Quantize and encode floating-point inputs to integer outputs
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Syntax
y = uencode(u,n)
y = uencode(u,n,v)
y = uencode(u,n,v,'SignFlag')
Description
example
y = uencode(u,n) quantizes the entries in a multidimensional array of floating-point numbers u and encodes them as integers using 2n-level quantization. The output y and the input u are arrays of the same size. The elements of the output y are unsigned integers with magnitudes in the range [0, 2n – 1].
y = uencode(u,n,v) allows the input u to have entries with floating-point values in the range [-v,v] before saturating them (the default value for v is 1).
y = uencode(u,n,v,'SignFlag') maps entries in a multidimensional array of floating-point numbers u whose entries have values in the range [-v,v] to an integer output y. Input entries outside this range are saturated.
Examples
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Map Floating-Point Scalars to Integers
Open Live Script
Map floating-point scalars in [-1, 1] to uint8 (unsigned) integers. Produce a staircase plot. The horizontal axis ranges from -1 to 1 and the vertical axis from 0 to 7 (i.e., ).
u = -1:0.01:1;y = uencode(u,3);plot(u,y,'.')
Look at saturation effects when you underspecify the peak value for the input.
u = -2:0.5:2;y = uencode(u,5,1)
y = 1x9 uint8 row vector 0 0 0 8 16 24 31 31 31Specify you want signed output.
u = -2:0.5:2;y = uencode(u,5,2,'signed')y = 1x9 int8 row vector -16 -12 -8 -4 0 4 8 12 15Input Arguments
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u — Floating point input
matrix | vector
Floating point input, specified as a matrix or a vector. The input may be real or complex. Elements of the input u outside of the range [-1,1] are treated as overflows and are saturated:
For entries in the input
uthat are less than -1, the value of the output ofuencodeis 0.For entries in the input
uthat are greater than 1, the value of the output ofuencodeis 2n – 1.
Data Types: single | double
n — Measure of number of quantization levels
positive integer scalar
Measure of number of quantization levels, specified as a positive integer scalar. n must be an integer between 2 and 32 (inclusive).
v — Peak value
1 (default) | positive real scalar
Peak value, specified as a positive real scalar. Elements of u outside of the range [-v,v] are treated as overflows and are saturated:
For input entries less than -
v, the value of the output ofuencodeis 0.For input entries greater than
v, the value of the output ofuencodeis 2n – 1.
'SignFlag' — Sign of output
"unsigned" (default) | "signed"
Sign of output, specified as "unsigned" or "signed". The integer type of the output depends on the number of quantization levels 2n and the value of 'SignFlag', which can be one of these:
"signed"— Outputs are signed integers with magnitudes in the range [–2n/2, (2n/2) – 1]."unsigned"— Outputs are unsigned integers with magnitudes in the range [0, 2n – 1].
Output Arguments
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y — Encoded integer outputs
vector | matrix
Encoded integer outputs, returned as a vector or a matrix.
Algorithms
The uencode function maps the floating-point input value to an integer value determined by the requirement for 2n levels of quantization. This encoding adheres to the definition for uniform encoding specified in ITU-T Recommendation G.701. The input range [-v,v] is divided into 2n evenly spaced intervals. Input entries in the range [-v,v] are first quantized according to this subdivision of the input range, and then mapped to one of 2n integers. The range of the output depends on whether or not you specify that you want signed integers.
The output data types are optimized for the number of bits as shown in the table below.
n | Unsigned Integer | Signed Integer |
|---|---|---|
2 to 8 | uint8 | int8 |
9 to 16 | uint16 | int16 |
17 to 32 | uint32 | int32 |
References
[1] International Telecommunication Union. GeneralAspects of Digital Transmission Systems: Vocabulary of Digital Transmissionand Multiplexing, and Pulse Code Modulation (PCM) Terms.ITU-T Recommendation G.701. March, 1993.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Usage notes and limitations:
Input
nmust be a compile-time constant.Optional arguments must be compile-time constants.
Version History
Introduced before R2006a
expand all
R2022b: Generate C and C++ code
The uencode function supports C/C++ code generation.
See Also
udecode
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