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pedalvet
2006-03-06, 20:33
Something occured to me today. Most of us take great care to set up EAC properly, use Accurate Rip etc, to make sure we get perfect rips. What happens when you transfer FLACs from one drive to another? Is there any assurance that errors are not introduced?

crooner
2006-03-06, 20:45
Once you rip the CD to the computer medium all subsequent copies and transfers are bit perfect. This is so because digital data in computers is either good or corrupted. The operating system makes sure the file integrity is preserved.

EAC is needed because audio CDs are derived from the 1980 "red book" audio standard. The data is handled as "audio" material and hence the integrity of the information is not always assured. If there's an error in the data stream, the system interpolates the missing bits. The resulting stream will not be accurate.

In computer terms this would not be acceptable since data errors will cause programs to crash or not work properly, but for audio the designers (Philips and Sony) thought it wouldn't be perceptible.

In reality, too much data interpolation (resulting from scratched CDs) will result in thin, grainy and harsh sound reproduction, aside from the obvious skips that can occur.

EAC will do its best to extract the correct bits from the CD. It will re-read the information several times, if needed, to ensure an accurate rip.

Also, a severely scratched CD will never be accurately ripped by EAC. EAC is effective for CDs in good physical condition.

pfarrell
2006-03-06, 20:49
pedalvet wrote:
> Something occured to me today. Most of us take great care to set up EAC
> properly, use Accurate Rip etc, to make sure we get perfect rips. What
> happens when you transfer FLACs from one drive to another? Is there
> any assurance that errors are not introduced?

A flac file is a computer file.
If you worry about data integrity while copying and/or moving the
file, you can use the usual tools. Most people
simply trust that the operating system is capabile
of copying a file properly. It is a fundamental
function that any operating system has to be able to do.

The simplest is to calculate a checksum of the file's contents.
A simple CRC-16 is good enough, or you can use a cryptographic
hash.

What tool you want to use depends on your Operating system,
whether you want a GUI or a shell utility, etc.

--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

pedalvet
2006-03-07, 09:59
Thanks for the responses!