MicroStreamer-PoE
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Select the
Bitrate mode
.
Select the
GOP-size
(only with MPEG).
If required, activate the
B-Frames
checkbox (only possible at a GOP-size > 6).
Frames/Second
The frame rate (value in fps) defines the number of consecutive frames produced per se-
cond. The higher the frame rate is, the smoother the video playback.
Note that audio encoding is only available at a frame rate of 25 fps (PAL) or 30 fps (NTSC).
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 surveillance 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.
Variable bit rates make better use of the available hard disk space.
GOP-size
GOP (
G
roup
O
f
P
ictures) is a variable for specifying how images are used to generate the
MPEG data stream.
The higher the GOP-size is, the better the image quality, although a higher GOP-size will
also result in an increase in the delay. A GOP-size between 6 and 15 generally represents
a good compromise enabling good image quality with high compression.
A GOP-size of 1 denotes a low compression factor and should only be used for special
applications (e.g. multiplex mode).
As from a GOP-size of 6 the use of
B-Frames
can be enabled by checking the appropriate
checkbox. This setting also has a positive effect on the image quality but again results in
a slight delay.
GOP-sizes greater than 15 belong to the
extended GOPs
.
