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Net-2000™ Voice Codec Unit
User’s Manual
Page 39
Section 3 – Net-2000™ VCU Control
DVSI Confidential Proprietary
cmode parameter bits
Decoder 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 decoder ignores the channel[] array
and synthesizes a frame of tone data
described by the tone parameter instead (see
Tables 9 and 10). If cleared the data in
channel[] is synthesized.
0 1 0 0 0 0 0 0
0 0 0 0 0 0 0 0
14
AMBE CNI FRAME FLAG
If set, the decoder ignores the data in the
channel[] array and inserts a comfort noise
frame. If cleared the decoder synthesizes the
data in channel[].
0 0 0 0 0 0 0 0
0 0 0 0 1 0 0 0
3
AMBE LOST FRAME FLAG
If set, the decoder ignores the data in the
channel[] array and repeats the last valid
frame of data. If cleared the decoder
synthesizes the data in channel[].
0 0 0 0 0 0 0 0
0 0 0 0 0 1 0 0
2
*Not Used
* x * * * * * *
* * * * x x * *
15, 13, 12, 11,
10, 9, 8, 7, 6, 5,
4, 1, 0
Table 26 cmode Bits for Decoder Command Packets
Upon receipt of an Decode command packet terminals should decode the data appropriately by
calling the vocoder software interface function ambe voice dec() twice to produce ws samples of
voice data. The data elements in the packet with the same names as the arguments to ambe voice
dec() (i.e., cmode, etc.) should be passed directly to the decoder function on both invocations. If the
DTMF SEND FLAG is set in the cmode element of the packet, the vocoder software interface function
ambe tone gen() should be called with the tone.idx and tone.amp elements of the packet passed as
arguments before calling the decoder function to force the decoder to generate a tone.
Note: The AMBE/AMBE+ and AMBE+2 coders support all of the decoder cmode input flags,
however the mu-law and A-law coders do not support any of them.
The Net-2000™ VCU responds to an Decoder command packet with a Voice response packet (Table
47 Voice Response Packet). The Voice response packet contains the voice data output by ambe
voice dec(). The format of the Voice response packet is discussed in the Voice response section
below.