Scalar Quantizer Decoder
Convert each index value into quantized output value
Library
Quantizers
dspquant2
Description
The Scalar Quantizer Decoder block transforms the zero-based input index values into quantized output values. The set of all possible quantized output values is defined by the Codebook values parameter.
Use the Codebook values parameter to specify a matrix containing
all possible quantized output values. You can select how you want to enter the codebook
values using the Source of codebook parameter. When you select
Specify via dialog
, type the codebook values into the
block parameters dialog box. When you select Input port
, port
C appears on the block. The block uses the input to port C as the Codebook
values parameter.
The input to this block is a vector of integer index values, where 0 ≤ index <N and N is the number of distinct codeword vectors in
the codebook matrix. Use the Action for out of range index value
parameter to determine what happens when an input index value is outside this range.
When you want any index value less than 0 to be set to 0 and any index value greater
than or equal to N to be set to N -1, select
Clip
. When you want to be warned when clipping occurs,
select Clip and warn
. When you want the simulation to stop
and the block to display an error when the index values are out of range, select
Error
.
Data Type Support
The data type of the index values input at port I can be
uint8
, uint16
,
uint32
, int8
,
int16
, or int32
. The data
type of the codebook values input at port C can be
double
, single
, or
Fixed-point.
The output of the block is the quantized output values. If, for the
Source of codebook parameter, you select
Specify via dialog
, the Codebook and output
data type parameter appears. You can use this parameter to specify
the data type of the codebook and quantized output values. In this case, the data
type of the output values can be Same as input
,
double
, single
,
Fixed-point
, or
User-defined
. If, for the Source of
codebook parameter you select Input port
,
the quantized output values have the same data type as the codebook values input at
port C.
Dialog Box
The Main pane of the Scalar Quantizer Decoder block dialog appears as follows.
- Action for out of range index value
Use this parameter to determine the block's behavior 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 N -1. SelectClip and warn
, when you want to be warned when clipping occurs. SelectError
, when you want the simulation to stop and the block to display an error when the index values are outside the range.- Source of codebook
Choose
Specify via dialog
to type the codebook values into the block parameters dialog box. SelectInput port
to specify the codebook using input port C.- Codebook values
Enter a vector of quantized output values that correspond to each index value. Tunable (Simulink).
The Data Types pane of the Scalar Quantizer Decoder block dialog appears as follows.
- Codebook and output data type
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 Data Types of Signals (Simulink) 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 toInput port
, the output values have the same data type as the input codebook values.
Codebook and Output Data Type Assistant Parameters
Select how you would like to specify the data type properties of the Codebook and output data type. You can choose:
Inherit
— Lets you specify a rule for inheriting a data type, for example,Inherit: Same as input
Built in
— Lets you specify a built in data type, for example,double
Fixed point
— Lets you specify the fixed-point attributes of the data type.Expression
— Lets you specify an expression that evaluates to a valid data type, for example,fixdt(1,16)
Specify the Signedness for the Codebook and output data type.
Specify the Scaling for the Codebook and output data type.
For more information see Scaling in the DSP System Toolbox™ User's Guide.
Specify the Word length for the Codebook and output data type.
Specify the Fraction length for the Codebook and output data type.
Specify the data type override mode. You can select one of the following options:
Inherit
— Inherits the data type override setting specified for the model.Off
— Ignores the data type override setting specified for the model and uses the fixed-point data type you specify
This parameter appears only when you set the Mode parameter
to Built in
or Fixed Point
.
For more information, see Specify Data Types Using Data Type Assistant (Simulink).
References
Gersho, A. and R. Gray. Vector Quantization and Signal Compression. Boston: Kluwer Academic Publishers, 1992.
Supported Data Types
Port | Supported Data Types |
---|---|
I |
|
C |
|
Q(U) |
|
For more information on what data types are supported for each quantizer mode, see Data Type Support.
See Also
Quantizer (Simulink) | Simulink |
Scalar Quantizer Encoder | DSP System Toolbox |
Uniform Encoder | DSP System Toolbox |
Uniform Decoder | DSP System Toolbox |
Extended Capabilities
Version History
Introduced before R2006a