DDF4220HDV Picodome
®
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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, higher frame rate also requires higher bandwidth (transmission capacity) 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
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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, higher bit rate also requires higher bandwidth (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 small hard disk space
High bit rate
Low image compression
Large data volume
High image quality
High bandwidth and large hard disk space
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 to configure a constant (CBR) or a variable bit rate (VBR)
for video encoding.
The VBR dynamically correlates with the changes in the image.
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.
On the one hand, variable bit rates allow for a higher image quality while simultaneously
enabling a better use of both: the available hard disk storage space and transmission
capacities.
On the other hand, a constant bit rate allows for a more precise calculation of the required
storage capacity.
