General questions about EFM

While consulting this massive forum, I have encountered several times the concept of EFM, but I haven’t made out yet what does it mean and why is so important.

It will be great if someone could answer some questions about EFM.

  1. What does EFM stand for?
  2. What does the Alcohol 120% writing option “Bypass EFM errors” do?
  3. What does the assertion “{Certain Burner Name} is EFM capable” mean?
  4. Which protections require an EFM capable writer.
  5. When copying a protected cd/dvd which requires a EFM capable writer, do I have to always activate the corresponding Alcohol 120º option, or only if my burner is not EFM capable?

And finally, is my Lite-On SOHW-1653S an EFM capable writer?

Thank you very much.

Q4 = Safedisc 2, 3 and 4.

  1. EFM = Eight to Fourteen modulation
  2. Attempt to work around defective EFM Encoding (with limited effectiveness)
  3. Few, if any, are fully capable, this harks back to the “Sheep test”
  4. Answered, though the levels in SD2 were tracked in the “sheep test”, as later versions are tougher.
  5. YES, if the writer does not meet the level required

The EFM issue revolves around the “weak sectors”, where certain regular bit patterns cause an error in the EFM encoding. Some drives are able to handle some of the patterns but not others. Many drives are able to correct their own error on re-reading, but using the writer to read means you are caought out be ATIP checking, and using an ATIP hider to prevent that can result in the ATIP hider being noticed by later protections.

The 1653S drive, according to this review - http://www.cdrinfo.com/Sections/Reviews/Specific.aspx?ArticleId=12496&PageId=4 - is beaten by SD2.9 or above - pretty good “sheep” for a DVD, but “Bypass EFM error” is unable to help it - in most tests, actually, it seems rare for “Bypass EFM error” to achieve anything, at least on their sample set of readers.

CloneCD emulation may be more effective, but then you enter another stage of the protection war, where the anti-protection tool can be detected.

Thanks Matth for your brief explanation of EFM.
But I do not agree with the 1653S not being able to backup SD2.9 or above, I’ve made a working backup of Vampire Bloodlines (SD 3.20.xx) without emulation of any kind. The problem of the review you mention might be that they burned the images at max speed (I don’t need to hurry so much :)).

Thank you both.