AV motherboard PCB prototype assembly

AV format is also called AV interface, short for audio and video. The full name of AV port is composite video connector, which is a port commonly used by home audio-visual equipment to transmit analog video such as NTSC, PAL, SECAM, ฯลฯ. AV port is generally a yellow RCA port, and the red and white RCA ports are used to transmit audio. European TVs usually use SCART ports instead of RCA ports, but SCART is designed to carry RGB signals with better picture quality than YUV, so it is also used to connect monitors, video game consoles or DVD players.

Introduction to composite video

Composite video, full name: composite video broadcast signal or composite video blanking and synchronization, is a format in which analog TV program (picture) signals are combined with sound signals and modulated to the radio frequency carrier. Among them, the V interface connects the mixed video signal, which is a yellow socket; the L interface connects the left channel sound signal, which is a white socket. The R interface connects the right channel sound signal, which is a red socket. There are two types of terminals for composite video interfaces: RCA terminals and BNC terminals. The RCA terminal is the so-called lotus head rosette, and the BNC terminal is the BNC head rosette. RCA terminals can be used for composite video interfaces and audio interfaces. If used for audio interfaces, they are usually called 3.5 lotus heads (sockets). Composite video, also known as baseband video or RCA video, is the traditional method of transmitting image data in the National Television Standards Committee (NTSC) television signal of the United States. It transmits data in an analog waveform.

Composite video interface
Composite video interface: Composite video signal is defined as a single-channel analog signal including brightness and chrominance, นั่นคือ, a video signal after the audio is separated from the complete television signal. At this time, the chrominance signal is still interlaced with the high end of the brightness signal. Because the brightness and chrominance of composite video are interlaced, it is difficult to restore completely consistent colors when replaying the signal. This signal can generally be input or output to a home video recorder via a cable. Its signal bandwidth is relatively narrow, generally with a resolution of only about 240 horizontal lines. Early televisions only had antenna input ports, while newer televisions were equipped with composite video input and output ports (VideoIn, Video Out), which can directly input and output demodulated video signals. Video signals do not contain high-frequency components and are relatively simple to process, so computer graphics cards generally use video input ports to obtain video signals.

Composite video interface and CVBS interface
Abbreviation for “color, video, blank and sync”, “composite video baseband signal”, “composite video burst signal” or “composite video with burst sync”. CVBS is a widely used standard, also known as baseband video or RCA video, and is a traditional image data transmission method of the National Television System Committee (NTSC) television signal, which transmits data in an analog waveform. It is a format that combines analog TV program (picture) signals with sound signals and modulates them onto a radio frequency carrier. AV=AUDIO+VIDEO, in fact, VIDEO is CVBS

CVBS connection and RCA interface
Composite video signal (CVBS) interface, also known as RCA interface. RCA is the abbreviation of Radio Corporation of AmerICa, because the RCA connector was invented by this company. RCA is commonly known as lotus socket, also known as AV terminal, also known as AV interface. It is usually a pair of white audio interface and yellow video interface. Generally, RCA (commonly known as lotus head) connection is adopted. Connect the standard AV cable of the pan/tilt to the corresponding interface. RCA connector is by far the most common type of audio/video terminal. RCA audio terminals are usually marked in pairs with different colors: red for the right channel and black or white for the left channel. พูดโดยทั่วไป, an RCA stereo audio cable is a set of left and right channels, each of which is a line in appearance. The commonly paired audio interfaces right channel (red) left channel (white) and video interface (yellow) composite video (Composite) usually use yellow RCA (Lotus socket) connectors. “Composite” refers to an analog signal that transmits brightness and chrominance signals on the same channel, but if the TV cannot separate the two signals well, ghosting will occur. Audio interfaces and video interfaces are used in pairs, generally white audio interfaces and yellow video interfaces, using RCA (Lotus head) connection. When using, you only need to connect the standard AV cable with a Lotus head to the corresponding interface to use it. Can.

Composite video connection and AV interface
The composite video interface, also called AV interface or Video interface, is the most common video interface at present. Almost all TVs and DVD players have this interface. AV composite (Composite) video interface, นั่นคือ, analog interface, is a video interface that separates audio and video. It is generally composed of three independent RCA plugs (also called plum blossom interface, RCA interface), yellow, white and red. Among them, the V interface connects the mixed video signal, which is a yellow socket; the L interface connects the left channel sound signal, which is a white socket; the R interface connects the right channel sound signal, which is a red socket. The output port is also equipped with audio input and output ports (AudioIn, AudioOut) for synchronous transmission of audio. ดังนั้น, sometimes the composite video interface is also called AV (AudioVideo) interface. The AV interface realizes the separation transmission of audio and video, avoiding the interference of audio and video mixing leading to the degradation of picture quality, but because the AV interface still transmits a brightness/chroma (Y/C) mixed video signal, it needs to be separated by brightness/color and decoded by chroma before imaging. In the process of mixing first and then separating, the signal will inevitably be lost or distorted, and the chroma signal and the brightness signal will also have a great chance to interfere with each other. . Due to the inherent technical defects of the brightness/chroma (Y/C) mixed video signal processing method, the application of the AV video interface has great restrictions and usage restrictions.