SW_roverlink

Audio input and output testing on pi3

I used Pi3 Model B V1.2 and standard headset connected to a MPOW HC ADC USB adapter.

Notes:

• pyaudio-record.py and usb-audio-input.py do not run with python3, only pyhton and python 2

1. Connecting USB I/O device

   • The pi audio input/output is default set to ...rpi_simple_soundcard, which i believe is the GPIO pins and/or moniter in which it is connected depending on what the media player/method of playing audio decides.
   • You will need to configure the default device to our USB so that we don't have to manually change it everytime we connect and disconnect it https://makersportal.com/blog/2018/8/23/recording-audio-on-the-raspberry-pi-with-python-and-a-usb-microphone
   • check the usb is connected
   • setting up pyaudio

2. Checking the status of the devices

   • "cat /proc/asound/modules" should display 0 snd_usb_audio is what we are looking for, it will display as (index)(name of device)
   • if configurations edited correctly running "alsamixer", hitting the F6 sound card key will display as option 0
   • if the device index can not be changed, edit the program variables to match index of audio input device

3. Running the scripts requires a few more libraries and installs https://www.raspberrypi.org/forums/viewtopic.php?t=25173

   • another helpful link for setting up pyaudio aand streaming data https://code.google.com/archive/p/pygalaxy/wikis/SoundAnalyse.wiki

   • for import analyse

   • SoundAnalyse measures the loudness/pitch of the USB input in the example

   • Note: this converts the sound data into NumPy 16-bit mono array

   • pyaudio-record.py r

     • requires pyaudio, wave libraries
     • records audio for a brief moment and outputs to 'output.wav' file

   • usb-audio-input.py requires numpy, pyaudio, analyse

4. Checking the audio that was recorded

   • because my usb audio did not have output, I used the headphone jack and forced the audio to be player thru it using "omxplayer -local xxx.mp3"

More Information: https://people.csail.mit.edu/hubert/pyaudio/docs/ - the pyaudio documentation containing the original examle code - Input overflow error occured, resolved in 'usb-audio-input.py'

Common Issues/Solutions:

• updating the system using "sudo apt-get update" or "sudo rpi-update"
• IOError: [Errno -9996] Invalid input device means the audio device is not physically connected properly
• Input overflow error addressed in comments of 'usb-audio-input.py'
• Invalid number of channels is and easy fix: check the number of channels of the device and update the variable in the code accordingly, more at https://www.raspberrypi.org/forums/viewtopic.php?t=71062