Method to make LG GSA-H55N read some lead out sectors

As the drive has an audio read offset of +102 samples (offset correction in PerfectRip therefore -102 samples) it is important to read the sector after the last possible LBA according to the TOC on audio or mixed mode CDs.

The drive reports “logical block address out of range” when attempting to do a single sector read on that LBA. So sectors supposed belonging to the lead out cannot be accessed that way.

While being “smart” enough to deny access to those sectors directly it is “dumb” enough to allow it if you send a READ CD command with the last valid LBA (for the last sector before lead out) along with a transfer length of whatever value higher than 1. The amount of lead out sectors which can be read seems to be limited by the 64k buffer size restriction only. So I could get 25 sectors of lead out that way with subchannel data.

Having figured this out, I gave Exact Audio Copy 0.99pb3 and PerfectRip 1.00 b28d a try. EAC could read the complete last track including the 102 “lead out samples” in every mode by checking the “overread into lead-in and lead-out” box in the drive settings. PerfectRip could not, regardless of the “length per read command” setting.

So this information maybe can be used in future PerfectRip versions to enable lead out reading support for more drives.

Key information:

  • self-burned CD-R with lead out start at LBA 1950
  • used drive is an LG GSA-H55N, product revision level 1.05
  • lead out accessible by performing a READ CD command with LBA 1949 and tranfer length of 26
  • used CDB is BE 00 00 00 07 9D 00 00 1A F8 01 00
  • method was not working with the Plextor PX-740A rebranded BenQ drive

EDIT: product revision level for the LG drive added

Wow, cool, thanks for sharing, perhaps it’ll be implemented sometime soon in PerfectRip.

I remember a member called bifmud also mentioned a method (post 21):

Hi, thanks for your contribution, there’s something I would like to precise…

If you want your rips to abide by the absolute zero reference
you have to take AccurateRip value for your drive, substract 30
and change the sign. So -(+102-30)=-72 to be entered in main
channel read offset correction field under drive calibrate window.

Oh, yes, I have read about it before but I just forgot. Thanks for reminding me of it.