It’s a common misconception that the better the quality of an image, the higher the bitrate will be. However, this is not always the case. In fact, sometimes technology developed to improve the usability of a video has the positive side-effect of reducing bitrate since it removes image noise or unwanted movements in the video.
Bitrate in video surveillance is important as it affects the bandwidth capacity and storage of the video. In simple terms, an increase in bitrate increases the bandwidth and storage required.
Important forensic information
Each installation has limitations, challenges and absolute needs. That's why the benefits of keeping a low bitrate varies from case to case. For some, it could be crucial to minimise the investment of storage or bandwidth. For others, the lower bitrate might provide the opportunity to keep the desired frame rate, resolution or retention time.
For some, it could be crucial to minimise the investment of storage or bandwidth
It could even make it possible to add more cameras without the need for increased bandwidth or storage. Keeping the bitrate at an optimum level can be directly related to either increasing image usability or saving money – sometimes both. Axis Lightfinder technology, for example, discerns colour at extreme low-light and produces full-colour videos with important forensic information. Filming in low light often means high levels of image noise but since Lightfinder is developed to keep the image noise to a minimum, it improves both the image quality and keeps down the bitrate.
Bitrate-reducing technologies
Electronic Image Stabilisation (EIS) is another example of making an image more fit for purpose while reducing the bitrate. Cameras mounted on high poles, near busy roads or at industrial sites can be shaken by winds or vibrations. The images are often blurry and troublesome to view. EIS technology detects vibration and shaking in the camera’s movements and automatically adjusts to provide a smooth, stable image that is less ’busy’ (and therefore using less bitrate), so it is easier to see what is happening in the scene.
While these technologies, designed to improve the clarity of an image, have the added bonus of also reducing bitrate, Axis Zipstream has bitrate reduction as its primary objective. Designed specifically to compress videos without losing the quality and detail, Zipstream can dramatically reduce bitrate – by an average of 50% or more. This is of cause the great hero when it comes to bitrate-reducing technologies.
