Do all DVD-Video discs have Dolby Digital soundtracks?
Discs in countries such as the U.S. that use the NTSC broadcast TV standard must provide at least one soundtrack in either of two formats: Dolby Digital or PCM (the format used on CDs). In countries using the PAL TV standard, including much of Europe, the discs must include at least one soundtrack in any one of three formats: Dolby Digital, PCM, or MPEG. As a result of these requirements and the options they permit, not all discs have Dolby Digital soundtracks. Dolby Digital, however, is the only universal multichannel standard, and every DVD player sold worldwide incorporates Dolby Digital decoding. Therefore the vast majority of discs do include at least one Dolby Digital soundtrack.
