Arduino Audio Tools

Some basic header-only C++ classes that can be used for Audio Processing provided as Arduino Library:

a simple I2S class (to read and write to the internal I2S)
a simple ADC class (to read analog data with the help of I2S)
a simple PWM class (to write audio data with the help of PWM)
Additional Stream implementations: MemoryStream, URLStream, I2SStream, A2DPStream, PrintStream etc
Support for different Encoders and Decoders for AAC, MP3 and WAV
Converters
Musical Notes (with frequencies of notes)
SineWaveGenerator (to generate a sine tone) and Mozzi for more complex scenario
Different buffer implementations
TimerAlarmRepeating (e.g. for sampling audio data using exact times) [ESP32 only]
AudioOutputWithCallback class to provide callback integration e.g. with ESP8266Audio
Desktop Integration: Building of Arduino Audio Sketches to be run on Linux, Windows and OS/X

This functionality provides the glue which makes different audio processing components and libraries work together. We also provide plenty of examples that demonstrate how to implement the different scenarios. The design philosophy is based on the Arduino conventions: we use the begin() and end() methods to start and stop the processing and we propagate the use of Streams. We all know the Arduino Streams: We usually use them to write out print messages and sometimes we use them to read the output from Serial devices. The same thing applies to “Audio Streams”: You can read audio data from “Audio Sources” and you write them to “Audio Sinks”.

As “Audio Sources” we will have e.g.:

Analog Microphones – AnalogAudioStream
Digital Microphones – I2SStream
Files on the Internet – URLStream
Generated Sound – GeneratedSoundStream
Mobile Phone A2DP Bluetooth – A2DPStream
Binary Data in Flash Memory – MemoryStream
Audio generated by STK Framwork - STKStream
Desktop Integration - PortAudioStream
Any other Arduino Classes implementing Streams: SD, Ethernet etc

As “Audio Sinks” we will have e.g:

external DAC – I2SStream
with an Amplifier – AnalogAudioStream
with a Piezo Electric Element – PWMAudioStream
Bluetooth Speakers – A2DPStream
Serial to display the data as CSV – CsvStream
Encoding and Decoding of Audio EncodedAudioStream
Desktop Integration - PortAudioStream
ID3 Metadata for MP3 - MetaDataID3
Any other Arduino Classes implementing Streams: SD, Ethernet etc

Here is an simple example which streams a file from the Flash Memory and writes it to I2S:

#include "AudioTools.h"
#include "StarWars30.h"

using namespace audio_tools;  

uint8_t channels = 2;
uint16_t sample_rate = 22050;

MemoryStream music(StarWars30_raw, StarWars30_raw_len);
I2SStream i2s;  // Output to I2S
StreamCopy copier(i2s, music); // copies sound into i2s

void setup(){
    Serial.begin(115200);

    I2SConfig config = i2s.defaultConfig(TX_MODE);
    config.sample_rate = sample_rate;
    config.channels = channels;
    config.bits_per_sample = 16;
    i2s.begin(config);
}

void loop(){
    if (!copier.copy()){
      i2s.end();
      stop();
    }
}

Examples

Further examples can be found in the Wiki. The library also provides a versatile AudioPlayer.

Logging

The application uses a built in logger (see AudioLogger.h and AudioConfig.h). You can e.g. deactivate the logging by changing USE_AUDIO_LOGGING to false in the AudioConfig.h:

#define USE_AUDIO_LOGGING false
#define LOG_LEVEL AudioLogger::Warning
#define LOG_STREAM Serial

Per default we use the log level warning and the logging output is going to Serial. You can also change this in your sketch by calling AudioLogger begin with the output stream and the log level e.g:

AudioLogger::instance().begin(Serial, AudioLogger::Debug);

Optional Libraries

Dependent on the example you might need to install some of the following libraries:

ESP32-A2DP Library to support A2DP Bluetooth Audio
arduino-libhelix A MP3 and AAC Decoder from Realnetworks
arduino-fdk-aac A AAC Encoder and Decoder from the Frauenhofer Institute
arduino-libmad A open source MP3 Decoder from Underbit
arduino-liblame A open source MP3 Encoder
SdFat Library to read and write files supporting SD cards with FAT16/FAT32 and exFAT
SD Library to read and write files supporting SD cards with FAT16 and FAT32
SAM A Text to Speach Engine
TTS A Text to Speach Engine
flite A Text to Speach Engine
arduino-stk Synthesis ToolKit in C++ (STK)
Mozzi A sound synthesis library for Arduino
ESP8266Audio to play different audio Formats

After installing a library, you might need to activate it's usage in the AudioConfig.h file!

Documentation

Here is the generated Class Documentation.
Please also check out the Information in the Wiki
You also might find further information in one of my Blogs

Installation in Arduino

You can download the library as zip and call include Library -> zip library. Or you can git clone this project into the Arduino libraries folder e.g. with

cd  ~/Documents/Arduino/libraries
git clone pschatzmann/arduino-audio-tools.git

If you want to use the library in PlatformIO, you can find a detailed description in the Wiki.

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