User`s manual

VPort 2140 User’s Manual Troubleshouting
7-4
Q: How many users are allowed to watch Video Server at the same time?
A: To achieve the best effect, Video Server will allow a maximum of twenty users to connect at the
same time. Excess users can get an auto-refreshed still image on homepage instead. It is
recommended to build another web server to host a large quantity of users by retrieving images
from Video Server periodically.
Q: How fast is the video rate of Video Server?
A: The JPEG codec can process 30 frames per second internally. However, the overall
performance is subject to many different factors, such as:
1. network throughput,
2. bandwidth share,
3. number of users,
4. number of video inputs accessed at one time,
5. viewing complicated objects results in a larger image file,
6. the level of your PC or notebook that is responsible for displaying images.
In general, the transfer rate on a general local network environment can achieve over 200
Kbytes per second and approximately 10 to 20 pictures of normal environment per second. The
general frame size is illustrated in the following table for your reference.
Quality setting Size of each frame Bandwidth demand for 30 fps
Medium 9.3 Kbyte 2246 Kbps
Standard 11.15 Kbyte 2676 Kbps
Good 13.76 Kbyte 3303 Kbps
Detailed 16.35 Kbyte 3925 Kbps
Excellent 20.3 Kbyte 4886 Kbps
Q: How can I keep Video Server as private as possible?
A: Video Server is designed for surveillance purposes and has many flexible interfaces. The user
authentication and special confirmation during installation can keep Video Server from
unauthorized access. You may also change the HTTP port to a non-public number. You can
check system log to examine any abnormal activities and trace the origins.
Q: I have a PTZ camera that is not on the support list. How can I control it?
A: Video Server provides a custom camera command interface to control cameras that are not
supported. The details are described in this manual. Be sure that the COM port settings are
applied to the camera specifications. The camera control cable included is shown in the
package contents. Prepare your own cable if necessary. The general PTZ command is
composed of one start command and one stop command. When editing both commands in the
edit box of the configuration page, use comma(s) to separate commands. Each comma
represents 200 milliseconds. If the user has some serial control device other than the PTZ
camera, the special URL is provided to send the desired commands. For quick access, integrate
the URL to another homepage on your own web server.
Q: Why can I see image files when I use dir in FTP even if the alarm is not triggered?
A: Every time Video Server starts, it will capture the images as vpre.jpg. If there are previously
saved image files that are not retrieved, Video Server will keep them until they are accessed.