Milestone Central 3.7 - Manual (Page 28)

Milestone XProtect Central 3.7; User’s Manual
• Talk: Button is only available if the camera in question has speakers assigned to it. Press
the button to talk, and keep the button depressed whenever you need to talk. By actively
pressing the button on order to talk, you can avoid irrelevant internal conversations being
transmitted through the speakers. While you speak, a level meter to the right of the button
will indicate the level of your voice. A low deflection on the level meter may indicate that
you need to move closer to your microphone in order for your voice to be audible by your
audience.
Image Quality and Frame Rate
You can change image quality and/or frame rate on the fly while playing back recorded video as
well as while viewing live video. Simply select required image quality and/or
frame rate from the selection boxes in the lower left part of the window.
If you change image quality or frame rate, the video viewed will briefly stop, adjust to the selected
setting, and the start again. This takes less than a second.
• Image quality (left selection box): Determines the quality of video viewed, but also
affects bandwidth usage. If the Central Client is used over the internet, over a slow
network connection, or if for other reasons you need to limit bandwidth use, image quality
can be reduced on the server side by selecting e.g. Low or Medium. When selecting a
reduced image quality, images from the selected camera is re-encoded to a JPEG format on
the surveillance system server before being sent to the Central Client. Re-encoding takes
place along the following lines:
o
Full: The default setting, providing the full quality of the original video.
o
SuperHigh: Re-encoding to an output width of 640 pixels (VGA) and a JPEG quality
level of 25%.
o
High: Re-encoding to an output width of 320 pixels (QVGA) and a JPEG quality
level of 25%.
o
Medium: Re-encoding to an output width of 200 pixels and a JPEG quality level of
25%.
o
Low: Re-encoding to an output width of 160 pixels and a JPEG quality level of 20%.
Height will scale according to the width and the aspect ratio of the original video.
While using a reduced image quality helps limit bandwidth use, it will—due to the need for
re-encoding images—use additional resources on the surveillance system server.
• Viewing frame rate (right selection box): Lets you select a frame rate for the video
viewed. Select between Unlimited, Middle, or Low. The effect of your selection can be
illustrated as follows:
Effect Unlimited Middle Low
JPEG Send all frames Send every 4th
frame
Send every 20th
frame
MPEG (I-frame) Send all frames Send all frames Send all frames
MPEG (P-frame) Send all frames Do not send any
frames
Do not send any
frames
Example: If you set the frame rate option to Low, and the surveillance system
administrator has configured the camera in question to feed JPEG images at a frame rate of
20 frames per second, you will experience an average of 1 frame per second when viewing
video from that camera. If the administrator had configured the camera with a feed as low
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