With the arrival of the era of high-definition surveillance, the غير مجاز مي باشدt of the entire security video surveillance system began to rise significantly. Among these, not only is the غير مجاز مي باشدt of front-end HD cameras increased, but the غير مجاز مي باشدt of back-end storage devices has risen dramatically as image clarity has increased from SD to HD. The data shows that when using traditional DVR and NVR solutions, the غير مجاز مي باشدt of storage devices in the entire video surveillance system is roughly 15% to 30%; while in digital network high-definition video surveillance systems, the غير مجاز مي باشدt of storage devices in the entire system is Will rise to 50% to 70%.
This is not a sensational statement. Taking the HD basic 720P effect as an example, the normal hard disk capacity required for video surveillance is about 4G~8G/hour. For economic reasons, reducing the hourly video recording can be reduced to about 3GB. capacity. Taking this as an example, eight-way monitoring is about 17T capacity by one month calculation. According to the relevant regulations, surveillance video in public places needs to be kept for at least one month (30 days) or longer, and in some places for a longer period of time, the mass data storage problems caused by this can be imagined.
So, what can be done to reduce غير مجاز مي باشدts on the basis of expanding storage? The following are some common ways to reduce storage space for your reference.
Choose the right codec
If you upgrade the encoding format from MJPEG to H.264, you can save more than 50% of the storage space. Because of this, more and more end-users are beginning to upgrade their data formats from MJPEG and MPEG-4 to H.264, allowing compressed video to take up less space while maintaining the same video quality as MPEG-4.
A typical frame (R frame) is selected in the video sequence, and the end user can choose to store only R frames. By using R frames and compressing video streams in H.264 format, video streams can be generated with lower bandwidth and more efficiently. This situation is useful for most cameras. For example, for a fixed camera that monitors a few moving targets at an airport terminal or for a continuously rotating camera like PTZ, the resulting R frame increases.
In some cases, the video quality provided by the H.264 compression method is only better than the video quality provided by the MJPEG compression method at the border, but because the H.264 compression method occupies lower bandwidth. Therefore, recording video data takes up less storage space.
In general, in most monitoring systems, H.264 is an efficient codec in terms of reducing bandwidth and storage space.
Idle time to reduce the recording rate
We all know that in places like office buildings and schools, there are few people appearing at night, but the cameras are working as usual. The recorded videos do not have any effect at all and they also occupy storage space. Therefore, we can consider lowering the recording rate during periods when there are few moving targets by controlling the recording rate. For example, 15 frames per second may occupy a large amount of storage space. At this time, it is possible to use 2 to 3 frames per second, or even 1 frame per second. Rate recording, the end user can save up to 80% of the recording space.
However, although there are few pedestrians in the building during the night, many meeting rooms are not used during most of the time. If these occasions have been recording video at a low rate, what if there is an alarm? We can consider adding basic intelligent motion analysis to the monitoring system. If there is a moving target, the recording frame rate will return to the normal rate. When the moving target disappears, the recording rate will return to 2 to 3 frames per second. As a result, it not only reduces the storage space, but also can play the role of monitoring alarms.
Do not record unwanted content
The above method is mainly for the monitoring area is mainly static type, the number of monitoring targets is not much, but if for the road, elevator and other places where people come and go, we cannot use the above method to reduce the recording rate. In this case, is there a feasible solution?
At this time, we can consider adding a basic motion analysis software package to the monitoring system. For some moving objects, we do not need to record their videos. For example, when a car drives down a road, we don't need to record the whereabouts of the car. When the trees sway in the wind, they don't need to record; if this happens, they are also recorded, like the surveillance perimeter. It is necessary to keep recording, so the storage space consumed can be imagined.
According to relevant statistics, for some cameras, the areas that are not required to monitor moving targets in the surveillance area can save up to 50% of storage space.
Fixed rate decimation frame storage technology
According to the current mainstream compression method, the required space for surveillance video storage is as follows:
H.264 compression method: HAFLD1 resolution, real-time 25 frames, 300M/hour/road;
H.264 compression method: CIF clarity, real-time 25 frames, 200M/hour/road;
Based on the above data, we can basically estimate the storage space required for all the video surveillance images. For example, a bank needs a 1-channel D1 video surveillance system, 7*24 hours of monitoring, data can be covered in 3 months, then the total capacity needs 1.1TB.
If the video we already have is not as important as the new video, we can reduce the recording frame rate of the old video. This can greatly reduce the need for old video storage space. At the same time, old video can still be used as evidence if needed.
Using fixed-rate decimation frame storage technology, such as 25-frame/s video files stored within one month, can be reduced to 15 frames/s without affecting video recording information, which can also greatly save storage. space.
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