gst-awkward

A small gstreamer application that plays music, but shuts up whenever someone speaks. Quit awkward silences today!

Usage

• Match dependencies:
  • Gstreamer
  • Alsa-utils [optional]: apt install alsa-utils
  • Gnuplot [optional]: apt install gnuplot
• Clone this repo git clone https://github.com/pabsan-0/gst-awkward
• Set your device configuration in the src/main.c #defines
• Build the tool: make
• Run the app with ./main.o

The audio essentials

• Audio loopback sudo modprobe snd-aloop
• List mic-like devices arecord -l
• List speaker-like devices aplay -l
• Hardware spec: hw:x,y,z hw:card,device,subdevice
  • x: Card
  • y: Device
  • z: Subdevice
• Gstreamer elements:
  • alsasink, alsasrc: Advanced Linux Sound Architecture
  • audioconvert
  • volume, level: for setting/reading levels
  • decodebin, autovideosink, autovideosrc

Snippets:

# Playing audio file in a loop
gst-launch-1.0 multifilesrc loop=1 location=media/short.mp3 ! decodebin ! audioconvert ! alsasink

# Introducing delay
gst-launch-1.0 audiotestsrc ! queue max-size-buffers=0 max-size-time=0 max-size-bytes=0 min-threshold-time=1000000000000 ! autoaudiosink

# Mic to speaker with native delay (fractions of a sec)
gst-launch-1.0 alsasrc device="hw:3,0,0" ! alsasink 

# Mic to speaker fancier
gst-launch-1.0 alsasrc device="hw:3,0,0" ! volume volume=1.5 ! level message=TRUE ! alsasink 

Links

• Linux audio 101 small tutorial TheSalarKhan/Linux-Audio-Loopback-Device
• On introducing delay on a pipeline https://stackoverflow.com/a/17218113
• Level plugin example https://github.com/krad-radio/gstreamer-plugins-good-krad/blob/master/tests/examples/level/level-example.c

Acknowledgements

• Song bit from The Engagement by Silent Partner: https://www.youtube.com/watch?v=_TcAQEufZcU