VHS
The Video Home System, better known by its acronym VHS, is the recording and playing standard for video cassette recorders (VCRs), developed by JVC and launched in 1976.
It became a standard format for consumer recording and viewing in the 1980s after competing in a fierce format war with Sony's Betamax and, to a lesser extent, Philips's Video 2000.
A VHS cassette contains a 12.65 mm (1/2-inch aprox.) wide magnetic tape which is wound from one of two spools to the other, allowing it to slowly pass by the reader head of the video cassette recorder. VHS initially offered a longer playing time than the Betamax system, and it also had the advantage of having a far less complex tape transport mechanism than the Sony offering. A VHS machine can rewind and fast forward the tape considerably faster than a Betamax VCR since it unthreads the tape from the playback heads before commencing any high-speed winding. On the other hand, Betamax offers a superior picture quality to VHS.
Several improved versions of VHS exist, most notably S-VHS, an improved analog standard, and D-VHS, which records digital video onto a VHS form factor tape. Devices have also been invented which directly connect a personal computer to VHS tape recorders for use as a data backup device.
VHS-C tapes (C for compact) are used in some camcorders, and can be played back in standard VHS players with an adapter. Its development hampered the sales of the Betamax system somewhat, because the Betamax cassette geometry prevented a similar development.
VHS tapes have approximately 3 MHz of bandwidth, and a horizontal resolution of about 240 lines per picture height (about 320 lines in total). [1] (http://www.hometheaterhifi.com/volume_6_3/essay-video-resolution-july-99.html) The vertical resolution of VHS (and all analog video systems) is determined by the TV standard—about 480 lines are visible in NTSC and about 576 lines in PAL.
Although VHS officially stands for Video Home System, it initially stood for Vertical Helical Scan, after the relative head/tape scan technique. Some early reports claimed that the initials originally stood for Victor Helical Scan system.
VCRs were taken to court and found to have substantial legitimate uses other than copyright infringing uses in the case of Sony Corp. v. Universal City Studios. However, Senator Orrin Hatch has proposed the Induce Act [2] (http://www.theregister.co.uk/2004/06/26/hatch_induce_act/), which, if made law, would effectively reverse this ruling.
In November 2004 the British retail group Dixons announced that it would begin phasing out VHS machines in favour of recordable DVD (DVD-R and DVD plus R) and personal video recorders, leading many observers to predict the imminent demise of the VHS system.
External links
- The 'Total Rewind' VCR museum, covering the history of VHS and other vintage formats (http://www.totalrewind.org)
- BBC News article: Death of video recorder in sight (http://news.bbc.co.uk/1/hi/business/4031223.stm)
de:Video Home System fr:Video Home System nl:VHS ja:VHS no:Video home system pl:VHS sv:VHS