Audio player component for esp32

Capabilities

• MP3 decoding (via libhelix-mp3)
• Wav/wave file decoding
• Audio mixing (multiple concurrent streams)

Who is this for?

Decode only audio playback on esp32 series of chips, where the features and footprint of esp-adf are not necessary.

What about esp-adf?

This component is not intended to compete with esp-adf, a much more fully developed audio framework.

It does however have a number of advantages at the moment including:

• Fully open source (esp-adf has a number of binary modules at the moment)
• Minimal size (it's less capable, but also simpler, than esp-adf)

Getting started

Examples

• esp-box mp3_demo uses esp-audio-player.
• The test example is a simpler example than mp3_demo that also uses the esp-box hardware.

How to use this?

esp-audio-player is a component on the Espressif component registry.

In your project run:

idf.py add-dependency chmorgan/esp-audio-player

to add the component dependency to the project's manifest file.

Dependencies

For MP3 support you'll need the esp-libhelix-mp3 component.

Tests

Unity tests are implemented in the test/ folder.

Audio Mixer

The Audio Mixer allows for concurrent playback of multiple audio streams. It supports two types of streams:

• Decoder Streams: For playing MP3 or WAV files. Each stream runs its own decoding task.
• Raw PCM Streams: For writing raw PCM data directly to the mixer.

Basic Mixer Usage

1. Initialize the mixer with output format and I2S write functions.
2. Create one or more streams using audio_stream_new().
3. Start playback on the streams.

audio_mixer_config_t mixer_cfg = {
    .write_fn = bsp_i2s_write,
    .clk_set_fn = bsp_i2s_reconfig_clk,
    .i2s_format = {
        .sample_rate = 44100,
        .bits_per_sample = 16,
        .channels = 2
    },
    // ...
};
audio_mixer_init(&mixer_cfg);

audio_stream_config_t stream_cfg = DEFAULT_AUDIO_STREAM_CONFIG("bgm");
audio_stream_handle_t bgm_stream = audio_stream_new(&stream_cfg);

FILE *f = fopen("/sdcard/music.mp3", "rb");
audio_stream_play(bgm_stream, f);

States

stateDiagram-v2
    [*] --> Idle : new(), cb(IDLE)
    Idle --> Playing : play(), cb(PLAYING)
    Playing --> Paused : pause(), cb(PAUSE)
    Paused --> Playing : resume(), cb(PLAYING)
    Playing --> Playing : play(), cb(COMPLETED_PLAYING_NEXT)
    Paused --> Idle : stop(), cb(IDLE)
    Playing --> Idle : song complete, cb(IDLE)
    [*] --> Shutdown : delete(), cb(SHUTDOWN)
    Shutdown --> Idle : new(), cb(IDLE)

Loading

Note: Diagram shortens callbacks from AUDIO_PLAYER_EVENT_xxx to xxx, and functions from audio_player_xxx() to xxx(), for clarity.

Release process - Pushing component to the IDF Component Registry

The github workflow, .github/workflows/esp_upload_component.yml, pushes data to the espressif IDF component registry.

To push a new version:

• Apply a git tag via 'git tag vA.B.C'
• Push tags via 'git push --tags'

The github workflow should run and automatically push to the IDF component registry.