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B-MAC
B-MAC is a form of analog video encoding, specifically a type of Multiplexed Analogue Components (MAC) encoding. MAC encoding was designed in the mid 80s for use with Direct Broadcast Satellite systems. Other analog video encoding systems include NTSC, PAL and SECAM. Unlike the Frequency-division multiplexing, Frequency-Division Multiplexing (FDM) method used in those, MAC encoding uses a Time-division multiplexing, Time-Division Multiplexing (TDM) method. B-MAC was a proprietary MAC encoding used by Scientific Atlanta, Scientific-Atlanta for encrypting broadcast video services; the full name was "Multiple Analogue Component, Type B". Usage Both 625 lines, 625 and 525 lines, 525 line versions of B-MAC were developed and used. This system was used in South Africa by Multichoice, and Australia by Optus (for Television receive-only, TVRO until 2000). B-MAC was used for satellite broadcasts of the American Forces Network, American Forces Radio and Television Service from the earl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiplexed Analogue Components
Multiplexed Analogue Components (MAC) was an analog television standard where luminance and chrominance components were transmitted separately. This was an evolution from older color TV systems (such as PAL or SECAM) where there was interference between chrominance and luminance. MAC was originally proposed in the 1980s for use on a Europe-wide terrestrial HDTV system. Terrestrial transmission tests were conducted in France, although the system was never used for that purpose. Various variants were developed, collectively known as the "MAC/packet" family. In 1985 MAC was recommended for satellite and cable broadcasts by the European Broadcasting Union (EBU), with specific variants for each medium. C-MAC/packet was intended for Direct Broadcast Satellite (DBS), D-MAC/packet for wide-band cable, and D2-MAC/packet for both for DBS and narrow-band cable. History MAC was originally developed by the Independent Broadcasting Authority in the early 1980, as a system for deli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiplexed Analogue Components Transmission (simulation)
In telecommunications and computer networking, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource—a physical transmission medium. For example, in telecommunications, several telephone calls may be carried using one wire. Multiplexing originated in telegraphy in the 1870s, and is now widely applied in communications. In telephony, George Owen Squier is credited with the development of telephone carrier multiplexing in 1910. The multiplexed signal is transmitted over a communication channel such as a cable. The multiplexing divides the capacity of the communication channel into several logical channels, one for each message signal or data stream to be transferred. A reverse process, known as demultiplexing, extracts the original channels on the receiver end. A device that performs the multiplexing is called a multiplexer (MUX), and a d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frame Rate
Frame rate, most commonly expressed in frame/s, or FPS, is typically the frequency (rate) at which consecutive images (Film frame, frames) are captured or displayed. This definition applies to film and video cameras, computer animation, and motion capture systems. In these contexts, frame rate may be used interchangeably with and refresh rate, which are expressed in hertz. Additionally, in the context of computer graphics performance, FPS is the rate at which a system, particularly a GPU, is able to generate frames, and refresh rate is the frequency at which a display shows completed frames. In electronic camera specifications frame rate refers to the maximum possible rate frames could be captured, but in practice, other settings (such as exposure time) may reduce the actual frequency to a lower number than the frame rate. Human vision The temporal sensitivity and resolution of human vision varies depending on the type and characteristics of visual stimulus, and it differs betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrominance
Chrominance (''chroma'' or ''C'' for short) is the signal used in video systems to convey the color information of the picture (see YUV color model), separately from the accompanying Luma (video), luma signal (or Y' for short). Chrominance is usually represented as two color-difference components: U = B-Y, B′ − Y′ (blue − luma) and V = R-Y, R′ − Y′ (red − luma). Each of these different components may have scale factors and offsets applied to it, as specified by the applicable video standard. In composite video signals, the U and V signals modulate a color subcarrier signal, and the result is referred to as the chrominance signal; the Phase (waves), phase and amplitude of this modulated chrominance signal correspond approximately to the hue and Saturation (color theory), saturation of the color. In digital-video and still-image color spaces such as Y′CbCr, the luma and chrominance components are digita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luma (video)
In video, luma (Y') represents the brightness in an image (the "black-and-white" or achromatic portion of the image). Luma is typically paired with chrominance. Luma represents the grey, achromatic image, while the chroma components represent the color information. Converting RGB color model, R′G′B′ sources (such as the output of a three-CCD camera) into luma and chroma allows for chroma subsampling: because human vision has finer spatial sensitivity to luminance ("black and white") differences than chromatic differences, video systems can store and transmit chromatic information at lower resolution, optimizing perceived detail at a particular bandwidth. Luma versus relative luminance Luma is the weighted sum of gamma-compressed R′G′B′ components of a color video—the ''prime symbols'' ′ denote Gamma correction, gamma compression. The word was proposed to prevent confusion between luma as implemented in video engineering and relative luminance as used in color s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
YPbPr
YPbPr or Y'P'bP'r, also written as , is a color space used in video electronics, in particular in reference to component video cables. Like YCBCR, it is based on gamma corrected RGB primaries; the two are numerically equivalent but YPBPR is designed for use in analog systems while YCBCR is intended for digital video. The EOTF (gamma correction) may be different from common sRGB EOTF and BT.1886 EOTF. Sync is carried on the Y channel and is a bi-level sync signal, but in HD formats a tri-level sync is used and is typically carried on all channels. YPBPR is commonly referred to as ''component video'' by manufacturers; however, there are many types of component video, most of which are some form of RGB. Some video cards come with video-in video-out (VIVO) ports for connecting to component video devices. Technical details Y'P'bP'r can be derived from a gamma corrected R'G'B' signal with a typical range of 0-700 mV. The first step is converting to Y', R'-Y' and B'-Y'. Y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Scrambling Algorithm
The Common Scrambling Algorithm (CSA) is the encryption algorithm used in the DVB digital television broadcasting for encrypting video streams. CSA was specified by ETSI and adopted by the DVB consortium in May 1994. It is being succeeded by CSA3, based on a combination of 128-bit AES and a confidential block cipher, XRC. However, CSA3 is not yet in any significant use, so CSA continues to be the dominant cipher for protecting DVB broadcasts. History CSA was largely kept secret until 2002. The patent papers gave some hints, but important details, like the layout of the so-called S-boxes, remained secret. Without these, free implementations of the algorithm was not possible. Initially, CSA was to remain implemented in hardware only, making it difficult to reverse engineer existing implementations. In 2002 FreeDec was released, implementing CSA in software. Though released as binary only, disassembly revealed the missing details and allowed reimplementation of the algorithm in hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EuroCrypt
EuroCrypt is a conditional access system for Multiplexed Analogue Components-encoded analogue satellite television Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location.ITU Radio Regulations, Section IV. Radio Stations and Systems .... It had several versions (M, S and S2). It supported receivers with card slots and those with embedded keys. Its most widespread use was in Scandinavia, where the only EuroCrypt protected broadcasts remained until July 2006 (in France, they stopped in 1998). It was also hacked with pirate cards, which was popular in many countries in Europe, especially in order to watch English-language channels such as Filmnet Plus and TV1000. EuroCrypt evolved into the Viaccess system for digital television. SourcesFrequency List dated 1998.Denmark's Radio receiver info Digital television Digital rights management systems ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NICAM
Near Instantaneous Companded Audio Multiplex (NICAM) is an early form of lossy compression for digital audio. It was originally developed in the early 1970s for point-to-point links within broadcasting networks.Croll, M.G., Osborne, D.W. and Spicer, C.R. (1974), ''Digital sound signals: the present BBC distribution system and a proposal for bit-rate reduction by digital companding''. IEE Conference publication No. 119, pp. 90–96 In the 1980s, broadcasters began to use NICAM compression for transmissions of stereo TV sound to the public. History Near-instantaneous companding The idea was first described in 1964. In this, the 'ranging' was to be applied to the analogue signal before the analogue-to-digital converter (ADC) and after the digital-to-analogue converter (DAC). The application of this to broadcasting, in which the companding was to be done entirely digitally after the ADC and before the DAC, was described in a 1972 BBC Research Report. Point-to-point links NI ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-return-to-zero
In telecommunications, a non-return-to-zero (NRZ) line code is a binary code in which ones are represented by one significant condition, usually a positive voltage, while zeros are represented by some other significant condition, usually a negative voltage, with no other neutral or rest condition. For a given data signaling rate, i.e., bit rate, the NRZ code requires only half the baseband bandwidth required by the Manchester code (the passband bandwidth is the same). The pulses in NRZ have more energy than a return-to-zero (RZ) code, which also has an additional rest state beside the conditions for ones and zeros. When used to represent data in an asynchronous communication scheme, the absence of a neutral state requires other mechanisms for bit synchronization when a separate clock signal is not available. Since NRZ is not inherently a self-clocking signal, some additional synchronization technique must be used for avoiding bit slips; examples of such techniques are a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teletext
Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipped television sets. Teletext sends data in the broadcast signal, hidden in the invisible vertical blanking interval area at the top and bottom of the screen. The teletext decoder in the television buffers this information as a series of "pages", each given a number. The user can display chosen pages using their remote control. In broad terms, it can be considered as Videotex, a system for the delivery of information to a user in a computer-like format, typically displayed on a television or a dumb terminal, but that designation is usually reserved for systems that provide bi-directional communication, such as Prestel or Minitel. Teletext was created in the United Kingdom in the early 1970s by John Adams, Philips' lead designer for video display units to provide closed captioning to television shows for the hearing impaired. Public teletext information services were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Composite Video
Composite video, also known as CVBS (composite video baseband signal or color, video, blanking and sync), is an analog video format that combines image information—such as brightness (luminance), color (chrominance), and synchronization, into a single signal transmitted over one channel. It is most commonly used for standard-definition television, and is sometimes referred to as ''SD video''. The signal is typically carried on a yellow RCA connector, with separate connectors used for left and right audio channels. In professional equipment, a BNC connector is often used instead. Other connector types may appear in compact consumer devices like digital cameras. Composite video supports several line resolutions, including 405-line, 525-line, and 625-line interlaced formats. It exists in three major regional variants based on analog color encoding standards: NTSC, PAL, and SECAM. The same format can also be used to transmit monochrome (black-and-white) video. Signal comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
