Net-2000™ Voice Codec Unit
User’s Manual
Page 37
Section 3 – Net-2000™ VCU Control
DVSI Confidential Proprietary
Upon receipt of an Encode command packet the Net-2000™ VCU begins encoding the data by
calling the appropriate vocoder software interface function. At the same time the VCU responds with
a Channel response packet (Table 45 Channel Response Packet). The format of the Channel
response packet is discussed in the Channel response section below.
For Encode command packets and Voice response packets this is the format of the voice data in the
packet. For Decode command packets this is the format of the voice data to be synthesized by the
decoder. For Channel response packets this is the format of the voice data used to encode the
channel data.
cmode
parameter bits
Encoder Command
Packet Flags
Byte 18
7 6 5 4 3 2 1 0
Byte 19
7 6 5 4 3 2 1 0
Bits
AMBE DTMF SEND FLAG
If set, the encoder ignores the voice[] array
and encodes a frame of tone data described
by the tone parameter instead (see Tables 9
and 10). If cleared the data in voice[] is
encoded.
0 1 0 0 0 0 0 0
0 0 0 0 0 0 0 0
14
AMBE TONE DET ENABLE FLAG
If set, the encoder analyzes the voice data
with the tone detector enabled. If cleared the
tone detector is disabled.
0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0
12
AMBE DTX ENABLE FLAG
If set, the encoder enables silence frame
generation for DTX. If cleared all voice and
silence frames are transmitted.
0 0 0 0 1 0 0 0
0 0 0 0 0 0 0 0
11
AMBE NS ENABLE FLAG
If set, the encoder enables noise suppression.
If cleared, noise suppression is disabled.
0 0 0 0 0 0 0 0
0 1 0 0 0 0 0 0
6
*Not Used
* x * x x * * *
* x * * * * * *
15, 13, 10,
9, 8, 7, 5, 4,
3, 2, 1, 0
Table 24 cmode Bits for Encoder Command Packets
The AMBE/AMBE+ coder only supports the DTMF_SEND_FLAG. For this coder tone detection is
always enabled, it has no noise suppressor, and DTX is enabled only if VAD is enabled using the
web interface or command line. The mu-law and A-law coders do not support any of these flags.
The ws element of the packet should contain the number of samples that were encoded. The format
element of the packet should contain the format of the voice data that was encoded. See Table 19
tone.idx—Channel-Parameter, Table 20 tone.amp -- Channel-Parameter, Table 21 ws -- Channel
Parameter for more information on the tone.idx, tone.amp, ws, and format parameters for the
Channel response packet. The least significant bit of each byte of the channel[] array in the packet
contains one bit of channel data output by the encoder.