plot audio data in gnuplot -

how convert audio file such aiff svg using gnuplot? used sox (sound exchange) convert .aiff .dat, can load in gnuplot.

i did similar to:

set terminal svg set output "test.svg" plot "test.dat" 

i svg file, dots / or lot of x. how connect dots?

to draw lines between points, use

plot "test.dat" lines 

or keep point markers lines, use

plot "test.dat" linespoints 

so example becomes

set terminal svg     set output "test.svg" plot "test.dat" lines 

further tips:

don't consider every sample:

with large files may find useful plot every nth sample "every n". make plot faster generate , yield smaller (but less detailed) svg file.

e.g.

plot "test.dat" every 100 lines 

ignore .dat file header:

if sox-produced .dat file has lines of introductory metadata, such as

; sample rate 44100 ; channels 2 

you can add following have gnuplot consider lines comments , ignore them.

set datafile commentschars ";" 

this save having pre-process .dat file in order remove lines before gnuplot chokes on them.

plot both left , right channels of stereo audio:

if you're working stereo file, want see both channels.

we can use "multiplot" lay out following 2 plots (of left right channel) 1 above other on shared x-axis, many sound-editing programs do.

set multiplot layout 2,1 plot "test.dat" using 1:2 lines plot ""         using 1:3 lines 

the 1:2 , 1:3 instruct gnuplot columns of dat file use x , y sources. i'm assuming stereo .dat file produced sox looks mine does, columns - 1: time since beginning of first sample - 2: normalized sample value of left channel - 3: normalized sample value of right channel

example snippet:

   10.840113       0.20101929      0.17840576     10.840136       0.26062012      0.14831543     10.840159       0.23779297      0.13146973  

putting together: here's script puts of above together. if don't have stereo data file try with, you'll want remove plot of 1:3 , multiplot setting.

#!/usr/bin/env gnuplot set datafile commentschars ";"  set terminal svg set output "test.svg"  set multiplot layout 2,1 plot "test.dat" using 1:2 every 100 lines plot ""         using 1:3 every 100 lines unset multiplot 

prettification

finally, i've tweaked script presentation (borrowing heavily excellent "gnuplot in action" book philipp k. janert):

#!/usr/bin/env gnuplot set datafile commentschars ";"  set terminal svg set output "test.svg"  set multiplot layout 2,1  set ylabel "sample value" set bmargin 0 set format x "" set ytics -0.8,0.2 set key bottom plot "test.dat" using 1:2 every 100 lines lc rgbcolor "#a0a0b0" title "left channel"  set xlabel "time (s)" set bmargin set tmargin 0 set format x "%g" set ytics -1.0,0.2,0.8 set key top  plot ""         using 1:3 every 100 lines lc rgbcolor "#a0a0b0" title "right channel" unset multiplot 

here's example output (albeit png):

how make .dat file

for following along @ home, can use sox generate .dat file audio file following command:

sox input.wav output.dat 

big file warning: converting 10 seconds of stereo audio @ 40khz produce 25mb output file.