In this final lesson in the module, you will explore the structure of an effect plugin, learn about developing code using Klang Studio, and draw on what you have learnt about code and digital signal processing (DSP) to implement a gain (level) effect plugin.

LESSON PLAN

• Understand the code structure of audio effect plugins.
• Explore coding practices and tools (using Klang Studio).
• Apply your knowledge of basic digital signal processing (DSP).
• Build a gain (level/volume) effect plugin.

INSTRUCTIONS

Use the < > arrow(s) above to move through the topic. Each page explains a key concept using text and graphics, leading up to a practical task. You can return to any page at any time, using the arrows or ▼ drop-down menu, and also restart animations by simply clicking them.

Together, the two lines from the previous lesson form the process() function of our plugin,
which describes the audio process applied to every input sample to produce the output.

Functions are named, reusable blocks of code defined for a specific purpose, called as needed. The process() function is triggered during DAW playback, called repeatedly
to apply the audio process to every input sample (e.g. 44,100 times a second).

A fundamental concept in programming, functions allow us to structure code, and break complex programs down into simpler, more modular parts — abstracting complexity.

Code to define the function is contained in curly brackets, known as { braces }, which are used to mark the beginning and end of functions, objects, and other code structures in C++.

Unmatched braces (opening but no closing brackets, or vice versa) are another
common and easy mistake to make - but much harder for the compiler to catch!

Code to define the function is contained in curly brackets, known as { braces }, which are used to mark the beginning and end of functions, objects, and other code structures in C++.

Unmatched braces (opening but no closing brackets, or vice versa) are another
common and easy mistake to make - but much harder for the compiler to catch!

To make it easier to see the structure (and ensure brackets are matched), it's important
to indent the code inside braces - using tab ⇥ or a fixed number of spaces (e.g. 3).

The process() function is one part of the wider plugin, encapsulated by the MyEffect object.

An object (struct or class in C++) is a named, reusable code structure that can contain multiple variables, functions, or other objects, oriented around a specific purpose.

Objects are a core concept of C++, which is designed for object-oriented programming — the principle of reducing large, complex systems to simpler, modular, self-contained parts that logically mirror the world being modelled and can be developed and tested separately.

MyEffect inherits the functionality of a generic Effect object, which includes all the base code for an effect plugin, so that we can focus on the audio processing and the UI.

We define the UI for our plugin in the object's constructor — a special function sharing the name of the object, called when it is created (when the plugin loads) to initialise itself.

In this instance, we'll define controls so that our UI contains a single Dial called "Gain",
(with the default range, 0.0 to 1.0), which we can then access in process() using controls[0]:

The last remaining code required are two lines that add the Klang extension
to C++ and tell it to use the performance optimised versions of DSP objects.

We'll use these in all projects, so will generally omit them in these examples.

We now have the complete source code for the gain effect, but before we move to Klang Studio to compile the plugin, there's one last programming tool to introduce: commenting.

Comments allow you to annotate and decorate your code, and write descriptions or notes
to yourself (and others). Anything after // is treated as a comment, rather than code.

On the course, you should annotate code with comments to help you remember how code works. You can also 'comment out' code to disable it, which can be useful for finding bugs!

Klang Studio is a complete C++ interactive developer environment (IDE) contained in an audio plugin, enabling you to develop synthesisers and effects live inside the DAW itself.

Use the guidance below to create a new project, add code, and build the gain plugin
then discover the different parts and features of Klang Studio by exploring the program.

#include <klang.h>
using namespace klang::optimised;

struct Gain : Effect {

	Gain() { 
		controls = { 
			Dial("Gain") 
		};
	}

	void process() { 
		param gain = controls[0];
		in * gain >> out;
	}

};

Use the guidance below to create a new project, add code, and build the gain plugin
then discover the different parts and features of Klang Studio by exploring the program.

#include <klang.h>
using namespace klang::optimised;

struct Gain : Effect {

	Gain() { 
		controls = { 
			Dial("Gain")
		};
	}

	void process() { 
		param gain = controls[0];
		in * gain >> out;
	}

};