When you start to research which surveillance camera is best for your home or workplace you will see ‘bitrate’ pop up over and over.
What is ‘bitrate’ and why does it matter?
Put simply, bitrate in CCTV is the amount of processing power required to record and play back video. The bitrate determines whether your camera’s processor can keep up the image quality in video playback.
Video quality is measured by the bitrate, like a still image is measured by the resolution.
Let’s get technical for a second: a bit (or binary digit) is the smallest unit of digital information. 1,000 bits make up a kilobit, and 1,000,000 bits make a megabit. Your system may have options like 96 kbps, 128 kbps, 2.5 mbps or similar. That’s how many bits can be processed at any time.
Bitrate is the reason two cameras with the same resolution capture completely different footage.
You might have seen examples of pixelated or low-resolution CCTV footage. This is because the bitrate is not high enough to process the image properly, resulting in poor-quality video.
What affects bitrate?
Resolution
Higher resolution cameras are capturing and processing more information.
That means they require a higher bitrate to show a good quality image.
So, even though your surveillance cameras are technically recording in 1080p you will get a drastically different output depending on the bitrate.
Frame Rate
The same logic applies to frame rates which is why you won’t see a lot of 60fps home CCTV in Perth.
More frames means more data, which requires more processing power.
Compression
All video is compressed: compression reduces huge images to a manageable file size, making it easier to send data over a network.
Many CCTV camera systems use H.264 compression which splits the image into a series of small grids and updates parts of the image as something changes.
Castle Security supply and install CCTV camera systems that use H.264+ compression, saving up to 50% bandwidth and storage allocation to give higher quality surveillance video over the same network.
Why the bitrate matters?
Cameras turn what they see into data that whizzes through the network, to be output as video. The more data that can be processed at any time with a higher bitrate, the better video quality you will see.
The right amount of processing power can be the difference between capturing details an intruder’s face or being left with an unusable blurry image.
Setting the right bitrate
We can help you adjust your home or business CCTV camera settings during setup based on the bandwidth available to ensure a crisp image.
The table below shows the required bitrate using H.264+ compression, up to the maximum bitrate for recording complex scenes.
The right amount of processing power can be the difference between capturing details an intruder’s face or being left with an unusable blurry image.
| Image resolution | Frames per second | Average bitrate |
Maximum bitrate
|
| 720p (1280 x 720) | 30 | 1.8 mbps | 2.5 mbps |
| 720p (1280 x 720) | 25 | 1.4 mbps | 2 mbps |
| 1080p (1920 x 1080) | 30 | 2.5 mbps | 5 mbps |
| 1080p (1920 x 1080) | 25 | 2 mbps | 4 mbps |
| 4MP (2560 x 1920) | 30 | 3.8 mbps | 8 mbps |
| 4MP (2560 x 1920) | 25 | 3.2 mbps | 6.7 mbps |
Setting a bitrate below these values will result in low quality video from your CCTV cameras. Of course, you need the available bandwidth on your network to ensure you can send the data from camera to recorder: if your existing network is struggling you can reduce the image resolution or FPS to reduce the bitrate, lightening the bandwidth load.
Not sure what bitrate you need? We can help.
As you can see, setting the right CCTV camera bitrate can start to get pretty technical.
With Castle Security setting up your surveillance cameras at home or the office you don’t need to worry: we’ll take care of the technical side and explain it all to you in plain English.