Net-2000™ Voice Codec Unit
User’s Manual
Page 44
Section 3 – Net-2000™ VCU Control
DVSI Confidential Proprietary
Voice Packet Bytes 26 & 27 (format)
The format element of the voice packet also indicates the format of the voice data in the
voice[]
array. Appropriate values voice data type in the format element is listed in Table 11.
format
= Soft decision &
voice data
Voice Data Formats
Byte 26
7 6 5 4 3 2 1 0
Byte 27
7 6 5 4 3 2 1 0
Hex Value
Linear 16-bit PCM
0 0 0 0 x x x x
0 0 0 0 0 0 0 0
0xXX00
A-Law
0 0 0 0 x x x x
0 0 1 0 0 0 0 1
0xXX21
u-Law
0 0 0 0 x x x x
0 0 0 1 0 0 0 1
0xXX11
Table 34 format Parameters
The voice data format to synthesize is as follows:
The voice data to be synthesized is 16 bit PCM
(format & 0x00ff) == 0x00
Voice Packet Bytes 28-347 (voice [ ])
The number of elements in the voice[] array can vary between 159 and 161. The nominal number of
elements should be 160. The voice format is 16 bit PCM each element of the voice array should
contain one linear 16 bit voice sample.
Reset Packet
The Reset packet is used to reset the encoder and decoder state when the VCU is in File Mode. In
order to get reproducible, bit-exact results in File Mode the state of the vocoder must be reset before
sending Channel or Voice packets to the VCU.
Reset 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
0 0 0 0 1 0 0 0
len
2 – 3
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 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
0 0 0 0 0 0 x x
which
Table 35 Reset Packet
Reset packets have the following format described Table 18 and C-language data structure below:
struct reset_packet_t {
short len;
short type;
short seq;
short which;
};
The size of the Reset packet is eight bytes. The elements of the Reset packet are described in detail
in the following sections.