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Does anyone know why are there different results in accuraterip database? For example:

When finish with ripping an audio CD, the results might look like:

Track 1 (98/120) Accurately ripped
Track 2 (98/120) Accurately ripped
Track 3 (98/120) Accurately ripped
Track 4 (98/120) Accurately ripped
Track 5 (98/120) Accurately ripped
Track 6 (98/120) Accurately ripped

Offsetted by -6
Track 1 (22/120) Accurately ripped
Track 2 (22/120) Accurately ripped
Track 3 (22/120) Accurately ripped
Track 4 (22/120) Accurately ripped
Track 5 (22/120) Accurately ripped
Track 6 (22/120) Accurately ripped

What is the offset? are they both correct?

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1 Answer 1

up vote 1 down vote accepted

I'm quoting this from here:

Drive read offsets

Very few CD drives actually start reading data from audio CDs exactly at the sector requested by DAE software. There are drives that are off by over 1 sector (1/75th of a second), but most are off by much less (1/250 to 1/350 second). Most modern CD drives have "Accurate Stream" technology, so there's no "jitter", meaning in this case that the variance is consistent from read to read, and will tend to be the same for all drives of a certain make & model.

The AccurateRip database allows one to find out the read offset, which is normally constant for given make & model of CD drive. This number can then be used by DAE software to ensure that each track is ripped from its exact start to its exact finish.

The offset is given in samples. One "sample" on an audio CD is 4 bytes, consisting of a 2-byte left-channel value and a 2-byte right-channel value. There are 2352 bytes, or 588 samples, in each sector of an audio CD, corresponding to 1/75th of a second of sound. Therefore, an AccurateRip offset of +134 means the drive consistently delivers data from 536 bytes behind (earlier than) where it was asked to read from, so the DAE software needs to look that far ahead (hence the positive offset) in order to get the right data.

When offsets are taken into account, the DAE software might have to ask the drive to "overread" into the lead-in or lead-out portions of the disc, where there's no audio data. Some drives can't be asked to do it, some drives will try to do it and fail, and some will just return null samples (a stream of "0" bytes, a.k.a. digital silence).

If the drive can't overread, then there will be samples missing from the extracted track. The DAE software can correct for this by padding the track with digital silence so it's the correct length.

Soooooooooooooooooooooooooooooooooo...

Basically both rips are accurate, since the DAE software should correct the situation

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