Overview
Analysis filterbank of an oversampled filterbank with selectable prototype filter
Discussion
This module implements version 2 of the analysis portion of a weighted-overlap filterbank. The first parameter is the filter type, v1 is the same prototype filter from the original WOLA. An additional parameter - timeFlip, has been introduced and is only valid for V1. By default the filter will be minimum phase at anaylsis, and maximum phase for synthesis. It may be advantageous to switch this for AEC applications - i.e. use min/max for input and max/min for reference. Note that final signal through analysis / synthesis is always linear phase. For v2, the module argument for attenuation is replaced by filter order. As a module argument, you specify the FFT size K, and the prototype filter order. The module inherits the block size from the input wire. The oversampling factor of the module is defined as K / (input block size). For example, if the block size of the input pin is K/2 then the module has an oversampling factor of 2. For reasonable reconstruction accuracy you should keep the oversampling factor to be at least 2. The module decimates by the input block size and the output sample rate will be reduced accordingly. In general, the V2 version will be equivalent or overperform V1 for lower latencies when the oversampling factor is >= 2, and should be considered for lower latency applications.
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This module is equivalent to V1, except for the method of design of the prototype filters. The Audio Weaver Module Users Guide has extensive documentation for v1 of this module. Please refer to this other document for more general WOLA information.
Type Definition
-Not Shown-
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
latency | int | const | 0 | 352 | Unrestricted | samples |
Pins
Input Pins
Name: t
Description: Time domain signal
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Sample rate range: Unrestricted
Complex support: Real
Output Pins
Name: f
Description: Frequency domain subbands
Data type: float
Scratch Pins
Channel count: 1
Block size: 128
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Block size: 129
Sample rate: 48000
MATLAB Usage
File Name: wola_analysis_v2_subsystem.m
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