By PURPLELEC | 17 June 2024 | 0 Comments
Ana-log AV Interface Introduction
Composite video signal is also the common AV video signal, which has a wide range of applications. In today's era of high-definition popularization, analog AV interface is still widely used. For example, set-top boxes, DVDs, TVs, cameras, etc. are equipped with analog AV interfaces. It is called a composite port because it transmits composite video signals.
The composite AV interface is composed of three interfaces, namely red, yellow and white. Many users are not clear about the functions of these three jacks, and what is the difference between the AV interface and other mainstream video signal interfaces?
What does the AV interface consist of?
Since it is a composite port, what are its components? It is divided into 3 lines in total, namely: audio interface (red and white lines, forming left and right channels) and video interface (yellow). Such a signal transmission mode can separate video and audio for transmission, which can minimize the mutual influence between the two signals. See the figure below for specific interfaces and functions:
Composite video interfaces and related wires are very common. After the composite video signal Av port is output, it passes through the AV transmission cable (as shown above). At this time, it is still a video signal (YUV) that mixes brightness and chrominance. Y represents the brightness of the image, and the color data is carried between the U signal and the V signal. Therefore, the display device that is finally connected must perform brightness and color separation, then decode, and finally output the image. This series of processes has an impact on the video quality, so the current high-definition video playback has basically abandoned the AV interface.
What is the difference between the AV interface and other interfaces?
1. HDMI interface
The common HDMI interface can transmit audio and video signals without compression, and can provide up to 5Gbps of data transmission bandwidth at most. The video picture is clear and stable. The biggest advantage is that an HDMI transmission line can replace complex cables. Compared with other analog signal interfaces such as AV, it does not need to undergo digital/analog conversion.
2. VGA interface
Speaking of the VGA interface, you can immediately think of the D-shaped 15-pin hole on the computer host. Like the AV interface, it is also an analog signal interface. After digital/analog conversion, it can output the three primary color signals of R, G, and B and the line and field synchronization signals through the VGA cable. Compared with the digital interface, the effect is worse, but compared with the AV interface, the effect of VGA is better, because the AV signal transmission can only be imaged through brightness/color separation and chroma decoding.
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