Workbench Library

Overview

The Workbench library provides a cookiecutter for audio and MIDI processing using PortAudio and PortMidi. It includes functionality for initializing, configuring, and handling audio and MIDI input/output, along with utilities for logging and configuration management.

Prerequisites

Before using the Workbench library, ensure you have the following prerequisites installed on your system:

• PortAudio: A cross-platform, open-source audio library.
• PortMidi: A library for MIDI input and output.
• C Compiler: A C compiler such as gcc or clang.
• Pkg-config: A helper tool used to configure compiler and linker flags for libraries.

Installation

Ensure that you have PortAudio and PortMidi installed on your system. You can install these libraries using your package manager. For example, on Mac, you can install them using:

brew install pkg-config portaudio portmidi

Compilation The Workbench library uses a Makefile to manage the build process. Below are the steps to compile the library and examples.

1. Clone the Repository

   Clone the repository containing the Workbench library source code:

git clone https://github.com/cyrillsemenov/audio-midi-workbench
cd audio-midi-workbench

1. Build the Library and Examples

   Run the following command to build the library and examples:

make

This command will compile the library and examples, placing the output binaries in the bin directory.

1. Generate Documentation

   If you have Doxygen installed, you can generate the documentation using:

make docs

1. Clean the Build

   To clean the build directory, removing all compiled files, run:

make clean

Usage

Here are some basic usage examples to help you get started with the Workbench Audio and MIDI project.

Audio

#include "workbench.h"
 
Config *cfg;
 
void my_audio_callback(const void *input_buffer, void *output_buffer, unsigned long block_size, void *user_data) {
    const AudioSample_t *in = (const AudioSample_t *)input_buffer;
    AudioSample_t *out = (AudioSample_t *)output_buffer;
 
    // Process audio data here
}
 
int main(int argc, char **argv) {
  cfg = config_init(argc, argv, &my_audio_callback, NULL, NULL);
  while (true) {
    Pa_Sleep(1000);
  }
  return 0;
}

MIDI

#include "workbench.h"
 
Config *cfg;
 
int my_midi_callback(const void *input_buffer, void *output_buffer, unsigned long block_size, void *user_data) {
    const PmEvent *in_buffer = (const PmEvent *)in;
    PmEvent *out_buffer = (PmEvent *)out;
    int out_len = 0;
 
    // Process MIDI data here
 
    return out_len;
}
 
int main(int argc, char **argv) {
  cfg = config_init(argc, argv, &my_audio_callback, NULL, NULL);
  while (true) {
    // Use porttime sleep function instead of portaudio
    Pt_Sleep(1000);
  }
  return 0;
}

Configuration

Workbench parameters have default values, which can be overridden by values set in a config file or command line arguments.

Values have this priority:

1. Default parameters
2. Values from the config file override default values
3. Values from command line arguments override values from the config file

Config File

Create a text file (e.g., config.yml) that contains the configuration settings.

Example config.yml:

# Configuration for the application
midi_input: my_midi_input_device
midi_output: my_midi_output_device
midi_buffer_size: 512
audio_input: my_audio_input_device
audio_output: my_audio_output_device
sample_rate: 44100
block_size: 1024
in_channel_count: 1
out_channel_count: 2

Command Line Arguments

When running the application, you can pass command line arguments to override the config file settings or to provide additional options.

Example command line:

./my_application --config=config.txt --midi_input=my_midi_input_device --sample_rate=48000

This will use the config.txt file for initial settings but will override the midi_input and sample_rate settings from the command line arguments.

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