Data is written to CD/DVD using an encoding called eight-to-fourteen modulation, where each eight bits of data are encoded by fourteen bits on disk. The encoding was designed to give the encoded signal some useful properties, such as limiting consecutive identical bits (for clock recovery).
One property that I'm struggling to find motivation for is the low power density at low frequencies. Can someone explain why this property is useful?
the spectrum (power density function) of the encoded sequence vanishes at the low-frequency end
EFM combines high information density ... with low power at the low-frequency end of the modulation bit stream spectrum.
(source: abstract of related paper)