• Egen
  • Dumper
  • Offline
  • From: United States
  • Registered: 2015-01-29
  • Posts: 193

http://redump.org/disc/29257/

"Missing data in Lead-out Zone. Should be dump with +75 sector offset due to desync issue."

As an owner of this CD and somebody who actually knows how to use EAC, I know that there is data further than the typical "global offset" used by everyone to dump every CD on the planet. What's confusing is that the comment says it needs 75 sectors. Unless I've really started to forget stuff, 75 sectors is +1 to the sample offset in EAC, right? If so, that's incorrect, because this disc needs +2 to the usual sample offset. For example, with my Plextor PX-716A which has a +30 offset, I need to rip this CD with a +32 offset in EAC to catch every sample.

  • Registered: 2006-12-24
  • Posts: 3,846

Sectors, not samples. 1 sector = 588 samples.

  • Egen
  • Dumper
  • Offline
  • From: United States
  • Registered: 2015-01-29
  • Posts: 193

Not samples, sample offset. The part in EAC called "read sample offset correction". For every one unit you change that by, 75 sectors are affected, right? Or no?

The comment is epically confusing hmm

  • Registered: 2006-12-24
  • Posts: 3,846

Sample offset correction is measured in samples, 1 sample = 4 bytes = 1/588 sector.
75 sectors in lead-out means 75*2352 additional bytes of data after the last track, way too large to be called an offset, hence not included.

5 Reply by Egen (edited by Egen 2017-11-15 08:35:35)

  • Egen
  • Dumper
  • Offline
  • From: United States
  • Registered: 2015-01-29
  • Posts: 193

Okay, question about another audio disc comment.

http://redump.org/disc/34204/

"Last 48 bytes of Track 25 filled with 00"

This comment, respectfully, makes no sense. The last 48 bytes are not filled with 00. The disc was created with a +18 offset. If you rip the disc with a +30 offset, then sure, you'll have some extra silent samples, but... they're extra. Why would you increase the offset further than the actual data on the disc exists?

+18 is a ridiculously common offset. Off the top of my head, basically every King Records CD ever has an offset of +18. Why do people insist on ripping every CD with the same offset? That's only taking their drive's offset into account, and there are always two offsets to take into account: the offset of your drive, AND the offset of the drive that created the CD. Most of the time we can't know the offset of the mastering drive, but sometimes we can.

I don't understand this personally. You just introduce silent samples by doing it this way, and you miss non-silent samples on other CDs such as La Pucelle by not adjusting the offset further. What's the point of this - for everyone to get the same incorrect results?

  • Registered: 2006-12-24
  • Posts: 3,846

Egen wrote:

Okay, question about another audio disc comment.

http://redump.org/disc/34204/

"Last 48 bytes of Track 25 filled with 00"

This comment, respectfully, makes no sense.

Dunno, ask Jackal, maybe he suspects that it was dumped incorrectly (without overreading into lead-out).

Egen wrote:

The last 48 bytes are not filled with 00. The disc was created with a +18 offset. If you rip the disc with a +30 offset, then sure, you'll have some extra silent samples, but... they're extra. Why would you increase the offset further than the actual data on the disc exists?

The disc offset for audio CDs is always assumed 0 unless there is data in lead-out or in the first pregap.
http://redump.org/disc/14890/ -- a "possible offset" comment can be used like here, though.