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CODER MODE
In MPEG modes, the encoder may be set to one of four audio modes. In Mono mode, the entire bit pool is
allocated to one channel. In Dual Mono mode, the bit pool is statically divided into two parts; this implies
that the audio characteristics of one channel do not affect the bandwidth used by the other. In Stereo
mode, correlation is assumed between both channels. The bit pool is dynamically divided into two sliding
parts. This implies that if one channel can be encoded by a small quantity of bits, these may temporarily
be used by the other channel. Finally in Joint Stereo mode, correlation between the input channels is
actively investigated in all sub-bands. In the case of a substantial correlation, a single audio signal and a
"balance" signal are coded instead of two separate audio signals. As this takes fewer bits, more can be
used for the audio signal. The extent to which this is used depends upon the MPEG psycho-acoustic
model.
The PCM input processing technique is set automatically irrespective of the encoder used. This allows the
input PCM data to be averaged in mono mode to be used by both channels.
The parameters and options are shown in the following table:
Field
SLOT
DESTINATION
ACTIVATION TIME
ACTIVATION LEVEL
MODE
SAMPLE CLOCK REF
PCM SAMPLE RATE
FRAME LENGTH
(SAMPLES)
CODER TYPE
CODER BIT RATE
CODER MODE
MPEG TYPE
MPEG LAYER
V100 Versatile Multiplexer Technical Manual Version 2.2
Options
1,2
"NODE:SLOT:CHANNEL",
0,
1-120 seconds
1-10
Analogue,
Digital
GRXCLK,
GTXCLK
48K
384,
512,
1184
None,
G.711,
G.722,
MPEG
8-448K
Various
MPEG-1,
MPEG-2
I,
II
Page 74 of 231
C H A P T E R
3
C O N F I G U R I N G
Description
Selects which card to configure
Remote card address. Channel number is
always 1.
Permanent bandwidth
Connection hold-up time after input signal
mutes
Activation signal threshold
Analogue signal input and output
AES/EBU digital stereo signals using LEFT I/O
connectors
Select reference source for PLL
Information Only
Number of sample per frame for
G.711/G.722
No coder selected
G.711 encoder or decoder selected
G.722 encoder or decoder selected
MPEG encoder or decoder selected
Depends on Coder Mode: See table below
Depends on Coder Type: See table below
Coding standard
MPEG coding complexity
V 1 0 0
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