A Simple Streaming Audio Player
It was pretty simple to build a simple audio player with the help of the Stream API.
The AudioPlayer supports
- multiple processor architectures
- multiple audio data sources (SD, URL, callbacks)
- different Output Scenarios (I2S, PWM, A2DP etc). Just pass the desired output stream object to the constructor.
- different Decoders for MP3, AAC, WAV. Just pass the desired decoder object to the constructor.
- Volume Control (by calling player.setVolume())
- Stopping and Resuming the processing (by calling player.stop() and player.play())
- You can move to the next file by calling player.next();
- support for Metadata
The example demonstrates how to implement an MP3 Player which provides the data via the Internet (with the help of the AudioSourceURL class) and sends the audio via I2S to an external DAC using an ESP32.
The External DAC
For my tests I am using the 24-bit PCM5102 PCM5102A Stereo DAC Digital-to-analog Converter PLL Voice Module pHAT
I am just using the default pins defined by the framework. However I could change them with the help of the config object. The mute pin can be defined in the constructor of the I2SStream - by not defining anything we use the default which is GPIO23
| DAC | ESP32 |
|---|---|
| VCC | 5V |
| GND | GND |
| BCK | BCK (GPIO14) |
| DIN | OUT (GPIO22) |
| LCK | BCK (GPIO15) |
| FMT | GND |
| XMT | 3V (or another GPIO PIN which is set to high) |
- DMP - De-emphasis control for 44.1kHz sampling rate(1): Off (Low) / On (High)
- FLT - Filter select : Normal latency (Low) / Low latency (High)
- SCL - System clock input (probably SCL on your board).
- FMT - Audio format selection : I2S (Low) / Left justified (High)
- XMT - Soft mute control(1): Soft mute (Low) / soft un-mute (High)
Wiring the Volume Potentiometer
| Pot | ESP32 | ESP8266 |
|---|---|---|
| POW | 3V | 3V |
| GND | GND | GND |
| VOUT | A0 | A0 |
Moving to the next song
We use a button to move to the next url.
| Button | ESP32 | ESP8266 |
|---|---|---|
| Button | GPIO13 | GPIO13 |
| Out 3V |