set term png

set output "kadai1.png"

fs = 16000.0

set xlabel "time [msec]"
set ylabel "amplitude"

set xrange [0:30]
set yrange [-1:1]

set size ratio 0.3

plot "sample01.sw" binary format="%int16" every ::::479 \
    using ($0 * 1000.0 / fs):($1/32767.0) \
    with lines notitle