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With MPEG-4 and H.264, users can allow an encoded video stream to have a variable or a constant bit rate.
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Capturing Images
Light levels and reflectances in typical environments.
Resolution
Resolution is similar in the analogue or digital worlds, but there are important differences in how it is defined.
Image Sensors
CCD (Charged Coupled Device) and CMOS (Complementary metal oxide semiconductor).
Scan Technology
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Choosing the Right Lens
The range of lighting from bright sunlight to clear starlight is 109:1 (100,000,000):1.
Comparing Standards
When comparing the performance of MPEG standards such as MPEG-4 and H.264, it is important to note that results may vary between encoders that use the same standard.
Compression Standards
The two basic standards for image compression are JPEG and MPEG.
Wireless Standards
There are two major categories for wireless communications:wireless LANs and wireless bridges.
Quality of Service
Fundamentally different networks are merging into one IP network and shared network resources must be controlled.
You are Here:- Home >> Products >> Network Cameras >> Variable and constant bit rates
Variable and constant bit rates
With MPEG-4 and H.264, users can allow an encoded video stream to have a variable or a constant bit rate. The optimal selection depends on the application and network infrastructure.

Variable bit rate
With VBR (variable bit rate), a predefined level of image quality can be maintained regardless of motion or the lack of it in a scene. This means that bandwidth use will increase when there is a lot of activity in a scene and will decrease when there is no motion. This is often desirable in video surveillance applications where there is a need for high quality, particularly if there is motion in a scene. Since the bit rate may vary, even when an average target bit rate is defined, the network infrastructure (available bandwidth) must be able to accommodate high throughputs.

Constant bit rate
With limited bandwidth available, the recommended mode is normally CBR (constant bit rate) as this mode generates a constant bit rate that can be predefined by a user. The disadvantage with CBR is that when there is, for instance, increased activity in a scene that results in a bit rate that is higher than the target rate, the restriction to keep the bit rate constant leads to a lower image quality and frame rate. Axis network video products allow the user to prioritize either the image quality or the frame rate if the bit rate rises above the target bit rate.
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