Talking about HD digital movement

The HD movement is mainly composed of a lens, an image sensor (CCD or CMOS device), and an ARM/DSP. The lens gathers the light reflected by the object onto the image sensor, and then the image sensor is photoelectrically converted into a digital video signal and output to the chip. After the chip performs a series of digital image signal processing (ISP) and data compression, the chip transmits to the back end through the network. Decode the display device to realize video preview, video recording, playback and other functions. Through the docking of the movement and the dome of the dome, it is also possible to realize various control of the gimbal, such as up and down rotation, zoom, focus, prefabrication, cruise and many more functions.

The core function modules included in the HD camera movement include image acquisition, image processing, video encoding and decoding, and more. Image sensors that implement image acquisition mainly include low illumination, wide dynamics, BSI and other technologies; image processing (ISP) technology includes 3A (automatic exposure, auto white balance, auto focus), edge enhancement, 3D noise reduction, image scaling, Flip, brightness, chrominance, saturation, contrast adjustment, as well as digital wide dynamics, digital amplification, electronic image stabilization, etc.; image coding and decoding technology mainly includes MPEG4, H.264, MJPEG, multi-stream processing and so on.

We know that HD movements have great in common with digital cameras and DV development technologies. With the popularity of digital cameras and DV applications, these technologies are already very mature. At the same time, the security industry has its own characteristics. For example, it is impossible to keep flashing when the light is dark. A large number of videos cannot be directly saved on the camera. A large number of cameras are distributed in different corners of different scenes instead of being taken by users. In the hands and so on. This requires the image sensor of the high-definition movement to have better performance in low illumination and wide dynamics. Due to the CMOS gradually occupying the mainstream in the HD movement, CMOS has much room for improvement in terms of low illumination, wide dynamics, and BSI. . It has to be mentioned here that Aptina has introduced low-illumination image sensors for security applications. OV has also tried to introduce BSI technology on digital cameras into the security industry. SONY is also gradually paying attention to CMOS and increasing its proportion and strength of research and development. . We can also see that as long as there is room for improvement, everyone will not stop, but try to overcome these problems to seize the commanding heights of the market.

There are several important indicators of the HD movement that need attention, such as power consumption, low illumination, delay, and rich back-end packages.

Power consumption

Whether it is an analog movement or a digital movement, heat is a problem that has to be considered. If the movement is placed in a closed dome, and then a hot infrared panel is placed outside the dome, it will heat up. Electronic components have a working temperature range, usually at 70 ° C. If the operating temperature exceeds 70 ° C, electronic components may burn out. For the ball machine, heat dissipation through the fan and heat insulation is necessary and limited. The heat dissipation depends on where the heat comes from. Therefore, when selecting a million HD camera, you must test the movement of the movement. It's important to look at the heat and see how the power is hot.

Low illumination

In the security industry monitoring, it is impossible to keep flashing when the light is dark. Therefore, there is no low illumination characteristic in millions of HD, and the application is extremely limited. When the light is dim, it is dark, and the pixel is high and loses its meaning. In addition, if the low illumination is not good, the external light increases the power of the infrared light to supplement the light, which will inevitably increase the heat generation. If the temperature is too high for a long time, the life of the camera will be seriously affected.

Delay

As long as it is a digital camera, there are different degrees of delay. Similarly, the 720P HD screen, some camera delays are only 0.11 seconds, while others are as high as 0.4 seconds, 0.7 seconds. Having said that, we may be wondering why the same The resolution has a different delay? Because the digital camera needs to go through three processes, encoding, transmission and decoding display. If you have your own codec algorithm development capability and core underlying technology capabilities, you can optimize the image encoding, network transmission, and image decoding efficiency as much as possible. The performance is optimal and the delay is as short as possible. When the delay is too large, it is very troublesome to control the pan/tilt head. Imagine that the client has issued a command to rotate or stop the pan/tilt, but the image has not changed or is still changing, and the user experience will be very poor. .

The color of the HD movement can be more realistic than the analog camera. During the analog signal transmission, the bright color can not be completely separated, and the brightness signal is doped with the color signal, which causes the picture to be motley, but the HD movement will not. Simulated movement PAL system under 625 scan lines, to 577 lines after blanking, the current limit of up to 540 lines is already the limit, and the digital high-definition movement can reach 800 lines or more, the resolution is up to millions or even 10 million pixels; HD The movement can combine the three lines of video cable, audio cable and control cable, and replace it with one network cable. The digital signal is transmitted. The transmission process is free from electromagnetic interference. The transmission distance through the optical transceiver can be extended to several kilometers. The wiring cost is saved; the image sensor used in the HD movement is also a digital signal, and the processing chip docked with it can directly encode and compress the collected data, independent of external analog-to-digital conversion and encoding compression chip, integration degree Greatly improved, the cost is greatly reduced;

Analog high-line movement applications are divided into two types, one is to use coaxial cable for transmission, and the other is to use network cable for transmission. The latter needs to add a separate processing chip to realize the analog to digital signal, and encode and compress the video. The docking of the hardware and the docking of the software data transmission protocol will greatly increase the cost of the product. The coaxial cable transmission can inherit the wiring of the original analog system. The system composition and device management mode remain unchanged. If the original camera is not high-line, you need to replace the new back-end recording storage device; the preview is not compressed. The video, so it will be very clear, and the playback video will be lost due to compression processing; the coaxial video transmission is analog video signal, not suitable for environments with electromagnetic interference; the transmission distance is very limited, generally not exceeding 100 metres.

The HD-SDI HD movement is very similar to the analog high line. You can also use the wiring of the original analog system, but there will be higher requirements for the back-end recording storage device. If you do not encode the compression, the hard disk space will be consumed. It will be very amazing. If you want to encode and compress, the simultaneous encoding and compression of multi-channel high-definition pictures will have high processing power for the CPU. If you play back the compressed video, the picture quality will be obviously depleted.

Whether it is an analog movement or a digital movement, it is presented in front of the customer with a comprehensive monitoring application management platform that can realize preview screen, recall video, TV wall, alarm warning and other functions. For ordinary users, the platform interface is simple to operate, and high integration is the main requirement. Therefore, whether the high-end movement back-end application is rich is also a very important factor. At present, there is no uniform standard for each manufacturer of high-definition cameras, and ONVIF needs a process to realize seamless connection of various devices. At present, it is mainly relying on powerful engineering companies and manufacturers to promote the docking of various devices and to integrate resources for various heterogeneous systems. In this case, the more various applications of HD movement manufacturers in the market, the more platform software that can be connected to the HD movement, and whether the HD movement supports the ONVIF protocol and is continuously updated. It also determines whether this movement will be able to seamlessly connect with more back-end devices in the future.

With the development of millions of high-definition network cameras, the camera chip realizes more functions, and the integration degree is also higher and higher. As the peripheral devices become less and less, the power consumption will be lower and lower, and the high-definition digital movement There will be more and more applications. In addition to the functions of the traditional smart ball, the high-definition digital movement itself as a digital product, more integrated intelligent functions in the future, such as the number of people, trigger zone, intelligent motion detection, camera tamper detection and other functions.