VIVOTEK
58 - User's Manual
The frame rate will decrease if you select a higher resolution.
■ Intra frame period
Determine how often to plant an I frame. The shorter the duration, the more likely you will get
better video quality, but at the cost of higher network bandwidth consumption. Select the intra
frame period from the following durations: 1/4 second, 1/2 second, 1 second, 2 seconds, 3
seconds, and 4 seconds.
■
Video quality
Constant bit rate:
•
Constant bit rate
: A complex scene generally produces a larger file size, meaning that
higher bandwidth will be needed for data transmission. The bandwidth utilization is
configurable to match a selected level, resulting in mutable video quality performance.
The bit rates are selectable at the following rates:
20Kbps, 30Kbps, 40Kbps, 50Kbps,
64Kbps, 128Kbps, 256Kbps, 512Kbps, 768Kbps, 1Mbps, 2Mbps, 3Mbps, 4Mbps, 6Mbps,
8Mbps, 10Mbps, 12Mbps, 14Mbps, 16Mbps, 18Mbps, and 20Mbps
. You can
also select
Customize
and manually enter a value.
- Target bit rate
: select a bit rate from the pull-down menu. The bit rate ranges
from 20kbps to a maximum of 20Mbps. The bit rate then can be a limiting factor for
controlling the quality and the bandwidth consumed for transmitting this video stream.
This bit rate restriction method is particularly useful when planning a configuration
consisting of numerous cameras where video streams can produce high demands
both on network bandwidth and storage space.
For example, storing a
6Mbps stream
for 24 hours requires a 63GB disk space. The Network Camera will strive to deliver
video streams
within the bit rate limitation you impose.
- Policy:
If Frame Rate Priority is selected, the Network Camera will try to maintain
the frame rate per second performance, while image quality will be compromised. If
Image quality priority is selected, the Network Camera may drop some video frames
in order to maintain image quality.
• Fixed quality:
On the other hand, if
Fixed quality
is selected, all frames are
transmitted with the
same quality; bandwidth utilization is therefore unpredictable. If
Fixed quality is selected, frame rate performance will be compromised.
- Quality:
You can select the following quality options - Medium, Standard,
Good, Detailed, and Excellent. The image quality will then be determined by the
compression rate. For example, a lower quality means a higher compression rate.
The higher the compression rate, the higher the possibility of image distortion, etc.
You can also select
Customize
and manually enter a logical value from 0 to 51.
- Maximum bit rate:
With the guaranteed image quality, you might still want to place
a bit rate limitation to control the size of video streams for bandwidth and storage
concerns. The configurable bit rate starts from 1Mbps to 40Mbps.
You may also manually enter a bit rate number by selecting the
Customized
option.
If
JPEG
mode is selected, the Network Camera continuously sends JPEG images to the client,
producing a moving effect similar to a filmstrip. Every single JPEG image transmitted guarantees
the same image quality, which in turn comes at the expense of variable bandwidth usage. Because
the media contents are a combination of JPEG images, no audio data is transmitted to the client.
There are three parameters provided in MJPEG mode to control the video performance:
