What does EFM stand for and how do you know if your cdrw can burn in EFM mode?

EFM will allow your cd-writer write pattern weak sectors of certain protections (moreover other things are associated to this). In order to recognize if your cd-writer is good is using a tool called “sheep” that says you how well write the device those sectors.

You can find it at DVD/CD protection section.

Eight-to-Fourteen Modulation, or EFM as it is abbreviated, is an encoding technique used by CDs and provides a way of countering errors by encoding a byte into 2 bytes. Using EFM the data is broken into 8-bit blocks (bytes). Each 8-bit block is translated into a corresponding 14-bit codeword using a predefined lookup table. The 14-bit codeword are chosen so that binary ones are always separated by a minimum of two and a maximum of ten binary zeroes. EFM maximizes the number of transitions possible with an arbitrary pit and land length which is determined by the wavelength of the laser light used to read the data. Eight-to-Fourteen Modulation uses an RLL encoding scheme.

Just revisiting the club (it’s been awhile) - and saying hello with some more EFM info; which Nemesys already defined precisely - but a slightly more comprehensive answer can be found here.

As well; there’s an excellent ExactAudioCopy (EAC/Lame) review and how CD Drives work in general.

Contrary to popular belief, a pit does not represent a digital 1. CDs work on such a small scale that a string of ever-changing 0-to-1 and 1-to-0 transitions would be nearly impossible to read correctly. What happens when a word ends with a 1 and the next starts with a 1? Where does one sample end and the next begin? To counter this problem, the engineers at Philips and Sony introduced a modulation technique called Eight-to-Fourteen. In EFM, every possible 8-bit word – the length agreed upon for the RedBook standard and ranging from 0000 0000 to 1111 1111 – has a 14-bit equivalent. These 14-bit equivalent words are generated such that there are always more than two but less than ten consecutive zeros. The result? Information stored on a CD is never shorter than 3 bits or longer than 11 bits. These pit lengths are called T3 to T11. The transition from pit to flat is now easy to track to represent the amplitude information of a waveform.

Like the groove of an LP, CD stores all of its data in a single string. This string of data consists of the already mentioned EFM words in the form of pits and flats plus the so-called sub code. The sub code carries information about the laser location to enable track selection. The Table of Contents or TOC code directs the laser to the correct spot on the disc (we’ll see later that ‘correct’ can vary). Besides the sub code, CD protocol requires a synchronization prompt, which is inserted into the string at various places. This synchronization word helps to regulate the CD player’s drive motor.