you are conflating two issues.

1. There is one layer of error correction applied to data discs (Mode 1 or Mode 2, Form1) which is not used for CD-DA (audio) or for Mode 2 Form 2 (VCD). Eliminating that substantial protection permits an additional 12% or so of recording time; the tradeoff is against increased probability of error.

2. In playback for analogue output, every CD drive applies error concealment to make up for missing or erroneous audio data. That interpolation does not apply to DAE - digital audio extraction.



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