Network Requirements - JVC VN-V25U Instructions Manual

Network Requirements

● Ensure that there is sufficient network
bandwidth for the data volume to be sent out
by VN-V25U. Do not send multicast stream
that exceeds the bandwidth. If the entire
bandwidth is used by the multicast stream,
control of this camera via the network may fail.
● Data volume to be sent by VN-V25U varies
with the settings and number of distributions.
● The maximum bit rate for transmission is
about 20 Mbps.
Estimation of Total Bit Rate
The total JPEG bit rate from VN-V25U is
determined by the VN-V25U settings, number of
clients, and the client's requested number of
frames. The total MPEG4 bit rate from VN-V25U
is determined by the number of distributions.
Develop a design upon taking the above into
consideration.
Bit Rate of JPEG Stream
The JPEG file size per frame varies with the
encoding settings as well as input video signals.
The following table may be used as a reference.
When VFS is selected, the quantization table
during JPEG encoding will be maintained, and
the file size will increase/decrease according to
the input signals. When AFS is selected,
encoding will be performed such that the target
file size is the average size of multiple JPEG
images.
Picture Quality
Control Method
VFS 1 (High)
(Variable
2
File Size)
3
4 (Medium) 30 KB
5
6
7 (Low)
AFS
(Average File Size)
The maximum number of distributions varies
with the bit rate settings as well as the client's
requested frame rate. Up to 20 streams can be
distributed (including multicast). The total frame
rate refers to the sum of these frame rates.
VGA File QVGA File
Size Size
80 KB 27 KB
60 KB 20 KB
40 KB 13 KB
10 KB
25 KB 8 KB
20 KB 7 KB
15 KB 5 KB
Selectable Selectable
between between
10 KB - 3 KB -
100 KB 33 KB
For example, when 10 fps is requested by two
clients, and in addition, multicast is transmitted
at a rate of 10 fps, the total frame rate will be:
10 + 10 + 10 = 30 fps
If the JPEG file size per frame is 30 KB, then the
total bit rate will be:
30 KB x 30 fps = 900 KB/s = Approx. 7.2 Mbps
Bit Rate of MPEG4 Stream
You can select either the Variable Bit Rate
(VBR) or Constant Bit Rate (CBR) system for
MPEG4 stream.
When the VBR system is selected, the bit rate
varies according to the condition of the input video
signals. The VBR system delivers a stable picture
quality, but forecast of the bit rate is difficult.
When the CBR system is selected, encoding is
performed at a fixed bit rate regardless of the
condition of the input video signals. The picture
quality varies under the CBR system, but the bit
rate can be easily forecast.
You can specify an estimated bit rate for both
VBR and CBR. (64 kbps - 8000 kbps)
Restrictions on the Number of
Distributions for VN-V25U
The maximum number of distributions for
VN-V25U is determined by the settings as well
as requirements from the client.
When only JPEG images are distributed, the
maximum number of distributions is determined
based on the highest bit rate within the stream.
When a distribution request that exceeds the
maximum number of distributions is received,
this request is denied. For example, if Client A
requests for and receives data at 1 Mbps, while
Client B requests for and receives data at
5 Mbps, the maximum number of distributions is
4 streams according to the table below.
Maximum number of distributions when only
JPEG data is distributed
Distribution Maximum
at maximum number of
bit rate distributions
1 Mbps and 20
below
5 Mbps and 4
below
10 Mbps and 2
below
Larger than 1
10 Mbps
Total
maximum bit
rate
20 Mbps
20 Mbps
20 Mbps
Maximum
configurable
value
(24 Mbps)
21