Arduino: Streaming MP3 Files to a Bluetooth Speaker

In the last Blogs I presented
– A File Based Versatile MP3 Player
– A Streaming MP3 Player
– A Streaming AAC Player with Volume Control

All these examples were using my Arduino Audio Tools Library.

In this final Blog about this topic, I will demonstrate how easy it is to adapt the Sketch from the first Blog and send the output to a Bluetooth Speaker. Here is the Arduino Sketch which will work with a ESP32 Microcontroller:

#define USE_HELIX 
#define USE_A2DP
#define USE_SDFAT

#include "AudioTools.h"
#include "AudioA2DP.h"
#include "AudioCodecs/CodecMP3Helix.h"

using namespace audio_tools;  

const char *startFilePath="/";
const char* ext="mp3";
AudioSourceSdFat source(startFilePath, ext);
A2DPStream out = A2DPStream::instance();  // A2DP output - A2DPStream is a singleton!
MP3DecoderHelix decoder;
AudioPlayer player(source, out, decoder);


void setup() {
  Serial.begin(115200);
  AudioLogger::instance().begin(Serial, AudioLogger::Warning);

  // setup output - We send the output via A2DP to a "LEXON MINO L" Bluetooth Speaker
  auto cfg = out.defaultConfig(TX_MODE);
  cfg.name = "LEXON MINO L";
  out.begin(cfg);

  // setup player
  player.setVolume(0.1);
  player.begin();

}

void loop() {
  player.copy();
}

The only difference is that we use the A2DPStream class as output and when we configure A2DP, we need to indicate the Bluetooth Speaker name.
Finally we limit the volume and set it to 0.1.

Audio Format

The Helix decoder provides 2 channels with 16bit data usually at a sample rate of 44100 and this is exactly what is needed by A2DP!

SD Card

Here is the information how to wire the SD card to the ESP32

Dependencies

You need to install the following libraries:

• arduino-audio-tools
• arduino-libhelix
• SdFat
• ESP32-A2DP

Source Code

The full (actual) source code can also be found on Github