audio notes

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Revision as of 04:48, 31 May 2015 by Root (Talk | contribs) (Play noise)

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Record audio from the microphone

arecord -vv -fdat recording.wav 

Using Sox (this works on OS X). This splits on silent gaps:

rec -r 44100 -b 16 -s -p silence 1 0.50 0.1% 1 10:00 0.1% \
    | sox -p audio_recording.wav silence 1 0.50 0.1% 1 2.0 0.1% :  newfile : restart

Playback audio OX X using Sox

Note that where an output filename is require you may substitute -d or -t coreaudio (for Mac OS X). These seem to be equivalent. The -d option seems to be the more general purpose style since it will automatically pick the correct sound output on a Mac and Linux.

Both examples below play audio and both will automatically detect the audio stream type. The play command is the easier to remember version. You may have special reasons for wanting to use the sox command alternative.

play audio_recording.wav
cat audio_recording.wav | sox - -t coreaudio

Play noise

These are all equivalent using /dev/urandom.

# From a file or device file.
sox -t raw -r 44100 -b 16 -e unsigned-integer /dev/urandom -d
sox -t raw -r 44100 -b 16 -e unsigned-integer /dev/urandom -t coreaudio
# Using a pipe...
cat /dev/urandom | sox -t raw -r 44100 -b 16 -e unsigned-integer - -d
cat /dev/urandom | sox -t raw -r 44100 -b 16 -e unsigned-integer - -t coreaudio

This uses Sox's built-in noise generator:

play -n synth whitenoise