KlangWellen

KlangWellen is a C++ library for processing audio signals. each processor ( or class ) is designed around a central process method that either receives and/or emitts samples.

KlangWellen is an header-only library which should make it easier to integrate into projects.

compiling + running tests

to compile and run tests use the CLI as shown below ( example for klangwellen-to-wav + only tested on MacOS with Xcode installed ):

$ cd test/
$ clang++ -std=c++17 klangwellen-to-wav.cpp -I../include/ -I./ -o klangwellen-to-wav
$ ./klangwellen-to-wav # run test
$ afplay klangwellen-to-wav.wav # optionally playback WAV with afplay

or use the provided shellscript or

processor() interface

KlangWellen refrains from implementing process interfaces with the know C++ techniques¹. however, most processors supply a conceptual interface for processing signals in one or more of the following process methods:

1. float process() :: generate single mono signal
2. float process(float) :: single mono signal
3. void process(Signal&) :: single stereo signal
4. void process(float*, uint32_t) :: block of mono signals
5. void process(float*, float*, uint32_t) :: block of stereo signal

note, that 1. float process() only generates a signal. 2. float process(float) is encouraged to respect the input signal. however, in some cases ( in stereo signal generators ) it may overwrite the input signal regardless.

developers are encouraged to only implement the variants that make sense for a specific processors. developers are also encouraged to add a comment to the head of a processor marking those process methods are available with an [x].

/**
 * PROCESSOR INTERFACE
 *
 * - [ ] float process()
 * - [ ] float process(float)
 * - [ ] void process(Signal&)
 * - [ ] void process(float*, uint32_t)
 * - [ ] void process(float*, float*, uint32_t)
 */

Footnotes

1. i.e pure virtual functions ( i.e virtual float process() = 0; ) in a base class that are then used in a derived class ( i.e float process() override {} ). although this is the preferred object oriented programming (OOP) approach, my ( possibly faulty ) research has shown that there is a significant ( considering that the process function is called at very high frequencies ) performance decrease when working with virtual methods. this may not be as important on modern desktop machine but surely makes a difference on less powerful microcontroller-based platforms which definitely are a targeted platform for this library. ↩