Audio

The 825 has an audio line out port. This is allows high quality stereo audio output. This is independent from the beeper.

The command line utility aplay may be used to play wav files to the audio output, for example: (For this example audio files are placed on a flash drive in directory wav_files auto mounted as /run/media/sda1)

# aplay /run/media/sda1/wav_files/BOUNCEIN.WAV
Playing WAVE '/run/media/sda1/wav_files/BOUNCEIN.WAV' : Signed 16 bit Little Endian, Rate 22050 Hz, Mono
# aplay /run/media/sda1/wav_files/BOING.WAV
Playing WAVE '/run/media/sda1/wav_files/BOING.WAV' : Signed 16 bit Little Endian, Rate 22025 Hz, Mono
# aplay /run/media/sda1/wav_files/BOUNCE.WAV
Playing WAVE '/run/media/sda1/wav_files/BOUNCE.WAV' : Signed 16 bit Little Endian, Rate 22025 Hz, Mono
# aplay /run/media/sda1/wav_files/HAPPY.WAV
Playing WAVE '/run/media/sda1/wav_files/HAPPY.WAV' : Signed 16 bit Little Endian, Rate 22050 Hz, Mono
# aplay /run/media/sda1/wav_files/MELT.WAV
Playing WAVE '/run/media/sda1/wav_files/MELT.WAV' : Signed 16 bit Little Endian, Rate 22050 Hz, Mono
#

Gstreamer may be used to play an mp3 audio file:

root@imx8mq-var-dart:/run/media/Data-sda1# gst-launch-1.0 playbin uri=file:///run/media/Data-sda1/sample-12s.mp3