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AUDIO

This section describes how to use the USB audio function on the Raspberry Pi, laying the foundation for subsequent project development.

AUDIO Operations​

Check Audio Devices​

  • Check currently recognized audio playback devices 
    aplay -l
  • Check currently recognized audio recording devices 
    arecord -l
    Query Current Audio Device

Audio Recording​

  • Record a 2‑second audio clip and save it as test.wav in the current directory (using the corresponding device; here the recognized audio device is hardware sound card number 2) 
    sudo arecord -D hw:2,0 -f S32_LE -r 16000 -c 2 test.wav
  • After recording finishes, view the generated file 
    ls

Audio Playback​

  • Play the audio file test.wav (using the corresponding device; here the recognized audio device is hardware sound card number 2). Make sure the file exists in the current directory; if not, generate it by following the Audio Recording step above 
    sudo aplay -Dhw:2 test.wav
  • The speaker or headphones will then play the audio

Audio Input/Output Test​

  • Loopback test (the sound collected by the microphone will be heard through the headphones or speaker)
  • Note: Keep the speaker away from the microphone to avoid feedback howling. 
    sudo arecord -f cd -Dhw:2 | aplay -Dhw:2
    • arecord -f cd Dhw:2: Use hardware sound card number 2 for recording, with CD standard format
    • aplay -Dhw:2: Output the audio to hardware sound card number 2