Audio

The 825 has an audio line out port. Powered speakers may be plugged into this port to allow for high quality stereo audio output. The audio output 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)

card825gen2:~$ 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

card825gen2:~$ 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

card825gen2:~$ 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

card825gen2:~$ 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

card825gen2:~$ 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:

card825gen2:~$ gst-launch-1.0 playbin uri=file:///run/media/Data-sda1/sample-12s.mp3

App may be written to output audio by using system calls to perform commands such as above. However, it would be better to use gstreamer library calls in the app. An example of this will be added to this page at a later date.