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Time Base Correction
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 such as character generators and video cameras found in television studios and post-production facilities. Time base correction counteracts errors by buffering the video signal as it comes off the videotape at an unsteady rate, and releasing it after a delay at a steady rate. A sync generator provides the timing reference for all devices in the system. By adjusting the delay using a waveform monitor, the corrected signal can be made to match the timing of the other devices in the system. If all of the devices in a system are adjusted so their signals meet the video switcher at the same time and at the same rate, the signals can be mixed. Though external TBCs are often use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analog Recording
Analog recording is a category of techniques used for the recording of analog signals. This enables later playback of the recorded analog audio. Analog audio recording began with mechanical systems such as the phonautograph and phonograph. Later, electronic techniques such as wire recording, wire and tape recorder, tape recording were developed. Analog recording methods store analog signals directly in or on the media. The signal may be stored as a physical texture on a phonograph record, or a fluctuation in the field strength of a magnetic recording. Analog transmission methods use analog signals to distribute audio content. These are in contrast to digital audio where an analog signal is Sampling (signal processing), sampled and Quantization (signal processing), quantized to produce a Digital signal (signal processing), digital signal which is represented, stored and transmitted as discrete numbers. See also * Comparison of analog and digital recording * History of sound re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Python (programming Language)
Python is a high-level programming language, high-level, general-purpose programming language. Its design philosophy emphasizes code readability with the use of significant indentation. Python is type system#DYNAMIC, dynamically type-checked and garbage collection (computer science), garbage-collected. It supports multiple programming paradigms, including structured programming, structured (particularly procedural programming, procedural), object-oriented and functional programming. It is often described as a "batteries included" language due to its comprehensive standard library. Guido van Rossum began working on Python in the late 1980s as a successor to the ABC (programming language), ABC programming language, and he first released it in 1991 as Python 0.9.0. Python 2.0 was released in 2000. Python 3.0, released in 2008, was a major revision not completely backward-compatible with earlier versions. Python 2.7.18, released in 2020, was the last release of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Closed Captioning
Closed captioning (CC) is the process of displaying text on a television, video screen, or other visual display to provide additional or interpretive information, where the viewer is given the choice of whether the text is displayed. Closed captions are typically used as a transcription of the audio portion of a program as it occurs (either verbatim or in edited form), sometimes including descriptions of non-speech elements. Other uses have included providing a textual alternative language translation of a presentation's primary audio language that is usually burned-in (or "open") to the video and unselectable. HTML5 defines subtitles as a "transcription or translation of the dialogue when sound is available but not understood" by the viewer (for example, dialogue in a foreign language) and captions as a "transcription or translation of the dialogue, sound effects, relevant musical cues, and other relevant audio information when sound is unavailable or not clearly audible" (fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JSON
JSON (JavaScript Object Notation, pronounced or ) is an open standard file format and electronic data interchange, data interchange format that uses Human-readable medium and data, human-readable text to store and transmit data objects consisting of name–value pairs and array data type, arrays (or other serialization, serializable values). It is a commonly used data format with diverse uses in electronic data interchange, including that of web applications with server (computing), servers. JSON is a Language-independent specification, language-independent data format. It was derived from JavaScript, but many modern programming languages include code to generate and parse JSON-format data. JSON filenames use the extension .json. Douglas Crockford originally specified the JSON format in the early 2000s. Transcript: He and Chip Morningstar sent the first JSON message in April 2001. Naming and pronunciation The 2017 international standard (ECMA-404 and ISO/IEC 21778:2017) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
D-3 (video)
D-3 is an uncompressed composite digital video format invented at NHK and introduced commercially by Panasonic. It was launched in 1991 to compete with Ampex's D-2. Overview D-3 uses half-inch metal particle tape at 83.88 mm/s (compare to D-2's 19 mm and 131.7 mm/s). Like D-2, the composite video signal is sampled at four times the color subcarrier frequency, with eight bits per sample. Four channels of 48 kHz 16–20 bit PCM audio, and other ancillary data, are inserted during the vertical blanking interval. The aggregate net (error corrected) bitrate of the format is 143 Mbit/s, and because the codec is lossless, it has been used in data applications. Camcorders were available which used this format, and are to date the only digital tape camcorders to use a lossless encoding scheme. The D-5 digital component video format, introduced in 1993 by Panasonic, uses the D-3 transport and tape running at roughly double D-3 speed. The D-3 transport in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
U-matic
U-matic, also known as -inch Type E Helical Scan or SMPTE E, is an analog recording videocassette format developed by Sony. First shown as a prototype in October 1969 and introduced commercially in September 1971, it was among the earliest video formats to house videotape inside a cassette, replacing the reel-to-reel systems common at the time. The format uses tape, earning it the nickname "three-quarter-inch" or simply "three-quarter," in contrast to larger open-reel formats like Type C videotape and quadruplex videotape. The name ''U-matic'' refers to the U-shaped tape path as it threads around the video drum. Unlike most cassette formats, U-matic's supply and take-up reels rotate in opposite directions during playback, fast-forward, and rewind—one clockwise, the other counterclockwise. Each cassette has an internal locking mechanism that secures the tape hubs during transport, and a spring-loaded door that protects the tape; this door automatically opens when the casse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Under
A heterodyne is a signal frequency that is created by combining or mixing two other frequencies using a signal processing technique called ''heterodyning'', which was invented by Canadian inventor-engineer Reginald Fessenden. Heterodyning is used to shift signals from one frequency range into another, and is also involved in the processes of modulation and demodulation. The two input frequencies are combined in a nonlinear signal-processing device such as a vacuum tube, transistor, or diode, usually called a '' mixer''. In the most common application, two signals at frequencies and are mixed, creating two new signals, one at the sum of the two frequencies , and the other at the difference between the two frequencies . The new signal frequencies are called ''heterodynes''. Typically, only one of the heterodynes is required and the other signal is filtered out of the output of the mixer. Heterodyne frequencies are related to the phenomenon of " beats" in acoustics. A major ap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
S-Video
S-Video (also known as separate video, Y/C, and erroneously Super-Video) is an analog video signal format that carries standard-definition video, typically at 525 lines or 625 lines. It encodes video luma and chrominance on two separate channels, achieving higher image quality than composite video which encodes all video information on one channel. It also eliminates several types of visual defects such as dot crawl which commonly occur with composite video. Although it is improved over composite video, S-Video has lower color resolution than component video, which is encoded over three channels. The Atari 800 was the first to introduce separate Chroma/Luma output in late 1979. However, S-Video was not widely adopted until JVC's introduction of the S-VHS (Super-VHS) format in 1987, which is why it is sometimes incorrectly referred to as ''Super-Video''. The S-video format was widely adopted in consumer equipment due to its improvements over composite video. However, it was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CVBS
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 compo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Demodulation
Demodulation is the process of extracting the original information-bearing signal from a carrier wave. A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulated carrier wave. There are many types of modulation, and there are many types of demodulators. The signal output from a demodulator may represent sound (an analog audio signal), images (an analog video signal) or binary data (a digital signal). These terms are traditionally used in connection with radio receivers, but many other systems use many kinds of demodulators. For example, in a modem, which is a contraction of the terms modulator/demodulator, a demodulator is used to extract a serial digital data stream from a carrier signal which is used to carry it through a telephone line, coaxial cable, or optical fiber. History Demodulation was first used in radio receivers. In the wireless telegraphy radio systems us ... [...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] |
Baseband
In telecommunications and signal processing, baseband is the range of frequencies occupied by a signal that has not been modulated to higher frequencies. Baseband signals typically originate from transducers, converting some other variable into an electrical signal. For example, the electronic output of a microphone is a baseband signal that is analogous to the applied voice audio. In conventional analog radio broadcasting, the baseband audio signal is used to modulate an RF carrier signal of a much higher frequency. A baseband signal may have frequency components going all the way down to the DC bias, or at least it will have a high ratio bandwidth. A modulated baseband signal is called a passband signal. This occupies a higher range of frequencies and has a lower ratio and fractional bandwidth. Various uses Baseband signal A ''baseband signal'' or ''lowpass signal'' is a signal that can include frequencies that are very near zero, by comparison with its highest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
