VGA input: The VGA interface uses an asymmetrical 15pin connection. Its working principle is to analogically modulate the image (frame) signal stored in digital format in the RAMDAC to an analog high-frequency signal in the RAMDAC, and then output to the projector. Imaging so that the VGA signal at the input (inside the projector) does not have to be scaled by the matrix decoding circuit like other video signals. From the previous video imaging principle, the VGA video transmission process is the shortest, so the VGA interface has many advantages, such as no crosstalk and no circuit synthesis separation loss. DVI input: The DVI interface is mainly used to connect with the computer graphics card with digital display output function to display the RGB signal of the computer. The DVI (Digital Visual Interface) digital display interface is a digital display interface standard established by the Digital Display Working Group (DDWG) established in September 1998 at the Intel Developer Forum. The DVI digital terminal is better than the standard VGA terminal signal. The digital interface ensures that the entire content is transmitted in digital format, ensuring the integrity of the data in the host to monitor transmission process (no interference signal is introduced), and a clearer image can be obtained. Standard video input (RCA): Also known as AV interface, usually paired with white audio interface and yellow video interface, it is usually connected with RCA (commonly known as the lotus head), only need to use the standard with lotus head Connect the AV cable to the corresponding interface. The AV interface achieves separate transmission of audio and video, which avoids degradation of image quality due to mixed audio/video interference, but the AV interface still transmits a luminance/chroma (Y/C) mixed video. The signal still needs the display device to perform light/color separation and chroma decoding before it can be imaged. This process of mixing and then separating will inevitably result in the loss of the color signal, and the chroma signal and the luminance signal will also have a great chance to each other. Interference affects the final output image quality. AV also has a certain vitality, but due to its insurmountable disadvantage of Y/C mixing itself, it cannot be used in some situations where visual limits are sought. S video input: S-Video specifically called Separate Video in English. In order to achieve better video effects, people began to search for a faster, better and sharper video transmission. This is the current S-Video (also known as The two-component video interface), Separate Video means that the Video signal is transmitted separately, that is, the chroma signal C and the luminance signal Y are separated on the basis of the AV interface, and then transmitted in different channels respectively, and it appears and develops. In the late 1990s, a standard 4-core (without sound effects) or an extended 7-core (with sound effects) was usually used. Graphics cards and video equipment with S-Video interfaces (such as analog video capture/editing cards for televisions and quasi-professional monitor TV cards/TV boxes and video projection equipment, etc.) are currently common, compared to AV interfaces because it does not The Y/C mixed transmission then eliminates the need for bright color separation and decoding, and the use of separate transmission channels largely avoids image distortion caused by signal crosstalk in the video equipment, which greatly improves the image quality. Sharpness, but S-Video still mixes the two channels of color difference signals (Cr Cb) into one chroma signal C for transmission and then decodes them in the display device to Cb and Cr for processing. This will still bring some signals. Distortion due to loss (this distortion is small but can still be found when testing under strict broadcast video equipment), and since the mixing of Cr Cb results in a limited bandwidth of the chroma signal, S-Video is already Better but still far from perfection, S-Video is not the best, but consider other factors such as the current market conditions and comprehensive costs It is also the most common video interface. Video color difference input: At present, the YUV YCbCr Y/BY/BY and other markers can be seen on some professional-grade video workstations/editing cards, professional-grade video equipment, or high-end DVD players, although the marking method and the connector shape are different. Different but all refer to the same interface color difference port (also called component video interface). It usually uses two types of labels, YPbPr and YCbCr. The former represents the progressive color difference output, and the latter represents the interlaced 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 the green difference Cg is uniformly ignored during video output and color processing and only retained Y Cr Cb, this is the basic definition of the color difference output. As the S-Video's advanced product color difference output, the chroma signal C of the S-Video transmission is decomposed into the color difference Cr and Cb. This avoids the process of mixing and decoding the two channels of color difference and separates again, and also maintains the maximum of the color channel. Bandwidth is only required to be restored to RGB three primary color signals by an inverse matrix decoding circuit, which minimizes the video signal channel between the video source and the display imaging, and avoids the image caused by the tedious transmission process. Distortion, so the output interface of color difference is the best one among various video output interfaces. BNC port input: The connector usually used for workstation and coaxial cable connection, standard professional video equipment input and output ports. The BNC cable has 5 connectors for receiving red, green, blue, horizontal sync and vertical sync signals. The BNC connector differs from the normal 15-pin D-SUB standard connector by a special display connector. It consists of R, G, B three primary color signals and five independent signal connectors for line synchronization and field synchronization. It is mainly used to connect workstations and other systems that require high scanning frequency. The BNC connector can isolate the video input signal and reduce the interference between the signals. The signal bandwidth is larger than the normal D−SUB, which can achieve the best signal response. RS232C serial port: The full name of RS-232C standard (protocol) is EIA-RS-232C standard, among which EIA (Electronic Industry Association) stands for American Electronics Industry Association, RS (ecommeded standard) stands for recommended standard, 232 is identification number, and C stands for RS232 The latest revision (1969), prior to this, was RS232B, RS232A. It specifies the connection cables and mechanical, electrical characteristics, signal functions and transmission processes. Common physical standards include EIA�RS-232-C, EIA�RS-422-A, EIA�RS-423A, and EIA�RS-485. Only EIA�RS are introduced here. -232-C (232, RS232). 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, and 7 spare and undefined lines. Commonly used only Nine, often used with 25-pin D-SUB ports, with a maximum transfer rate of 20 kbps and a maximum cable length of 15 meters. The RS232C port is used to input computer signals into the control projector. Audio input interface: It can input the audio signal of computer, video recorder, etc., and play through its own speaker.