Find vector quantizer codeword that corresponds to given, zerobased index value
Quantizers
dspquant2
The Vector Quantizer Decoder block associates each input index value with a codeword, a column vector of quantized output values defined in the Codebook values parameter. When you input multiple index values into this block, the block outputs a matrix of quantized output vectors. This matrix is created by horizontally concatenating the codeword vectors that correspond to each index value.
You can select how you want to enter the codebook values using
the Source of codebook parameter. When you select Specify
via dialog
, you can type the codebook values into the
block parameters dialog box. Select Input port
and
port C appears on the block. The block uses the input to port C as
the Codebook values parameter.
The Codebook values parameter is a kbyN matrix of values, where k ≥ 1 and N ≥ 1. Each column of this matrix is a codeword vector, and each codeword vector corresponds to an index value. The index values are zero based; therefore, the first codeword vector corresponds to an index value of 0, the second codeword vector corresponds to an index value of 1, and so on.
The input to this block is a vector of index values, where 0
≤ index < N and N is
the number of columns of the codebook matrix. Use the Action
for out of range index value parameter to determine how
the block behaves when an input index value is out of this range.
When you want any index values less than 0 to be set to 0 and any
index values greater than or equal to N to be set
to N1, select Clip
.
When you want to be warned when any index values less than 0 are set
to 0 and any index values greater than or equal to N are
set to N1, select Clip and warn
.
When you want the simulation to stop and display an error when the
index values are out of range, select Error
.
The input to the block can be the index values and the codebook
values. The data type of the index input to the block at port I can
be uint8
, uint16
, uint32
, int8
, int16
,
or int32
. The data type of the codebook
values can be double
, single
,
or Fixedpoint.
The output of the block is the quantized output values. These
quantized output values always have the same data type as the codebook
values. When the codebook values are specified via an input port,
the block assigns the same data type to the Q(U) output port. When
the codebook values are specified via the dialog, use the Codebook
and output data type parameter to specify the data type
of the Q(U) output port. The data type of the codebook and quantized
output can be Same as input
, double
, single
, Fixedpoint
, Userdefined
,
or Inherit via back propagation
.
The Main pane of the Vector Quantizer Decoder block dialog appears as follows.
Choose the behavior of the block when an input index value is
out of range, where 0 ≤ index < N and N is
the length of the codebook vector. Select Clip
when
you want any index values less than 0 to be set to 0 and any index
values greater than or equal to N to be set to N1.
Select Clip and warn
when you want to be
warned when any index values less than 0 are set to 0 and any index
values greater than or equal to N are set to N1.
Select Error
when you want the simulation
to stop and display an error when the index values are out of range.
Choose Specify via dialog
to type
the codebook values into the block parameters dialog box. Select Input
port
to specify the codebook values using the block's
input port, C.
Enter a kbyN matrix
of quantized output values, where 1 ≤ k and 1
≤ N . Each column of
your matrix corresponds to an index value. This parameter is visible
if, from the Source of codebook list, you
select Specify via dialog
.
The Data Types pane of the Vector Quantizer Decoder block dialog appears as follows.
Specify the data type of the codebook and quantized output values. You can select one of the following:
A rule that inherits a data type, for example, Inherit:
Same as input
.
A built in data type, such as double
An expression that evaluates to a valid data type,
for example, fixdt(1,16)
Click the Show data type assistant button to display the Data Type Assistant, which helps you set the Output data type parameter.
See Control Signal Data Types for more information.
This parameter is available only when you set the Source
of codebook parameter to Specify via dialog
.
If you set the Source of codebook parameter to Input
port
, the output values have the same data type as the
input codebook values.
Gersho, A. and R. Gray. Vector Quantization and Signal Compression. Boston: Kluwer Academic Publishers, 1992.
Port  Supported Data Types 

I 

C 

Q(U) 

Quantizer  Simulink 
Scalar Quantizer Decoder  DSP System Toolbox 
Scalar Quantizer Design  DSP System Toolbox 
Uniform Encoder  DSP System Toolbox 
Uniform Decoder  DSP System Toolbox 
Vector Quantizer Encoder  DSP System Toolbox 