#! /bin/zsh

 

# use once:

#

#     a-level t

#

# continous: invoke with signal USR1;

#            terminate with C-c C-c

#

#     a-level

#     kill -s USR1 PID

 

# should be faster than 300 ms

do-a-level () {

    (($#)) || (($+AUDIO_OUTPUT)) || set /dev/stdout

    rec --null stat trim 0 0.1 2>&1 | \

        grep 'Maximum amplitude'    | \

        cut -d' ' -f 7 >> $1

}

 

trap 'do-a-level' USR1

 

(($+1)) && do-a-level || while ((1)) {}