Overview

Synthesis filterbank of an oversampled filterbank with selectable prototype filter

Discussion

This module implements version 2 of the synthesis 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 you specify the FFT size K, the prototpe filter length, and the output time domain block size. The oversampling factor of the filterbank equals K / (output block size). You should strive to have an oversampling factor of at least 2.0 for V1. 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

Pins

Input Pins

Name: f

Description: Frequency domain subbands

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Sample rate range: Unrestricted

Complex support: Complex

Output Pins

Name: t

Description: Time domain signal

Data type: float

Scratch Pins

Channel count: 1

Block size: 65

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Block size: 128

Sample rate: 3072000

MATLAB Usage

File Name: wola_synthesis_v2_subsystem.m

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