AccurateRip checks the 32-bit CRC of what you ripped against what others
have reported on a track-by-track basis.  The metadata (tags) are not
ripped from the CD, but usually obtained from an online database like
freedb.

In order for the CRC to match AccurateRip, it is best not only to use
secure data extraction mode, but to use the proper secure gap-detection
algorithm so that the file size matches exactly.  This is better anyway
for gapless playback of tracks which are joined on the disc.  Anyway,
getting the track length exactly right, to the byte, is required in
order for the AccurateRip CRC to match, but the sound of the track will
not be degraded if the beginning or end is not exactly in the right
place.  Usually the first 0.2 seconds (~10K samples, ~40K bytes) and
the end of a track is silence, anyway.

I've actually EXTENSIVELY altered the Rhino "Have a Nice Day" CDs as
I've ripped them, actually truncating garbage from the end of the
tracks.  In all cases, the song fades out to dither (-90 dBFS hiss) but
many tracks have a little bit of the much higher noise floor that
precedes the next track tacked onto the end of the previous track; I
chop it off in the dither so I don't get this minute noise blip after
the song has faded.  Certainly the "cleaned up" versions would not
match the AccurateRip CRC!

After getting the EAC options set right on my system, AccurateRip
reported much higher success.  Still not perfect, but I feel that the
"different pressing" message may refer to the 1630 at the pressing
plant did not play back exactly the same bits when a subsequent glass
master was cut.  So CDs from different glass masters may in fact not be
exactly the same even though they came from the same 1630 format digital
master tape.  I don't think they use 1630s much anymore.  One engineer
who used to work at Atlantic records has said "1630 and reliable are
not words I would use in the same sentence".

Bottom line, if EAC reports "no errors" in secure mode, in just about
all cases it does mean that there were no errors which would affect the
audio quality, but if AccurateRip then complains the file is most likely
different in some insignificant way.  I believe EAC; to me AccurateRip
is just "icing on the cake" because it shows the file is identical even
in insignificant ways.


-- 
Timothy Stockman
------------------------------------------------------------------------
Timothy Stockman's Profile: http://forums.slimdevices.com/member.php?userid=8867
View this thread: http://forums.slimdevices.com/showthread.php?t=43394

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