Commercially available since the late 1930s, the television is common in homes, businesses and institutions, particularly as a source of entertainment and news. Since the 1970s the availability of video cassettes, laserdiscs, DVDs and now Blu-ray Discs, have resulted in the television set frequently being used for viewing recorded as well as broadcast material.
Older televisions were manufactured in a 4 by 3 aspect ratio — known as Standard Definition. But theatrically released movies are usually in a wider aspect, taking advantage of the human field of vision (which is wider across horizontally, like a rectangle). HDTV signals are sent in a 16 by 9 aspect ratio, mimicking the wide scope of movies. HDTV’s aspect ratio makes for a more immersive and intense viewing experience.
HDTV results in crystal clear, noise-free pictures and CD quality sound. It provides either 720 or 1080 (depending on your set) lines of resolution compared to the 525 lines viewers are accustomed to in the United States.
The term video (“video” meaning “I see”, from the Latin verb “videre”) commonly refers to several storage formats for moving pictures: digital video formats, including Blu-ray Disc, DVD, QuickTime, and MPEG-4; and analog videotapes, including VHS and Betamax. Video can be recorded and transmitted in various physical media: in magnetic tape when recorded as PAL or NTSC electric signals by video cameras, or in MPEG-4 or DV digital media, such as hard drives or SD cards, when recorded by digital cameras.
Quality of video essentially depends on the capturing method and storage used. Digital television (DTV) is a relatively recent format with higher quality than earlier television formats and has become a standard for television video.
3D-video, digital video in three dimensions, premiered at the end of 20th century. Six or eight cameras with realtime depth measurement are typically used to capture 3D-video streams. The format of 3D-video is fixed in MPEG-4 Part 16 Animation Framework eXtension (AFX).
Cable television programming is often divided between basic and premium programming. Basic cable TV networks are generally transmitted without any scrambling or other encryption methods. Basic cable networks receive at least some funding through “per-subscriber fees,” fees paid by the cable TV systems for the right to include the network in its channel lineup. Most basic cable TV networks also include advertising to supplement the fees, since their programming costs typically are not covered by per-subscriber fees alone.
Most cable systems divide their channel lineups (“tiers”) into three or four basic channel packages. A must-carry rule requires all cable TV systems to carry all full-power local broadcast stations in the designated market on their lineups, unless those stations opt to invoke retransmission consent and demand compensation, in which case the cable provider can decline to carry the channel. Cable TV systems are also required to offer a subscription package that provides these broadcast channels at a lower rate than the standard subscription rate. The basic programming package offered by cable TV systems is usually known as “basic cable” and provides access to a large number of cable TV channels, as well as broadcast television networks (e.g., ABC, CBS, CW, Fox, NBC, PBS), local-access television channels, and several channels devoted to infomercials and home shopping to defray costs. Most systems differentiate between basic cable, which has locals, home shopping channels and local access channels, and expanded basic, which has everything in basic cable, but has a lot more nationals. Basic cable usually has 20 channels (including locals), while expanded basic has 70 (including locals). A modern TV with a “Digital Cable Ready” TV can received extra HD local stations, such NBC WeatherPlus and ABC
Most cable systems offer pay per view channels where users can watch individual movies, live programs, sports, etc. for an additional fee for single viewing at a scheduled time. Some cable systems have begun to offer on-demand programming, where customers can select programs from a list of offerings including recent releases of movies, concerts, sports, and reruns of TV shows and specials and start the program whenever they wish, as if they were watching a DVD or a VHS tape.
Subscribers wanting access to digital cable channels must have a special cable box (or, more recently, a “Digital Cable Ready” TV and a CableCARD) to receive them.
Premium cable refers to networks, such as HBO, Cinemax, Showtime, Starz, and the Disney Channel (prior to 1997) that scramble or encrypt their signals so that only those paying additional monthly fees to their cable TV system can legally view them (via the use of cable box or converter). Because their programming is commercial-free (except for promos in-between shows for the networks’ own content), these networks command much higher fees from cable TV systems.
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