These days, a friend has been discussing the difference between VGA and HDMI interface. Before this, we have a preliminary understanding of the transmission distance between HDMI and VGA. With the development of technology, VGA and HDMI interfaces have also been updated. In this issue, we have Learn more about the differences and features of VGA, DVI, and HDMI.
First, some misunderstandings about VGA, DVI, HDMI
Misunderstanding 1: HDMI is HD, VGA is not.
These three are not equivalent, HDMI and VGA are both signal transmission methods, and HD refers to a video resolution. HDMI supports HD, and VGA also supports it. HDMI currently supports 3840*2160 resolution and 50FPS, 60fps frame rate HD format, VGA supports various resolutions from 640*480 up to 2560*1600, but VGA is very susceptible to interference from other signals, so HD resolution appears A bit imaginary, in order to avoid interference of the picture, below the 1920*1080P resolution, you can use the VGA interface.
Misunderstanding 2: HDMI bandwidth is high, VGA bandwidth is low. So HDMI is better than VGA.
The bandwidth of HDMI is the digital signal bandwidth, and VGA is the analog signal bandwidth, which is the transmission method of two different technologies. If you want to compare, you can compare the same resolution, such as HD, HDMI requires 2.2GHz bandwidth, and VGA only needs 172MHz bandwidth. But high bandwidth does not mean that HDMI transmits more video signals, just because of the different transmission technologies.
Misunderstanding 3: HDMI signal does not require digital-to-analog conversion, no signal loss; VGA signal requires digital-to-analog conversion, and signal loss is large.
Although HDMI does not require digital analog conversion, it still has to undergo digital to digital conversion. No matter what kind of conversion process it is, what is converted into it is, after all, a description of the analog electrical signal. Their relationship is as follows:
The signal described by the digital signal is composed of one point, which is inconsistent in the change of the signal, and the change of the analog signal is a continuous curve, so the simulated signal gives a better sense of reality. When a digital signal is converted to an analog signal, the direct output is also a point (the sampling point of the digital signal), and the undescribed part is automatically generated by the conversion program (similar to the 3D anti-aliasing technique) to form a continuous Analog signal waveform. When an analog signal is converted to a digital signal, the continuous analog signal is converted into a digital signal describing a point, and the signal becomes incomplete. From this process, the conversion of digital signals to analog signals is enhanced rather than lost, and analog signals are converted to digital signals with loss.
In the VGA transmission process, the signal loss of the VGA to LVDS driving LCD panel can be neglected, because in the case of the same digital sampling rate at the front and rear ends, these lost signals are originally (when the digital signal is converted into an analog signal) the program automatically The part that is filled is not the loss of the original signal of the digital signal source. Figure:
Second, VGA, DVI, HDMI features
VGA
VGA (Video Graphics Array) also has a name called D-Sub. It is an analog signal and can only transmit video signals. The VGA interface has a total of 15 pins, divided into 3 rows and 5 holes per row. It is the most widely used interface type on the graphics card. Most graphics cards have such interfaces. It transmits red, green, and blue analog signals as well as synchronization signals (horizontal and vertical signals). Use VGA to connect the device, the cable length should not exceed 10 meters, and pay attention to whether the connector is installed firmly, otherwise it may cause ghosting in the image, and VGA can only transmit
VGA supports simultaneous display of 16 colors or 256 shades of gray at a higher resolution of 640 x 480, while simultaneously displaying 256 colors at 320 x 240 resolution.
particular
1. It is the transmission of analog signals. The higher the resolution of the display, the more blurred the picture will be. A general analog signal will show significant errors when it exceeds 1280 x 1024 resolution.
2. Because it is analog information, the signal is extremely susceptible to interference.
3. Can't communicate audio.
4, generally do not add amplifiers and converters in about 30 meters, plus amplifiers and amplifiers can be up to 150 meters.
DVI
DVI is a digital video interface, which is a technology for transmitting digital signals at high speed, and is no longer digital-to-analog. There are several specifications for the DVI interface. Common ones are DVI-A, DVI-D, and DVI-I. DVI video transmission avoids the analog-to-digital conversion process of the transmitting end (usually the graphics card) and the analog-to-digital conversion process of the receiving end (usually the LCD display) during the transmission of the analog video signal, and also avoids the noise interference during the transmission of the analog signal. Problem, so the image is not lost.
Features:
1. Digital signal avoids the analog/digital conversion process, the signal is not attenuated, and the color is purer and more realistic.
2. Only the video signal is transmitted, and the audio signal is not transmitted.
3, support a variety of formats, including 1920 * 1080 all HD formats.
4, the general transmission of about 15 meters.
HDMI
High Definition Multimedia Interface (HDMI) is a digital video/audio interface technology. It is a dedicated digital interface suitable for image transmission. It can transmit audio and video signals at the same time. The maximum data transmission speed is 5Gbps. . There is no need to perform digital/analog or analog/digital conversion before signal transmission.
HDMI2.0b features
1. Support (HDR) high dynamic range video transmission
2. Up to 18Gbps broadband
3. The resolution is increased to 4K, 3840*2160 resolution and 50FPS, 60fps frame rate.
4. Up to 32 audio channels for an immersive multidimensional audio experience.
5. Up to 1536khz audio sample rate, providing the best audio fidelity.
6. Simultaneously transfer dual video streams, allowing different users to watch different videos on the same screen.
7. Simultaneously transfer multiple audio streams to multiple users (up to 4)
8. Provide a new experience of wide-angle cinema 21:9 aspect ratio
9. Dynamic automatic sound and picture synchronization
10.CEC extension provides more extended control for a single remote control to control multiple consumer electronics products
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