Sound could be stored in either analog or digital format and in a variety of surround sound formats; NTSC discs could carry two analog audio tracks, plus two uncompressed PCM digital audio tracks, which were (EFM, CIRC, 16-bit and 44.056 kHz sample rate). PAL discs could carry one pair of audio tracks, either analog or digital and the digital tracks on a PAL disc were 16-bit 44.1 kHz as on a CD; in the UK, the term "LaserVision" is used to refer to discs with analog sound, while "LaserDisc" is used for those with digital audio. The digital sound signal in both formats are EFM-encoded as in CD. Dolby Digital (also called AC-3) and DTS—which are now common on DVD titles—first became available on LaserDisc, and Star Wars: Episode I – The Phantom Menace (1999) which was released on LaserDisc in Japan, is among the first home video releases ever to include 6.1 channel Dolby Digital EX Surround. Unlike DVDs, which carry Dolby Digital audio in digital form, LaserDiscs store Dolby Digital in a frequency modulated form within a track normally used for analog audio. Extracting Dolby Digital from a LaserDisc required a player equipped with a special "AC-3 RF" output and an external demodulator in addition to an AC-3 decoder. The demodulator was necessary to convert the 2.88 MHz modulated AC-3 information on the disc into a 384 kbit/s signal that the decoder could handle. DTS audio, when available on a disc, replaced the digital audio tracks; hearing DTS sound required only an S/PDIF compliant digital connection to a DTS decoder.
DVDలు ఏ సౌండ్ ఫార్మాటింగ్ను ఉపయోగిస్తాయి?
Dolby Digital audio in digital form