FilterbankFIRV2

Overview

Efficient filterbank based FIR filter

Discussion

DSP Concepts Proprietary IP.

This module implements a long FIR filter using filterbank processing. This yields a significant reduction in the processing load and allows much longer filters to be implemented. The filterbank reduces computation by breaking a large convolution into multiple smaller independent convolutions. The implementation supports mono audio channels and an arbitrary block size.

When you instantiate the module you specify the blockSize and the length of the filter L. The larger the blockSize the more efficient the processing. The latency through the filter is zero and is numerically equivalent to having a time domain FIR filter.

On the Inspector (or Numeric Inspector) you specify the time domain FIR filter coefficients. The module will automatically take care of converting the time domain coefficients into the appropriate frequency domain coefficients. For ease of use, it is better to use the Numeric Inspector and then load the coefficients from a text file.

Module Pack

Advanced

ClassID

classID =

Type Definition

typedef struct _ModuleFilterbankFIRV2
{
ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
} ModuleFilterbankFIRV2Class;

Variables

Properties

Name	Type	Usage	Default Value	Range
L	int	const	1024	Unrestricted
FFTSize	int	const	256	Unrestricted
numBlocks	int	const	4	Unrestricted
coeffs	float*	parameter	[1024 x 1]	Unrestricted

Pins

Input Pins


Name	in
Description	Time domain input
Data type	float
Channel range	1
Block size range	256
Sample rate range	Unrestricted
Complex support	Real

Output Pins


Name	out
Description	Time domain output
Data Type	float

Scratch Pins


Channel Count	1
Block size	256
Sample rate	48000


Channel Count	1
Block size	256
Sample rate	48000


Channel Count	1
Block size	257
Sample rate	48000


Channel Count	1
Block size	256
Sample rate	48000


Channel Count	1
Block size	256
Sample rate	48000


Channel Count	1
Block size	256
Sample rate	48000


Channel Count	1
Block size	512
Sample rate	48000

Matlab Usage

File Name: filterbank_fir_v2_subsystem.m 
 SYS = filterbank_fir_v2_subsystem(NAME, L, BLOCKSIZE) 
 Creates a subsystem which implements a long FIR filter efficiently using 
 a filterbank based algorithm.  Arguments: 
    NAME - name of the subsystem 
    L - length of the time domain FIR filter 
    BLOCKSIZE - time domain block size.  This allocates sizes of internal 
       modules and the prebuild function checks that this matches the 
       actual block size. 

 This v2 version of the module no longer requires that the input 
 block size is a power of 2. 

 The function internally uses a combination of Audio Weaver blocks 
 in order to achieve the desired filtering.  The input and output 
 audio are mono.