By PURPLELEC | 13 December 2023 | 0 Comments
What are the video interfaces?
1. Radio frequency
The antenna and the analog closed-circuit connection to the TV use a radio frequency (RF) interface. As the most common video connection method, it can transmit analog video and audio signals simultaneously. The RF interface transmits mixed and encoded signals of video and audio. The circuit of the display device performs a series of separation, decoding and output imaging of the mixed encoded signals. Due to the need for mixed encoding of video and audio, the signals will interfere with each other, so its image output quality is the worst among all interfaces. Cable and satellite TV reception equipment also commonly use RF connections, but in this case they transmit digital signals.
2. Composite video
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.
It is a video interface that separates audio and video. It is generally composed of three independent RCA plugs (also called plum blossom interface and RCA interface). The V interface is connected to the mixed video signal and is a yellow plug; the L interface is connected to the left channel sound. The signal is a white jack; the R interface is connected to the right channel sound signal and is a red jack.
3. S-Video interface
The S interface is also a very common interface. Its full name is Separate Video, also known as SUPER VIDEO. The S-Video connection specification is a specification developed by the Japanese. S refers to "SEPARATE", which separates brightness and chroma into output, avoiding mutual interference between brightness and chroma when mixing video signals. The S interface is actually a five-core interface, consisting of two channels of brightness signals, two channels of video chrominance signals, and a common shielded ground wire.
4. YPbPr/YCbCr color difference interface
The color difference interface is based on the S interface and sends the blue difference (b) and red difference (r) in the chroma (C) signal separately. Its resolution can reach more than 600 lines. It usually uses two logos: YPbPr and YCbCr. The former represents progressive scanning color difference output, and the latter represents interlaced scanning color difference output. Many TV products now rely on component input to improve input signal quality, and through the component interface, multiple levels of signals can be input, from the most basic 480i to 480p with frequency doubling scanning, even 720p, 1080i, etc. Only through component input can the signal be transmitted to the TV.
5. VGA interface
The VGA interface is also called the D-Sub interface. The VGA interface is a D-type interface with a total of 15 pins, divided into three rows of five in each row. The VGA interface is the most widely used interface type on graphics cards, and most graphics cards have this interface. A mini stereo or home theater has a VGA interface that can be easily connected to a computer monitor and the computer monitor can be used to display images.
6. DVI interface
DVI (Digital Visual Interface) interface and VGA are the most commonly used interfaces in computers. Unlike VGA, DVI can transmit digital signals without digital-to-analog conversion, so the picture quality is very high. Currently, many high-definition TVs also provide DVI interfaces. It should be noted that there are many specifications for DVI interfaces, the common ones are DVI-D (Digital) and DVI-I (Intergrated). DVI-D can only transmit digital signals, and you can use it to connect graphics cards and flat-screen TVs. DVI-I can convert between DVI-D and VGA.
7. SDI interface
The SDI interface is a "digital component serial interface". A serial interface is an interface that sequentially transmits individual bits of data and corresponding data through a single channel. Due to the high data rate of serial digital signals, they must be processed before transmission. Scrambling non-return-to-zero inversion (NRZI) is used to replace early block coding. The standards are SMPTE-259M and EBU-Tech-3267. The standards include digital composite and digital component signals including digital audio. Before transmission, the original data stream is scrambled and converted into NRZI code to ensure that the original data is reliably restored at the receiving end. In this way, the digital serial interface can be conceptually understood as a baseband signal modulation. The SDI interface can pass 270Mb/s serial digital component signals. For 16:9 format images, it should be able to transmit 360Mb/s signals.
8. HDMI interface
HDMI (High Definition Multimedia Interface), like DVI, transmits all-digital signals. The difference is that the HDMI interface can not only transmit high-definition digital video signals, but also transmit high-quality audio signals at the same time. At the same time, the functions are the same as those of the radio frequency interface, but due to the use of fully digital signal transmission, there will be no poor picture quality like the radio frequency interface.
9. DisplayPort interface
DisplayPort is a display interface released by the Video Electronics Standards Association (VESA). As the successor to the DVI interface, DisplayPort will transmit video signals while adding support for high-definition audio signal transmission, while supporting higher resolutions and refresh rates.
By design, DisplayPort supports both external display connections and built-in display connections. VESA hopes that notebook manufacturers will not only use DisplayPort to connect independent monitors, but also use it to directly connect LCD screens and motherboards to facilitate notebook upgrades. For this reason, the DisplayPort interface is also designed to be very compact, which is convenient for notebook use and allows the graphics card to be configured with multiple interfaces.
10. IEEE1394 interface
IEEE 1394 is also called FireWire or iLink. It can transmit digital video and audio and machine control signals. It has high bandwidth and is very stable. Usually it is mainly used to connect digital cameras, DVD recorders and other equipment. There are two types of IEEE 1394 interfaces: 6-pin hexagonal interface and 4-pin small quad interface. The 6-pin hex connector can provide power to the connected device, while the 4-pin quad connector cannot.
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