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Genlock
Genlock (generator locking) is a common technique where the video output of one source (or a specific reference signal from a signal generator) is used to synchronize other picture sources together. The aim in video applications is to ensure the coincidence of signals in time at a combining or switching point. When video instruments are synchronized in this way, they are said to be ''generator-locked'', or ''genlocked''. Possible problems Video signals generated and output by generator-locked instruments are said to be syntonized. Syntonized video signals will be precisely frequency-locked, but because of delays caused by the unequal transmission path lengths, the synchronized signals will exhibit differing phases at various points in the television system. Modern video equipment such as production switchers that have multiple video inputs often include a variable delay on each input to compensate for the phase differences and time all the input signals to precise phase coinci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time Base Corrector
Time base correction (TBC) is a technique to reduce or eliminate errors caused by mechanical instability present in analog recordings on mechanical media. Without time base correction, a signal from a videotape recorder (VTR) or videocassette recorder (VCR) cannot be mixed with other, more time-stable devices found in television studios and post-production facilities. Most broadcast quality VCRs have simple time base correctors built in though external TBCs are often used. Some high-end domestic analog video recorders and camcorders also include a TBC circuit, which typically can be switched off if required. Time base correction counteracts errors by buffering the video signal as it comes off the videotape at an unsteady rate, and releasing it at a steady rate. TBCs also allow a variable delay in the video stream. By adjusting the rate and delay using a waveform monitor and a vectorscope, the corrected signal can now match the timing of the other devices in the system. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frame Synchronizer (video)
Time base correction (TBC) is a technique to reduce or eliminate errors caused by mechanical instability present in analog recordings on mechanical media. Without time base correction, a signal from a videotape recorder (VTR) or videocassette recorder (VCR) cannot be mixed with other, more time-stable devices found in television studios and post-production facilities. Most broadcast quality VCRs have simple time base correctors built in though external TBCs are often used. Some high-end domestic analog video recorders and camcorders also include a TBC circuit, which typically can be switched off if required. Time base correction counteracts errors by buffering the video signal as it comes off the videotape at an unsteady rate, and releasing it at a steady rate. TBCs also allow a variable delay in the video stream. By adjusting the rate and delay using a waveform monitor and a vectorscope, the corrected signal can now match the timing of the other devices in the system. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Television Camera
A professional video camera (often called a television camera even though its use has spread beyond television) is a high-end device for creating electronic moving images (as opposed to a movie camera, that earlier recorded the images on film). Originally developed for use in television studios or with outside broadcast trucks, they are now also used for music videos, direct-to-video movies (see digital movie camera), corporate and educational videos, wedding videos, among other uses. Since the 2000s, most professional video cameras are digital (instead of analog) professional video cameras. The distinction between professional video cameras and movie cameras became much smaller as HD digital video cameras with sensors the same size as 35mm movie cameras - plus dynamic range (exposure latitude) and color rendition approaching film quality - were introduced in the late 2010s. Nowadays, HDTV cameras designed for broadcast television, news, sports, events and other works such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Professional Video Camera
A professional video camera (often called a television camera even though its use has spread beyond television) is a high-end device for creating electronic moving images (as opposed to a movie camera, that earlier recorded the images on film). Originally developed for use in television studios or with outside broadcast trucks, they are now also used for music videos, direct-to-video movies (see digital movie camera), corporate and educational videos, wedding videos, among other uses. Since the 2000s, most professional video cameras are digital (instead of analog) professional video cameras. The distinction between professional video cameras and movie cameras became much smaller as HD digital video cameras with sensors the same size as 35mm movie cameras - plus dynamic range (exposure latitude) and color rendition approaching film quality - were introduced in the late 2010s. Nowadays, HDTV cameras designed for broadcast television, news, sports, events and other works such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tri-level Sync
Tri-level sync is an analogue video synchronization pulse primarily used for the locking of high-definition video signals (genlock). It is preferred in HD environments over black and burst, as timing jitter is reduced due to the nature of its higher frequency. It also benefits from having no DC content, as the pulses are in both polarities. Synchronization Modern real-time multi-source HD facilities have many pieces of equipment that all output HD- SDI video. If this baseband video is to be mixed, switched or luma keyed with any other sources, then they will need to be synchronous, i.e. the first pixel of the first line must be transmitted at the same time (within a few microseconds). This then allows the switcher A switcher, shunter, yard pilot, switch engine, yard goat, or shifter is a small railroad locomotive used for manoeuvring railroad cars inside a rail yard in a process known as ''switching'' (US) or ''shunting'' (UK). Switchers are not inten ... to cut, mix ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vision Mixer
A vision mixer is a device used to select between several different live video sources and, in some cases, compositing live video sources together to create visual effects. In most of the world, both the equipment and its operator are called a vision mixer or video mixer; however, in the United States, the equipment is called a video switcher, production switcher or video production switcher, and its operator is known as a technical director (TD). The role of the vision mixer for video is similar to what a mixing console does for audio. Typically a vision mixer would be found in a video production environment such as a production control room of a television studio, production truck or post-production facility. Capabilities and usage Besides hard cuts (switching directly between two input signals), mixers can also generate a variety of transitions, from simple dissolves to pattern wipes. Additionally, most vision mixers can perform keying operations (called mattes in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colorburst
Colorburst is an analog video, composite video signal generated by a video-signal generator used to keep the chrominance subcarrier synchronized in a color television signal. By synchronizing an oscillator with the colorburst at the back porch (beginning) of each scan line, a television receiver is able to restore the suppressed carrier of the chrominance (color) signals, and in turn decode the color information. The most common use of colorburst is to genlock equipment together as a common reference with a vision mixer in a television studio using a multi-camera setup. Explanation In NTSC, its frequency is exactly 315/88 = 3.579 MHz with a phase of 180°. PAL uses a frequency of exactly 4.43361875 MHz, with its phase alternating between 135° and 225° from line to line. Since the colorburst signal has a known amplitude, it is sometimes used as a reference level when compensating for amplitude variations in the overall signal. SECAM is unique in n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal Generator
A signal generator is one of a class of electronic devices that generates electrical signals with set properties of amplitude, frequency, and wave shape. These generated signals are used as a stimulus for electronic measurements, typically used in designing, testing, troubleshooting, and repairing electronic or electroacoustic devices, though it often has artistic uses as well. There are many different types of signal generators with different purposes and applications and at varying levels of expense. These types include function generators, RF and microwave signal generators, pitch generators, arbitrary waveform generators, digital pattern generators, and frequency generators. In general, no device is suitable for all possible applications. A signal generator may be as simple as an oscillator with calibrated frequency and amplitude. More general-purpose signal generators allow control of all the characteristics of a signal. Modern general-purpose signal generators will have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Film And Video Technology
A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmosphere through the use of moving images. These images are generally accompanied by sound and, more rarely, other sensory stimulations. The word "cinema", short for cinematography, is often used to refer to filmmaking and the film industry, and to the art form that is the result of it. Recording and transmission of film The moving images of a film are created by photographing actual scenes with a motion-picture camera, by photographing drawings or miniature models using traditional animation techniques, by means of CGI and computer animation, or by a combination of some or all of these techniques, and other visual effects. Before the introduction of digital production, series of still images were recorded on a strip of chemically sensitize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synchronization
Synchronization is the coordination of events to operate a system in unison. For example, the conductor of an orchestra keeps the orchestra synchronized or ''in time''. Systems that operate with all parts in synchrony are said to be synchronous or ''in sync''—and those that are not are '' asynchronous''. Today, time synchronization can occur between systems around the world through satellite navigation signals and other time and frequency transfer techniques. Navigation and railways Time-keeping and synchronization of clocks is a critical problem in long-distance ocean navigation. Before radio navigation and satellite-based navigation, navigators required accurate time in conjunction with astronomical observations to determine how far east or west their vessel traveled. The invention of an accurate marine chronometer revolutionized marine navigation. By the end of the 19th century, important ports provided time signals in the form of a signal gun, flag, or dropping ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical Blanking Interval
In a raster scan display, the vertical blanking interval (VBI), also known as the vertical interval or VBLANK, is the time between the end of the final visible line of a frame or field and the beginning of the first visible line of the next frame. It is present in analog television, VGA, DVI and other signals. In raster cathode ray tube displays, the blank level is usually supplied during this period to avoid painting the retrace line — see raster scan for details; signal sources such as television broadcasts do not supply image information during the blanking period. Digital displays usually will not display incoming data stream during the blanking interval even if present. The VBI was originally needed because of the inductive inertia of the magnetic coils which deflect the electron beam vertically in a CRT; the magnetic field, and hence the position being drawn, cannot change instantly. Additionally, the speed of older circuits was limited. For horizontal deflection, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic News Gathering
Electronic news-gathering (ENG) or electronic journalism (EJ) is usage of electronic video and audio technologies by reporters to gather and present news instead of using film cameras. The term was coined during the rise of videotape technology in the 1970s. ENG can involve anything from a single reporter with a single professional video camera, to an entire television crew taking a truck on location. Beginnings Shortcomings of film The term ENG was created as television news departments moved from film-based news-gathering to electronic field production technology in the 1970s. Since film requires chemical processing before it can be viewed and edited, it generally took at least an hour from the time the film arrived back at the television station or network news department until it was ready to be broadcast. Film editing was done by hand on what was known as " color reversal" film, usually Kodak Ektachrome, meaning there were no negatives. Color reversal film had re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
