User guide

Operating the Multiplexer using nCompass Control
The system responds to variations in the criticality of the source pictures so that the
MX8400 is able to maintain overall picture quality targets by readjusting bit rate
allocations.
4.5.4.3 Features of the Reflex Software
The major features of the Reflex software are:
• Seamless bit rate change from 700 kbps
2
to 10 Mbps in a single frame, two
fields, period (40 ms for PAL-I and 33 ms for NTSC-M).
• Each Encoder can be given a weighting factor.
• Once configured, the Reflex system requires no further Operator involvement.
• Relies on the statistical distribution of bit rate demand across programme
sources.
• Exploits the likelihood that peaks in demand are infrequent on any single
channel.
4.5.5 Using Statistical Multiplexing
4.5.5.1 Introduction
The following information explains the use of statistical multiplexing. The parameters
are entered via nCompass Control for use by the MX8400 Multiplexer.
4.5.5.2 Allocation of Bit rates
A Reflex group (set of Encoders) is allocated a total bit rate which creates a pool
from which the Encoders can draw. The following points should be noted in setting
up a group:
• The number of Encoders in the group.
• The resolution each group is set to.
• The types of material being encoded by each Encoder.
• The noise levels present in the source material.
• The required picture quality.
Table 4.5 can be used as a guideline.
2
The figures shown can vary depending on encoding type and delay mode.
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