[SSSSSmokey]

Just a couple o' questions:

1. When I take data off a CD, it is totally digital. IE, the bits must be exact or the file won't work (most of the time). What makes audio so different?

2. I have the NEC 2500A DVD-burner. Does it really make a difference when I read non-scratched CDs? I don't know what you guys put your CDs through, but mine are all pretty smooth still

. So are these tests only about messed up discs or does this affect ALL discs?

 

[adhoc]

Quote:

Originally Posted by SSSSSmokey 1. When I take data off a CD, it is totally digital. IE, the bits must be exact or the file won't work (most of the time). What makes audio so different?

audio data (redbook standard) is stored in a vastly different way from data cd-roms (yellowbook standard).

basically to simplify it vastly:

the writing format for data cds have far more comprehensive error checking algorithms and data recovery methods inbuilt into them. these prevent the loss of data in most cases, since a loss of a single bit in, say, a zipped file, would be disastrous.

unfortunately for audio cds, since they have to be read and played back on the fly, such comprehensive (and hence complicated) preventive measures cannot be used for them.

 

[Glassman]

they can actually, but it takes a lot of disc space and when they were introducing redbook audio, they thought that those few unrecoverable errors won't be audible at all, the player just guesses a new value and mask the error so that listener doesn't notify anything.. but we want it perfect, without any guessed values, that's all..

 

[adhoc]

Quote:

Originally Posted by Glassman they can actually, but it takes a lot of disc space and when they were introducing redbook audio, they thought that those few unrecoverable errors won't be audible at all, the player just guesses a new value and mask the error so that listener doesn't notify anything.. but we want it perfect, without any guessed values, that's all..

actually, iirc, there are far more errors than you would guess from any cd player - the beauty of it all is that there are hardware filters in most cdps that remove the pops, clicks and buzzes that are unfortunately so present in non-eac computer extracted digital audio.

 

[Glassman]

there are three levels or errors, C1 errors, which are pretty common and found on any disc, recovered without losing any data on redbook as well as data CDs, then there are C2 errors in places, where C1 error recovery fail, those are recovered without losing any data, but that's only for data CDs, redbook CDs must mask those errors by interpolating the value, muting or such.. C3 errors are exclusively matter of data CDs, when they appear, the disc in unreadable in such place.. there's usually few to none C2 errors on clean discs..