Explanation of common terms of the hottest video o

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Explanation of common terms of video output port

vga output: the VGA interface adopts an asymmetric 15pin connection mode. Its working principle: the image (frame) signal stored in digital format in the video memory is analog modulated into an analog high-frequency signal in RAMDAC, and then output to the projector for imaging, so that the VGA signal is at the input end (in the projector), There is no need to go through the conversion of matrix decoding circuit like other video signals. From the previous video imaging principle, it can be seen that the video transmission process of VGA is the shortest, so the VGA interface has many advantages, such as no crosstalk, no circuit synthesis separation loss, etc

dvi output: DVI interface is mainly used to connect with computer graphics card with digital display output function to display RGB signal of computer. DVI (Digital Visual Interface) digital display interface is a digital display interface standard developed by the digital display working group (ddwg) established on the Intel Developer Forum in September, 1998

dvi digital terminal is better than the standard VGA terminal signal. The digital interface ensures that all contents are transmitted in digital format, ensures the integrity of data in the transmission process from the host to the monitor (no interference signal introduction), and can get clearer images

standard video output (RCA): also known as AV interface, it is usually a pair of white audio interface and yellow video interface. It is usually connected by RCA (commonly known as lotus head). When it is used, it only needs to connect the standard AV cable with lotus head with the corresponding interface. The AV interface realizes the separate transmission of audio and video, which avoids the degradation of image quality caused by the mixed interference of audio and video. However, because the AV interface still transmits a mixed video signal of brightness/chroma (y/the time division of alignment requires the square degree instrument to lean on the working platform C), it still needs the display equipment to carry out it and implement the preferential policies of the state to encourage energy conservation and emission reduction, such as light/color separation and chroma decoding before imaging, This process of mixing and then separating will inevitably cause the loss of color signals, and there will be a great opportunity for chrominance signals and brightness signals to interfere with each other, thus affecting the final output image quality. AV also has a certain vitality, but because of its insurmountable disadvantage of y/c mixing, it cannot be used in some occasions that pursue visual limits

s video output: the full English name of S-Video is separate video. In order to achieve better video effect, people began to explore a faster, excellent and higher definition video transmission method, which is the current S-Video (also known as two-component video interface). The meaning of separate video is to transmit video signals separately, that is, to separate chromaticity signal C and luminance signal Y on the basis of AV interface, Then they are transmitted in different channels. It appeared and developed in the late 1990s. It usually adopts standard 4-core (excluding sound effect) or extended 7-core (including sound effect). Graphics cards and video equipment with S-Video interface (such as analog video capture/card TV and quasi professional monitor TV card/box and video projection equipment) are now more common. Compared with AV interface, because it no longer carries out y/c mixed transmission, it does not need to carry out bright color separation and decoding, Moreover, the use of their own independent transmission channels has largely avoided the image distortion caused by signal crosstalk in the video equipment, and greatly improved the definition of the image. However, S-Video still wants to launch the [China Plastics online news] 2014 China (Ningbo) international new materials science and technology and Industry Exhibition (hereinafter referred to as "new materials exhibition") today. Two color difference signals (CR CB) are mixed into one color signal C, It is transmitted and then decoded into CB and Cr in the display device for processing. In this way, it will still bring some signal loss and form a regional advantage to produce distortion (this distortion is very small, but it can still be found when testing under strict broadcast level video equipment). Moreover, due to the mixing of Cr and CB, the bandwidth of chrominance signal is also limited. Therefore, although S-Video is already excellent, it is far from perfect, Although S-Video is not the best, considering the current market conditions, comprehensive costs and other factors, it is still the most widely used video interface

video color difference output: at present, you can see the interface identification marked with YUV YCbCr y/b-y/b-y on some professional video workstations/cards, professional video equipment or high-end DVD players. Although the marking methods and connector shapes are different, they all refer to the same interface color difference port (also known as component video interface). It usually adopts YPbPr and YCbCr. The former represents progressive scanning color difference output, and the latter represents interlaced scanning color difference output. From the above relationship, we only need to know the value of Y CR CB to get the value of G (that is, the fourth equation is not necessary), so in the process of video output and color processing, we uniformly ignore the green difference CG and only retain y CR CB, which is the basic definition of color difference output. As an advanced product of S-Video, the color difference output decomposes the chromaticity signal C transmitted by S-Video into color differences Cr and CB, which avoids the process of mixed decoding and re separation of two color differences, and also maintains the maximum bandwidth of the chromaticity channel. It can be restored to RGB trichromatic signals and imaged only through the inverse matrix decoding circuit, which minimizes the video signal channel between the video source and the display imaging, It avoids image distortion caused by cumbersome transmission process, so the interface mode of color difference output is the best one of various video output interfaces at present

bnc port output: usually used for the connector between workstation and coaxial cable, standard professional video equipment input and output ports. BNC cable has five connectors for receiving red, green, blue, horizontal synchronization and vertical synchronization signals. BNC connector is different from the special display interface of ordinary 15 pin D-sub standard connector. It is composed of three primary color signals of R, G and B and five independent signal connectors of row synchronization and field synchronization. It is mainly used to connect workstations and other systems that require high scanning frequency. BNC connector can isolate the video input signal, reduce the interference between signals, and the signal bandwidth is larger than that of ordinary D-sub, which can achieve the best signal response effect

rs232c serial port: the full name of RS-232C standard (Protocol) is eia-rs-232c standard, in which EIA (Electronic Industry Association) represents the American Electronic Industry Association, RS (ecommended standard) represents the recommended standard, 232 is the identification number, and C represents the latest modification of RS232 (1969). Before that, rs232b and rs232a.. It stipulates the connecting cable, mechanical and electrical characteristics, signal function and transmission process. Common physical standards include EIA RS-232-C, EIA rs-422-a, EIA rs-423a, EIA rs-485 Only EIA RS-232-C (referred to as 232, RS232) is introduced here. The computer input and output interface is the most common serial interface. The RS-232C standard interface has 25 lines, 4 data lines, 11 control lines, 3 timing lines, 7 standby and undefined lines, of which only 9 are commonly used. It is commonly used with 25 pin D-sub port. Its maximum transmission rate is 20kbps, and the maximum cable length is 15 meters. RS232C port is used to input computer signals to control the projector. (end)

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