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https://github.com/vinniefalco/DSPFilters

A Collection of Useful C++ Classes for Digital Signal Processing
https://github.com/vinniefalco/DSPFilters

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A Collection of Useful C++ Classes for Digital Signal Processing

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## A Collection of Useful C++ Classes for Digital Signal Processing



> "Techniques for digital signal processing are well guarded and held

> close to the chest, as they have valuable applications for multimedia

> content. The black art of Infinite Impulse Response ("IIR") filtering

> has remained veiled in secrecy with little publicly available source

> code...until now."










### What is this?



Building on the work of cherished luminaries such as Sophocles Orfanidis,

Andreas Antoniou, Martin Holters, and Udo Zolzer, this library harnesses

the power of C++ templates to solve a useful problem in Digital Signal

Processing: the realization of multichannel IIR filters of arbitrary order

and prescribed specifications with various properties such as Butterworth,

Chebyshev, Elliptic, and Optimum-L (Legendre) responses. The library is

provided under the MIT license and is therefore fully compatible with

proprietary usage.



Classes are designed as independent re-usable building blocks. Use some or

all of the provided features, or extend the functionality by writing your

own objects that plug into the robust framework. Only the code that you

need will get linked into your application. Here's a list of features:



- Exclusive focus on IIR filters instead of boring FIR filters

- Complete implementation of all "RBJ Biquad" Cookbook filter formulas

- Butterworth, Chebyshev, Elliptic, Bessel, Legendre designs

- Low Pass, High Pass, Band Pass, Band Stop transformations

- Low, High, and Band Shelf filter implementations for most types

- Smooth interpolation of filter settings, pole/zeros, and biquad

  coefficients to achieve seamless parameter changes

- Representation of digital filters using poles and zeros

- Realization using Direct Form I, Direct Form II, or user provided class

- Fully factored to minimize template instantiations

- "Design" layer provides runtime introspection into a filter

- Utility template functions for manipulating buffers of sample data

- No calls to malloc or new, great for embedded systems

- No external dependencies, just the standard C++ library!



Using these filters is easy:



    // Create a Chebyshev type I Band Stop filter of order 3

    // with state for processing 2 channels of audio.

    Dsp::SimpleFilter , 2> f;

    f.setup (3,    // order

             44100,// sample rate

             4000, // center frequency

             880,  // band width

             1);   // ripple dB

    f.process (numSamples, arrayOfChannels);



An accompanying demonstration program that works on most popular

platforms by using the separately licensed Juce application framework

(included), exercises all the functionality of the library, including

these features:



- Dynamic interface creates itself using filter introspection capabilities

- Audio playback with real time application of a selected filter

- Live time stretching and amplitude modulation without clicks or popping

- Charts to show magnitude, phase response and pole/zero placement

- Thread safety "best practices" for audio applications 



This is the provided DSP Filters Demo application, which demonstrates the

features of the library and uses the Juce application framework to run on

all popular platforms:






If you've been searching in futility on the Internet for some source code

for implementing high order filters, then look no further because this is

it! Whether you are a student of C++ or digital signal processing, a writer

of audio plugins, or even a VST synthesizer coder, "A Collection of Useful

C++ Classes for Digital Signal Processing" might have something for you!



### DSP Filters on the Web



DSP Filters Official Discussion Forum


http://www.kvraudio.com/forum/viewtopic.php?t=249926



DSP and Audio Plugin Discussion Forum


http://www.kvraudio.com/forum/viewforum.php?f=33



Juce Official Discussion Forum


http://www.rawmaterialsoftware.com/index.php



Juce Official Site


http://www.rawmaterialsoftware.com



### Terms and Conditions

DSP Filters Library and DSP Demo Application Copyright (c) 2009 by

[Vinnie Falco](http://github.com/vinniefalco)


Source code is provided under the

[MIT License](http://www.opensource.org/licenses/mit-license.php)


The [Juce Library](http://www.rawmaterialsoftware.com) is licensed

separately, from [Raw Material Software](http://rawmaterialsoftware.com).