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Notes on Sound and Audio

Master volume

This turns off and on the master volume switch in Linux from the command-line. This is useful for scripting.

amixer sset Master off
amixer sset Master on

Play raw audio -- make noise

This shows how to play a raw audio byte stream of 44.1 kHz, 16-bit, single channel, unsigned integer. In this example the file, entropy-source.bin, is a binary file of random bytes. Since this is noise it hardly matters how fast the data is played back.

play -t raw -r 44100 -b 16 -c 1 -e unsigned-integer entropy-source.bin
play -t raw -r 44100 -b 16 -c 1 -e unsigned-integer /dev/urandom

This gives playback at a lower sample bitrate and sample bit size, 8 kHz, 8-bit, single channel, unsigned integer. This plays the binary from the play binary itself.

play -t raw -r 8000 -b 8 -c 1 -e unsigned-integer $(type -p play)