E-30
Setting
●
Ensure that there is sufficient network
bandwidth for the data volume to be sent out
by VN-C215V4U.
●
Data volume to be sent by VN-C215V4U
varies with the settings and number of
distributions.
●
The maximum bit rate from VN-C215V4U is
about 9 Mbps.
Estimation of total bit rate
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
average size of multiple JPEG images is the
target file size.
VN-C215V4U accepts requests from up to a
maximum of 5 clients. In addition, it also allows
transmission of 1 multicast stream. The total
frame rate refers to the sum of these frame rates.
For example, when 10 fps is requested by 2
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
Insufficient network bandwidth
When there is insufficient bandwidth, the
number of JPEG frames (frame rate) that the
client can acquire will decrease.
Network Delay
When the client acquires JPEG via TCP, VN-
C215V4U will send out data while checking the
ACK from the client at the same time. For
networks with considerable delay, data cannot
be sent out until ACK is received, and therefore
the frame rate will drop.
Drop of frame rate due to network delay can be
eliminated by sending data via multicast.
Network Jitter
When there is considerable network jitter, delay
time may be prolonged and the image frame rate
may drop.
Packet Loss
When acquiring images from VN-C215V4U via
TCP, packet loss may be recovered by
resending by TCP. When there is considerable
delay during resending, however, missing data
may occur and the image frame rate may drop.
When packet loss occurs during multicast
sending from VN-C215V4U, the image frame
rate may drop.
List of protocols and port numbers used
by VN-C215V4U
VN-C215V4U uses the protocols and port
numbers listed below. Ensure that these ports
are allowed through the firewall when a firewall
is to be installed.
Network Requirements
Picture Quality
Control Method
VGA File
Size
QVGA
File Size
VFS
(Variable
File Size)
1 (High)
80 KB
27 KB
2
60 KB
20 KB
3
40 KB
13 KB
4 (Medium)
30 KB
10 KB
5
25 KB
8 KB
6
20 KB
7 KB
7 (Low)
15 KB
5 KB
AFS
(Average File Size)
Selection
may be
made from
the range
between 10
and 100 KB
Selection
may be
made from
the range
between 3
and 33 KB
Protocol/Port No.
Purpose of Use
TCP/80
JPEG acquisition,
Web Settings page,
API
TCP/20, 21
FTP
TCP/25
Mail delivery
TCP/User Setting No.
Alarm sending
UDP/User Setting No.
Alarm sending
UDP/User Setting No.
Multicast sending
UDP /123
SNTP
VN-C215_EN.book Page 30 Tuesday, March 20, 2007 1:54 PM
