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Vector Quantizer Decoder

Find vector quantizer codeword that corresponds to zero-based index value

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  • Vector Quantizer Decoder block

Libraries:
DSP System Toolbox / Quantizers

Description

The Vector Quantizer Decoder block associates each input index value with a codeword, expressed as 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. The block creates this matrix by horizontally concatenating the codeword vectors that correspond to each index value.

Ports

Input

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Specify the index values to be a scalar or a row vector in the range 0 ≤ index < N, where N is the number of columns of the codebook matrix.

Data Types: int8 | int16 | int32 | uint8 | uint16 | uint32

Specify the codebook values as a vector or a matrix,

Data Types: single | double | int8 | int16 | int32 | fixed point

Output

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Quantized output values, returned as a vector or a matrix.

These quantized output values always have the same data type as the codebook values. When you specify the codebook values via an input port, the block assigns the same data type to the Q(U) output port. When you specify the codebook values via the dialog box, use the Codebook and output data type parameter to specify the data type of the Q(U) output port.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | fixed point

Parameters

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Main Tab

Specify the action to take when an input index value is out of range, where 0 ≤ index < N and N is the length of the codebook vector (or the number of columns in the codebook matrix).

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. Select Clip and warn to be warned when the block sets any index values less than 0 to 0 and any index values greater than or equal to N to N−1. Select Error for the simulation to stop and display an error when the index values are out of range.

Specify the source of the codebook values as one of these options:

  • Specify via dialog –– Specify codebook values in the Codebook values parameter.

  • Input port –– Specify codebook values through the input port C.

Specify the codebook values as a k-by-N matrix of quantized output 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. 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.

Dependencies

To enable this parameter, set the Source of codebook parameter to Specify via dialog.

Data Types Tab

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.

Dependencies

To enable this parameter, 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.

Block Characteristics

Data Types

fixed point | integer

Direct Feedthrough

no

Multidimensional Signals

no

Variable-Size Signals

no

Zero-Crossing Detection

no

References

[1] Gersho, A. and R. Gray. Vector Quantization and Signal Compression. Boston: Kluwer Academic Publishers, 1992.

Extended Capabilities

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.

Version History

Introduced before R2006a

See Also

(Simulink) | | | |