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Video Compression in a System with Network Cameras and NVRs

In an Internet Protocol (IP) CCTV system, the camera captures raw footage for digitalization and compression, then sends it directly to the NVR for live view, recording, and playback.

Encoding > Decoding > Live View > Recording > Playback

Video Encoding

Transferring uncompressed video data from the camera to the NVR is a large amount of data and doing so will use up all of your network bandwidth and storage space. To significantly reduce the size of video content for efficient transfer, the camera compresses large video footage through the process of encoding. To achieve these levels of compression, the built-in algorithms known as codecs are used. In fact, codec represents a blend of two words: encode and decode. The most common types of codecs are H.264 and H.265 (as well as H.264H and H.265+) can reduce recorded data by as much as 1,000 times.

Video Decoding

Opposite to encoding, the NVR decodes the compressed video stream and then displays it on a TV in its recorded resolution quality. Lorex is known for having the strongest decoding capability NVRs; our NVRs have achieved streaming 4 mainstream channels simultaneously in 4K compared to other NVRs on the market that stream theirs in 1080p substream only. Notably, mainstream is the higher quality stream coming from your NVR, while substream is a secondary and lower quality stream.

4K Mainstream Diagram

Live View Real-time Video

NVRs connect multiple IP cameras over a network to view and manage real-time video streams on one single screen. The camera’s live view can be split between 1 channel view, 4 channel view, 8 channel view and so on (depending on the system’s channel capacity). When the NVR is displaying a multiple split view, it will transmit video through substream. However, the NVR will continue to record video for each channel in the full supported resolution.

Playback Recorded Video

The NVR’s playback screen filters through recorded video, and then plays it back for viewing. Lorex NVRs automatically playback 4 mainstream channels simultaneously in full 4K resolution, while other NVRs on the market playback 4K resolution in 1 mainstream channel only.

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