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Net-2000™ Voice Codec Unit
User’s Manual
Page 36
Section 3 – Net-2000™ VCU Control
DVSI Confidential Proprietary
All other formats are invalid.
Encode Command Packet
To run an encoding communications session the Net-2000™ VCU must receive Encode command
packets (Table 23 Encode command packet) from the control PC. Encode command packets need
to contain 8 kHz voice data in either 16-bit linear, 8-bit A-law, or 8-bit µ-law format and the control
flags and data needed to run the encoder.
The cmode element of the packet contains the mode flags that enable various features of the
encoder such as tone detection as shown in Table 24 cmode Bits for Encoder Command Packets. If
the cmode element has the AMBE DTMF SEND FLAG bit set to force the encoder to generate a
tone, the index and amplitude of the tone to generate are in the tone.idx and tone.amp elements of
the packet, respectively. Values for tone.idx are shown in Table 19 tone.idx. The valid range for
tone.amp is shown in Table 20 tone.amp -- Channel-Parameter.
The ws element of the packet contains the number of voice samples in the packet. The format
element of the packet indicates the format of the voice data. Values for these parameters are also
shown inTable 21 ws -- Channel Parameter. The voice[] data in the packet must be 16-bits per
sample. A-law and µ-law data are passed in the lower eight bits of each sample.
Encode Command Packet
Bytes
(msb-lsb)
Bit
7 6 5 4 3 2 1 0
Bit
7 6 5 4 3 2 1 0
Parameter Name
0 - 1
0 0 0 0 0 0 x x
x x x x x x x x
len
2 - 3
0 0 0 0 0 0 0 0
0 0 0 0 0 0 1 0
type
Header
4 - 5
x x x x x x x x
x x x x x x x x
seq
6 - 7
0 0 0 0 0 0 0 0
1 1 0 0 0 x x x
rate [0]
8 - 9
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
rate [1]
10 - 11
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
rate [2]
12 - 13
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
rate [3]
14 - 15
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
rate [4]
16 - 17
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
rate [5]
18 - 19
0 x 0 0 0 0 0 0
0 0 0 0 0 0 0 0
cmode
20 - 21
0 0 0 0 0 0 0 0
1 0 x x x x x x
tone.idx
22 - 23
x 0 0 0 0 0 0 0
0 x x x x x x x
tone.amp
24 - 25
0 0 0 0 0 0 0 0
1 0 x x x x x x
ws
26 - 27
0 0 0 0 x x x x
0 0 0 x 0 0 x x
format
28 - 29
x x x x x x x x
x x x x x x x x
voice [0]
30 - 31
x x x x x x x x
x x x x x x x x
voice [1]
…
x x x x x x x x
x x x x x x x x
voice [2]
(len-2) - (len-1)
x x x x x x x x
x x x x x x x x
voice [ws-1]
Table 23 Encode command packet