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MPEG-2 Configuration
VBrick MPEG-2 Appliance Admin Guide 7
original content and signal, and the quality of the decoder and monitor. As a general rule, use
the lowest video rate that best suits the application.
The following information represents guidelines for product configuration limitations, with
regard to specific unit types. When configuring VBrick units, close attention must be paid to
the total transport rate of all sources both entering and exiting the unit. In most cases the
sum of all entering and exiting MPEG-2 data traffic should be closely monitored and kept to
a minimum whenever possible. Once a configuration is decided upon and applied to the unit,
the user can check the status of processor and device load via the IWS or CLI. The CPU
utilization and overloaded status variables are an excellent indication on the overall unit's
health. If the CPU utilization is high or the overloaded condition is occurring, the user may
simply reduce video transport rates and re-run the test. As a part of regular maintenance,
users should periodically check the CPU utilization, overloaded and buffer full count status
variables to ensure the unit remains within its operating limits.
MPEG-2 Configuration Recommendations
• Maintain video rates at optimum levels. High rates do improve quality. VBrick
recommends rates that use the lowest possible rate which gives acceptable quality. For
MPEG-2, rates between 5 and 7 MBPS exhibit excellent video quality.
• Avoid setting the transport rate manually. Use the automatic transport rate calculation
mode (default operation).
• The maximum MPEG-2 transport rate of 17 megabits per second should be used
judiciously.
• When using the hard drive, especially for recording, keep other device functions to a
minimum to avoid discontinuities in the recorded content.
• Recording high video rate streams consumes hard drive space and limits the recording
duration significantly. Additionally, high video rate streams require faster hard drive
access times and are more prone to video dropouts.
• Periodic re-formatting of the hard drive will improve overall disk performance by
reducing disk fragmentation, much like a computer behaves.
• Hard drive pump and record functions are designed to be mutually exclusive. When
operating at medium to low rates it may be possible for the hard drive to pump and
record simultaneously but it is not recommended.
• Encoding from and sending to multiple destinations consumes additional system
resources. Furthermore, a 4300 VBrick unit with dual encoders is capable of sending 4
streams but will not be able to sustain operation at the highest transport rates.
• Increasing the IP video packet size improves overall performance both in Ethernet
Mode. Please check with your network administrator first before deciding on what size is
best for your network.
Absolute Maximum Transport Rates
This table provides the absolute maximum transport rates for given configurations.
Table 3. Maximum Transport Rate by Configuration
Model Dest1, Dest2
Slot #1
Decoder
Slot#2
Recorder FTP Active Player /
Pump
6200 17,0 17 0 No 0