DDZ40(10)(20)-YY/HS/HD
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Frames/Second
The frame rate (value in fps) defines the number of consecutive frames produced per
second. The higher the frame rate, the smoother the video playback.
However, a higher frame rate also requires a higher bandwidth usage (transmission ca-
pacity) and more hard disk storage space for the recording of video material.
25 (“PAL countries”) or 30 fps (“NTSC countries”) meet the requirements for real-time ap
-
plications.
Bitrate
The bit rate refers to the number of bits per second used to encode the video. The more
bits are used to represent the video data per second, the higher the quality is.
However, a higher bit rate also requires a higher bandwidth usage (transmission capacity)
and more hard disk storage space for the recording of video material.
Low bit rate
High image compression
Small data volume
Poor image quality
Low bandwidth and hard disk space usage
High bit rate
Low image compression
Large data volume
High image quality
High bandwidth and hard disk space usage
Usually, most requirements in surveillance applications are met with a bit rate between 4
and 6 Mbps.
Bitrate mode
The bit rate mode allows you configure a constant (CBR) or a variable bit rate (VBR) for
the video encoding.
The VBR correlates with the changes in the image dynamically.
In scenes with many changes in the image the bit rate is temporarily increased.
The admissible deviations from the defined bit rate are indicated in percentages. The
higher the percentage value, the higher the maximum admissible peak rate and the
longer the regulation time to return to the nominal bit rate.
Example:
In case of a defined (nominal) bit rate of 4 Mbps and a bit rate mode of “variable 100 %”
the peak rate may temporarily increase to up to 8 Mbps.
Variable bit rates allow for a higher image quality while simultaneously enabling a better
use of both available hard disk storage space and transmission capacities.
A constant bit rate on the other hand allows for a more precise calculation of required
storage capacity.
