A read-only DVD disc used for movies endorsed by the DVD Forum. Offering visual quality superior to VHS tapes, the first DVD-Video players became available at the end of 1996. A single-sided, single-layer DVD-Video disc holds approximately 133 minutes of full-motion video using MPEG-2 compression. The 133 minutes is an approximate number, because compression is not a fixed rate. It is based upon the amount of motion taking place in each scene. DVD-Video discs can be played in regular DVD players, high-definition Blu-ray players and computer DVD-ROM drives. Two Layers; Two Sides DVD-Video discs can be recorded on both sides, and two layers per side can be used. Thus, up to four two-hour movies can be contained on a single volume. DVD-Video supports Dolby Digital surround sound, which provides five discrete channels of CD-quality audio plus a subwoofer (5.1 channel). See DVD, DVD storage capacities, DVD drives, VOB, DVD-ROM and DTV.