Wikipedia:
> Although similar in appearance to compact discs or DVDs, early LaserDiscs used analog video stored in the composite domain (having a video bandwidth and resolution approximately equivalent to the 1-inch (25 mm) Type C videotape format) with analog FM stereo sound and PCM digital audio. Later discs used D-2 instead of Type C videotape for mastering. The LaserDisc at its most fundamental level was still recorded as a series of pits and lands much like CDs, DVDs, and even Blu-ray Discs are today. In true digital media the pits, or their edges, directly represent 1s and 0s of a binary digital information stream. On a LaserDisc, the information is encoded as analog frequency modulation and is contained in the lengths and spacing of the pits.