AUDIO

This section describes how to use GPIO to drive audio functions on the Raspberry Pi, laying the foundation for subsequent project development.

AUDIO Operations

Check Audio Devices

danger

The module must be connected before powering on to be properly recognized.

Check currently recognized audio playback devices
```
aplay -l
```

Audio Playback

Play the audio file test.wav (using the corresponding device; here the recognized audio device is hardware sound card number 2). Ensure the test.wav file exists in the current directory.
```
aplay -D plughw:2 test.wav
```
The speaker or headphones will then play the audio.

alsamixer Audio Configuration

alsamixer Graphical Configuration

Open the alsamixer audio configuration tool
```
sudo alsamixer
```
If the sound card is not set as the default, press F6 to select the sound card device.
Use the left/right arrow keys to select functions and the up/down arrow keys to adjust the corresponding volume.
Use shortcut commands to configure; download the relevant configuration file

After entering the downloaded file path in the terminal, choose and execute one of the following commands to load one of the provided .state snapshots:

sudo alsactl restore -f ./All-input-output.state            # Enable all input and output interfaces
sudo alsactl restore -f ./Headphone-input-output.state      # Enable TRRS headphone input/output, disable other interfaces
sudo alsactl restore -f ./OnBoard-MIC1-input.state          # Enable onboard microphone 1, disable other interfaces
sudo alsactl restore -f ./OnBoard-MIC2-input.state          # Enable onboard microphone 2, disable other interfaces
sudo alsactl restore -f ./Dual-speaker-output.state         # Enable dual-channel speaker output, disable other interfaces

After executing the appropriate command, the corresponding interfaces can be used. The error log shown below is normal.
Open the alsamixer audio configuration tool, press F6 to select the sound card device, and verify the snapshot configuration.
```
sudo alsamixer
```

Quickly Generate Multi-Interface Snapshots Based on Provided Snapshots

warning

The merge tool is for simple use only; some features cannot be achieved simply by merging.

Download the relevant configuration file. The package includes a Python program to merge multiple snapshots. You can configure which interfaces to enable as needed.

Generate a .state snapshot that enables both onboard microphone 1 and headphones:

python3 merge_alsa_states.py -o merged1.state OnBoard-MIC1-input.state Headphone-input-output.state

Generate a .state snapshot that enables all onboard interfaces simultaneously:

python3 merge_alsa_states.py -o merged.state  Headphone-input-output.state OnBoard-MIC1-input.state OnBoard-MIC2-input.state Dual-speaker-output.state

Command breakdown:
```
python3 merge_alsa_states.py -o merged1.state OnBoard-MIC1-input.state Headphone-input-output.state
```
- The filename after -o is the name of the merged snapshot; you can choose any name, as long as it ends with .state.
- After the custom merged snapshot name, list the snapshots to be merged. You are not limited to two; you can include multiple snapshots, provided they exist in the current folder.

Play MP3

aplay only supports WAV audio. In practice, MP3 format audio is more common. Install the mpg123 playback tool.
```
sudo apt-get install mpg123 
```
Play the music.mp3 audio file. Ensure the music.mp3 file exists in the current directory.
```
sudo mpg123 music.mp3
```

Graphical Configuration

Install the graphical audio control tool smplayer
```
sudo apt-get install smplayer
```
Right-click in the interface and select IQaudIODAC as the default.

Give Feedback

AUDIO Operations​

Check Audio Devices​

Audio Playback​

alsamixer Audio Configuration​

alsamixer Graphical Configuration​

Quickly Generate Multi-Interface Snapshots Based on Provided Snapshots​

Play MP3​

Graphical Configuration​