VHS vs. DVD - Technical Definitions

VHS is an analog videotape format developed by a consortium of Japanese electronics manufacturers in the early 1980's. To make it affordable to the consumer the standards for NTSC standard broadcast quality video were greatly compromised. The luminance bandwidth was cut in half so detail resolution is a mere 220 lines. Broadcast quality recorders at the time could record up to 450 lines of resolution (Over the air broadcast delivery gets only around 330 lines of resolution to the home). To fit the color information on the VHS tape it was cut down to a mere 20% of the original detail so there are approximately only 40 lines of color information per horizontal line. With modern Hi-Fi VCR you can reproduce Stereo and with some models Virtual Surround sound. Is it close to what you get in the theater?

DVD - Digital Versatile Disc, which is mostly used now as Digital Video Disc - looks like CD and data storage technology is similar: image data are recorded as microscopic pits on a reflective surface, only the pits are far smaller and more densely packed than CD's. Information is recorded as an MPEG-2 highly compressed component digital video signal. Compression rates are roughly 40 to 1 but careful quality control during the mastering process can usually preserve a great deal of the original picture quality in the MPEG-2 data. There are over 480 lines of luminance detail and over 220 lines of color information per line. This is much better than VHS or even LD. While the size of CD and DVD is the same, up to 4.5 GBytes can be stored on DVD (vs. 650 Mbytes on CD).