VCR and VHS Video Technology

A videocassette recorder (VCR) is a device that records and plays back television pictures and sound on magnetic tape held in a cassette. From the late 1970s through the 1990s, VCRs were the standard way to record broadcasts for later viewing and to watch pre-recorded movies at home. The most widespread consumer format was VHS, the Video Home System, which used half-inch-wide tape in a familiar rectangular cassette.

Television pictures contain far more information than audio, so recording them on tape required a special technique called helical scanning. Instead of fixed heads, the VCR wraps the tape part way around a tilted spinning drum carrying small recording heads. As the drum rotates and the tape moves slowly past it, the heads trace long diagonal stripes across the tape, each holding part of the picture. This greatly increases the effective writing speed and lets a slow-moving tape store the wide bandwidth of a video signal.

VHS competed with other formats during its era, and tapes were available in different recording-length grades. Picture quality was limited by the analogue recording and by the colour-under method used to store the colour information, and copies made from copies degraded noticeably. VHS was eventually displaced by optical discs such as the DVD and later by digital recording and streaming, which offer higher quality, random access and no physical wear of the recording medium.

Frequently asked questions

How does a VCR record video on tape?

It uses helical scanning, wrapping the tape around a tilted spinning drum with heads that write diagonal stripes. This raises the writing speed enough to record the wide video bandwidth.

What is VHS?

VHS, the Video Home System, was the dominant consumer videocassette format, using half-inch tape in a cassette for recording broadcasts and playing pre-recorded movies.

Why was VHS replaced?

Optical discs and digital recording offered higher picture quality, instant access to any point, and no tape wear, so they superseded VHS and the VCR.