Net-2000™ Voice Codec Unit
User’s Manual
Page 41
Section 3 – Net-2000™ VCU Control
DVSI Confidential Proprietary
Voice Packet
Voice packets contain the voice data for one frame of voice with the control flags and data needed to
run the encoder. They are also transmitted by the VCU in response to Channel packets when in File
Mode and contain the synthesized speech output by the decoder.
Voice 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 0 0
1 1 0 1 1 0 1 0
len
2 – 3
0 0 0 0 0 0 0 0
0 0 0 0 0 0 1 1
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 0 1 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]
32 – 33
x x x x x x x x
x x x x x x x x
voice [2]
… … … …
344 – 345
x x x x x x x x
x x x x x x x x
voice[159]
Table 28 Encode Packet
Voice packets have the following format described Table 18 and C-language data structure below:
struct voice_packet_t {
short len;
short type;
short seq;
short rate[5];
short cmode;
short tone[2];
short ws;
short format;
short voice[160];
};
The size of the Voice packet can vary depending on the number of samples in the
voice[]
buffer.
The actual number of elements in the
voice[]
buffer can vary between 159 and 161. The nominal
number of samples is 160. The
ws
and
len
elements of the Voice packet should be adjusted to
indicate the actual number of samples in
voice[]
. The elements of the Voice packet are described
in detail in the following sections.