Understanding Bitrate in CCTV

Installation of CCTV

Understanding Bitrate in CCTV

Bitrate is the measure of the amount of data that is moved from one point to another in a given period of time. It’s measured in “bps”. Number of bits that travel in a unit of time measured in seconds. (bits per second or bps)

A bit (binary digit) is the smallest unit of digital information

1000bits = A kilobit

1000000bits = A megabit

So many times you will come across “96kbps, 128kbps or 2.5mbps” and so much more in different systems.

When we talk about bitrate in CCTV, we are simply talking about the transmission of bits from the camera, or from the DVR to the router and through the internet so as to view remotely.

In other wards you can simply define bitrate as the amount of processing power required to record, live view and play back videos. The higher the bitrate, the more the bandwidth and the more storage space needed.

Bitrate is a result as to why two cameras of the same resolution capturing the same image, will completely output different quality.

Effects of bitrate

Cameras capture real-time images as raw data, which then is processed through the network to be output as video. The more data that can be processed at any given time with higher bitrate, the better video quality you will see.

The Camera’s resolution

The higher the resolution of the camera, the more bitrate it will require for it to deliver a high quality image. You will note that even when all your cameras are recording at 1080p, the quality of image output will always depend on the selected bitrate.

Frame Rate (Fps)

This is referred to as the number of packets a camera can capture in a given period of time. The higher the frame rate, the higher the processing power which is the required bitrate. Also note that more frame rate will require more data to process the footage.

The Compression Rate

Compression reduces huge size images into manageable file sizes which can be easily transmitted over the network. The more the video is compressed, the less data required and the less bandwidth it takes for transmission and hence requires less storage space for storage. But there is also reduction in the image quality output. The higher the compression the lower the bitrate. Videos can be compressed in the following ways H.265, H.264 and H.264+ where H.264+ saves upto 50% bandwidth and storage allocation to give a higher quality surveillance video over the same network. Below is a table to guide you on selecting the right bitrate for your system. It can always change according to your requirements.

Image Resolution Frame Rate (Fps) Average bitrate Maximum bitrate
720p(1280×720) 30 1.8mbps 2.5mbps
25 1.4mbps 2mbps
1080 (1920*1080) 30 2.5mbps 5mbps
25 2mbps 4mbps
4mp (2560*1920 30 3.8mbps 8mbps
25 3.2mbps 6.7mbps


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