3 Sep
2014
3 Sep
'14
5:54 p.m.
On Tue, Sep 02, 2014 at 04:12:29PM -0700, Kevin Cosgrove wrote:
I dug into this a bit more.
Getting the time & amplitude data out of the WAV file was easy with
sox file.wav -t dat - | tail -n +3 > file.dat
My beloved xgraph is not available on Fedora anymore. That made me
relearn gnuplot, a good move regardless. I wrote a script to build
a gnuplot input file, file.gpl, which contains something like
set terminal png notransparent nocrop
set output file.png
plot [] [-1:1] "file.dat" with lines
Then I run gnuplot on its input file like so
gnuplot file.gpl > file.png
I left out a lot of housekeeping related to my scripting. But, the
above does all of the work needed to produce a nice graph of my audio
files.
Of course, this isn't fast. It takes about 4 minutes on my
3.4GHz i7 with 16GB of RAM to create a plot from a 0.5GB mono WAV
file. Audacity and Ardour are faster than sox + gnuplot at creating
their waveform views. But, I can script with sox + gnuplot.
I hope this is useful for someone trolling the archive someday.
If the speed is important, Praat [1] also is a possible alternative.
There is a script in this message as a proof of concept.
Usage: ./sf2png [options] SNDFILE...
Write the images of the waveform of one or more soundfiles.
-h n heigth of the viewport [1.2].
-n suppress the plot annotations.
-s fontsize size of the font [4].
-w n width of the viewport [1.6].
Examples:
./sf2png /path/to/sndfiles/*.wav
The png files are in the same directory of the related soundfiles.
./sf2png -n -w 0.8 -h 0.5 /path/to/sndfiles/*.wav
./sf2png -w 4 -h 3 -s 5 /path/to/sndfiles/*.wav
[1] http://www.fon.hum.uva.nl/praat/
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#!/bin/bash
#
# Write the images of the waveform of one or more soundfiles.
usage() {
cat <<EOF
Usage: $0 [options] SNDFILE...
Write the images of the waveform of one or more soundfiles.
-h n heigth of the viewport [${height}].
-n suppress the plot annotations.
-s fontsize size of the font [${fontsize}].
-w n width of the viewport [${width}].
EOF
exit 1
}
write_img() {
local sndfile=$(realpath "$1")
local imgfile="${sndfile%%.*}.png"
echo "${sndfile} -> ${imgfile}"
#
# Warning: if there are trailing spaces after the copy-and-paste
# of this script, remember to remove at least the spaces after
# ${sndfile} and ${imgfile} in the follow praat script.
#
praat /dev/stdin <<EOF
Read from file... ${sndfile}
Select inner viewport... 0 $2 0 $3
Font size... $5
${inner_box}
Draw... 0 0 0 0 $4
Save as 300-dpi PNG file... ${imgfile}
EOF
}
main() {
local width="1.6"
local height="1.2"
local has_text="1"
local fontsize="4"
local inner_box=""
[ $# -lt 1 ] && usage
while getopts "h:ns:w:" arg; do
case "${arg}" in
h) height="${OPTARG}" ;;
n) has_text="0"
fontsize="1"
inner_box="Draw inner box"
;;
s) fontsize="${OPTARG}" ;;
w) width="${OPTARG}" ;;
*) usage ;;
esac
done
shift $(expr "${OPTIND}" - 1)
for sf in "$@"; do
if [[ ! -f "${sf}" ]]; then
echo "WARN: file ${sf} not found."
else
write_img "${sf}" "${width}"
"${height}" "${has_text}" \
"${fontsize}"
fi
done
}
main "$@"
tito