DF4900HD / DF4500HD
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Noise Filter
This function can improve the image quality by noise reduction and therefore enhance the
compression performance.
Note that this function is not effective with resolutions higher than 720p.
Spatial (2D)
• Compares surrounding pixels within a frame
• Most effective on flat areas
• Less effective on gradients
• Can smooth out noise but may cause loss of detail and may blur edges of objects
Temporal (1D)
• Compares pixels between frames
• Most effective in stationary areas without losing detail
• May blur moving objects
S Temporal (3D)
• Compares pixels both within and between frames
• Most effective noise suppression
• May cause high CPU load and therefore may slow down the encoding speed and lead
to loss of frames
• May blur moving objects
• May cause loss of detail
Frames/Second
The frame rate (value in fps) defines the number of consecutive frames produced per sec-
ond. The higher the frame rate is, the smoother the video playback.
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.
Low bit rate
High image compression
Small data volume
Poor image quality
High bit rate
Low image compression
Large data volume
High image quality
The most requirements in CCTV systems are met with a bit rate between 4 and 6 Mbps.
Bitrate mode
The bit rate mode allows configuring a constant or a variable bit rate for the video encoding.
The “variable” mode changes the bit rate in accordance with the activity (changes) in the
image. The allowed bit rate variations can be limited by the according percentage value.
Example:
With a set bit rate of 4 Mbps and a bit rate mode of “variable 50 %”, the bit rate can vary
from 6 to 2 Mbps.
