Video capture card analysis of common problems, let’s have a look!

1、 What is the main difference between soft compression and hard compression?

A: the difference between soft compression and hard compression mainly lies in who executes the compression algorithm. If the compression algorithm is calculated by CPU, it is soft compression. If the compression algorithm is calculated by DSP or other compression chips on DVR card, it is hard compression.

2、 How to treat the CPU utilization of soft card?

A: due to the above reasons, soft compression cards need more CPU resources than hard compression cards. However, the main functions of CPU and DSP are computing. Idle CPU resources and using high-cost DSP means that the utilization efficiency of CPU is low. In many developed countries, soft compression applications are in the majority.

Of course, it is not that the higher the CPU utilization is, the better. If the CPU resource utilization exceeds a certain limit, the system will be unstable or even crash. There is a balance point in the middle. The jy-2000 monitoring software independently developed by our company controls the maximum utilization rate of system resources within 80%. When this value is exceeded because the configuration is lower than the system requirements, the system will automatically reduce the number of working paths, so as to avoid crash and ensure the stability of the system. The higher the CPU frequency, the lower the occupancy rate.

3、 What are the characteristics of the PCI Express interface standard?

A: 1. Compared with the traditional PCI bus, the point-to-point connection mode, pciexpress has a fundamental innovation in the working mode – using the point-to-point bus connection mode. We know that the traditional PCI bus works in the way of exclusive bandwidth. There can only be one device on the PCI bus for communication at any time. Once the number of devices on the PCI bus increases, the problem of bus control contention will seriously restrict the performance of PCI devices.

The pciexpress bus adopts a point-to-point connection mode. Each device establishes its own transmission channel when it is required to transmit data. For other devices, this channel is closed and each channel does not interfere with each other, so the efficiency of data transmission is greatly improved.

2. Serial transmission mode the data transmission of pciexpress is serial mode, using “voltage differential signal transmission”, that is, two lines, with the voltage difference between each other as the representation of logic “0” and “1”. Every two lines form a lane. The theoretical transmission rate of each path is 2.5gbit/s. In practice, there can be two transmission paths, which are divided into uplink and downlink. In this way, pciexpress can work in duplex state and provide higher transmission rate and quality.

3. High speed transmission pciexpress is divided into x1, X2, x4, X8, x16 and X32. X1 is the shortest in shape, and the longer it goes up. They are downward compatible. Pciexpressx16 has 5GB / S (2.5Gb) in a single channel × 16 / 8 = 5GB / s) bandwidth, but due to 8B / 10B coding, the effective bandwidth is actually 4GB / S (deducting 20% of the embedded clock signal).

Similarly, the “pciexpressx1” single channel instead of the current PCI slot should have a bandwidth of 250MB / s, while the bandwidth of the traditional PCI bus is 133mb / s. The high bandwidth of PCI Express can achieve higher data throughput.

4. Hot plug support (must be supported by the motherboard) the data transmission distance of pciexpress bus is up to 3m, so that each hardware subsystem can be separated from each other in space and connected only by cable. It supports hot plug function and can monitor all access devices in real time. In this way, hardware manufacturers can design components whose shape and size meet the modular requirements. When users need to expand and upgrade hardware, they only need to unplug the old and plug in the new without shutting down.

5. Good compatibility. In addition, pciexpress bus is also compatible with PCI specification at the software level. It can be used without updating the operating system and BIOS. In the future, mainboards using pciexpress bus can still support PCI slots, and expansion cards with various PCI interfaces can operate normally in low bandwidth mode, which provides the basis for the rapid popularization of pciexpress without facing the embarrassment of waiting for software.

4、 What are the advantages of video soft compression card based on PCI Express interface?

A: the excellent data throughput capacity of PCI Express interface makes a stable video recording system with large number of channels, high image quality and full real-time for video soft compression card, which breaks the bottleneck of insufficient data transmission speed of traditional PCI interface (at present, jy-5008 (a) can support up to 32 channels of audio and video full real-time, and it is recommended to use this card for more than 20 channels). At the same time, the Intel 945G series motherboard with PCI Express interface, which is becoming more and more popular and cheap, also provides a good platform for its application and popularization.

5、 What if the number of PCI Express interfaces on the motherboard is small?

A: at present, the number of PCI Express interfaces in the mainboard with integrated graphics card of Intel 945 chipset is usually 1 ~ 3, but the main of this series generally also has an independent graphics card slot of PCI express16x. Because the PCI Express interface standard is compatible from top to bottom, Therefore, the pci-expressx16 independent graphics card slot can also be used as a video soft compression card based on PCI Express interface.

At the same time, because pciexpress is also compatible with PCI specification at the software level, the video soft compression card jy-5008 (a) of PCI Express interface can be mixed with the video compression cards jy-4004 (a) and jy-4008 (a) of the same series of ordinary PCI interface, so as to obtain the most reasonable solution.

6、 How do I know the external (public) IP address of my monitoring host?

A: log in to the home page of our company’s website on the monitoring host, and a line displayed in the middle of the screen: “your current IP is x.x.x.x”, which is the external (public) network IP address of your monitoring host.

7、 What factors are related to the quality and stability of DVR image?

A: 1. Surveillance camera: the selection of CCD of surveillance camera directly affects the image quality; The circuit design of the movement board is unreasonable, which may produce color deviation, noise, mosaic and other phenomena. For the monitoring camera with infrared night vision function, the high working temperature of its infrared light board will also interfere with the circuit of the movement board, and even burn the lamp; If the output voltage of the monitoring camera is too high (commonly known as charged), it will not only burn the camera itself, but also the video card. It is recommended to choose a monitoring camera with excellent quality.

2. Video chips used in the acquisition card: different video chips have different performance abilities for image processing. The common ones are: conexantfusion878a, with good definition and slightly poor color; Techwelltw6800 / 6802 has good non real-time performance, and its definition and color performance are general; Philips saa7130 / 7134 has good image color and real-time performance, and the overall performance is relatively balanced. It was widely used in TV cards, TV boxes and other products before.

3. Circuit design of acquisition card: the quality of circuit design and the selection of components will directly affect the stability of video card, especially for perennial equipment such as surveillance video. The performance of low-quality components will decline significantly when they work for a certain period of time. For example: capacitance, crystal oscillator, etc.

4. Overall working speed of the host: in addition to the familiar CPU, memory, graphics card, etc., it also includes the system bus speed of the motherboard, the socket interface speed, the working speed of the north south bridge chipset, the power supply power of the host, etc., which will affect the operation of the DVR system.

5. Software design: a mature and stable software design with high execution efficiency, less resource occupation is also an important guarantee for the long-term and stable operation of DVR.

Responsible editor: CT

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