Overview

Table driven 2d interpolation module. Currently supports only bilinear interpolation

Discussion

This module performs an interpolated 2-dimensional table lookup using a grid of values evenly spaced from -1 to 1. The module currently supports only bilinear interpolation. The input pins specify the X and Y values at which to perform the interpolation. 4 points in the table are used and bilinear interpolation is applied. The X values interpolate along a row and Y values interpolate along a column.

The range of X and Y are always [-1 +1]. Values outside of this range are clipped to +/- 1.

At instantiation, specify the total number of points (NPOINTS) in each dimension of the table. The amount of memory allocated to the table equals (NPOINTS * NPOINTS).

Type Definition

typedef struct _ModuleTableInterp2d
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 nPoints;                                // Number of points in each dimension of the active interpolation table.
    FLOAT32* table;                               // 2d Interpolation Lookup table
} ModuleTableInterp2dClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
nPoints	int	const	0	5	Unrestricted
table	float*	parameter	0	[5 x 5]	Unrestricted

Pins

Input Pins

Name: inx

Description: index x

Data type: float

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Name: iny

Description: index y

Data type: float

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description: audio output

Data type: float

MATLAB Usage

File Name: table_interp2d_module.m

 M=table_interp2d_module(NAME, NPOINTS)
 This Audio Weaver process performs bilinear interpolation between values
 defined on a lattice with NPTS evenly spaced points from [-1,1] in x and
 y.  For input coordinates between the lattice points, interpolate
 linearly for x and then for y.
 
 Arguments:
    NAME - name of the module.
    NPOINTS - number of points in each dimension. This is set at design
       time and has a minimum value of 2.
 The internal variable .table holds the underlying table of values.
 .table has a size of NPOINTS x NPOINTS.