Some basic header-only C++ classes that can be used for Audio Processing provided as Arduino Library:
- We provide different "Audio Sources" and "Audio Sinks" (see next section)
- Support for different Encoders and Decoders for AAC, MP3 and WAV
- Different Sound Generators (e.g. to generate a sine tone)
- Support for Sound Effects with different Effect Implementations (e.g. Boost, Distortion, Echo, Reverb...)
- Different Buffer Implementations
- Different Converters and Filters
- Musical Notes (with frequencies of notes)
- A Repeating Timer (e.g. for sampling audio data using exact times)
- 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
- Streaming Internet Radios - ICYStream
- Generated Sound – GeneratedSoundStream
- Mobile Phone A2DP Bluetooth – A2DPStream
- Binary Data in Flash Memory – MemoryStream
- Audio generated by STK Framwork - STKStream
- Desktop Integration - PortAudioStream
- A Timer based Source - TimerCallbackAudioStream
- ESP32 AudioKit - AudioKitStream
- Filtered Input - FilteredStream
- Any other Arduino Classes implementing Streams: SD, Ethernet etc
As “Audio Sinks” we will have e.g:
- external DAC – I2SStream
- Analog output e.g. with an Amplifier – AnalogAudioStream
- with a Piezo Electric Element – PWMAudioStream
- external SPDIF/TOSLINK Amplifier - SPDIFStream
- 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
- A Timer based Sink - TimerCallbackAudioStream
- ESP32 AudioKit - AudioKitStream
- Callback integration e.g. with ESP8266Audio AudioOutputWithCallback
- Filtered Output - FilteredStream
- 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"
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);
auto 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();
}
}
Each stream has it's own configuration object that should be passed to the begin method. The defaultConfig() method is providing a default proposal which will usually "just work". Please consult the class documentation for the available configuration parameters. You can also easily adapt any provided examples: If you e.g. replace the I2SStream with the AnalogAudioStream class, you will get analog instead of digital output.
Further examples can be found in the Wiki. The library also provides a versatile AudioPlayer.
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);
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
- arduino-audiokit Support for the ESP32 AudioKit and ES7148, ES7210, ES7243, ES8311, ES8347, ES8388, TAS5805m decoder chips
- arduino-midi A simple MIDI message parser and generator
- 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
- simple-tts A Simple TTS engine which is based on prerecorded audio (Talking Clock, Talking Numbers)
- arduino-stk Synthesis ToolKit in C++ (STK)
- Maximilian cross-platform and multi-target audio synthesis and signal processing library
- 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!
- 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
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
I recommend to use git because you can easily update to the latest version just by executing the git pull command in the project folder.
If you want to use the library in PlatformIO, you can find a detailed description in the Wiki.