In the early days of CCTV technology you don’t have much choice but to opt for an analog DVR to record surveillance data. The video quality wasn’t great. Someone must be around to change the video tape when it runs out if recording space. This has made the switch to digital technology an attractive option. While it would have not caused a beginner much headache to purchase an analog CCTV system, choosing a digital one could be somewhat tricky.
As your surveillance camera is expected to run 24/7, there’ll be a huge amount of video data that needs to be recorded. The obvious question is how you’ll be handling the storage of the data. Would you have to fork out a huge amount of cash for data storage? You’ll wonder whether you’ll have enough hard disk space to store your video data. Your worry is justified as an hour of uncompressed video at a resolution of 320 x 240 will take up about 21GB of space.
Uncompressed video of course gives you the best possible quality. However, when it comes to CCTV video, content rather than quality takes preference. Nobody wants to sacrifice a sizeable amount of disk space for the sake of visual quality.
Is there a way of minimizing disk usage for your CCTV video without sacrificing quality? There is if you use an appropriate compression format. Among the compression formats available for CCTV compression are MJPEG, MPEG and Wavelet, which is a proprietary compression format not in popular use.
MJPEG or Motion JPEG is a lossless compression format which creates video data from a series of JPEG images. While quality is high, it requires a sizeable amount of disk space for storage.
MPEG on the other hand comes in two compression formats. MPEG1 is a low-quality compression format which outputs video at about 15 frames per second. MPEG 2, on the other hand promises high quality video but takes up much storage space. There are special hardware requirements for MPEG 2 which can’t be served by your PC.
MPEG 4 Part 2 (MP4) used by such codecs as Divx and Xvid is also common. This promises better quality than MPEG 1 and less storage space than MPEG 2.
MP4 used to be a popular CCTV compression format until the emergence of H264 or also known as AVC (Advanced Video Coding). H264 compression promises impressive video quality despite a significant reduction in video file size.
It has a file size 80 per cent smaller than MJPEG compression. What’s more it takes up 50 per cent less storage space compared to MP4 compression. Thus by utilizing the H264 compression, CCTV users could save on hard disk storage while enjoying superb video quality. So, instead of getting only one hour of uncompressed video for a space of 21GB, you get up to 80 hours of video if the H264 compression is used.
If you’re in the market for a DVR for your CCTV system, ensure that it supports H264 compression so that you could save on storage space without compromising video quality.