30 Aug
2014
30 Aug
'14
11:26 a.m.
I have a huge number (about 2400) of 0.5GB WAV files from live 24
track recordings. 10-40% of the tracks on some recording sets
are not needed, an unused vocal mic stashed off stage. I have
been using the RMS function in SOX by command line to help me
determine which files are not useful. A low RMS level tends to
indicate less usable signal.
But, this doesn't always work. For instance, it can miss that
great minute long harmonica solo during the hour long show.
Peak levels don't help, because frequently a drummer will slam
something loudly enough to falsely mark the file as useful, when
it's actually not.
Looking at the audio waveform with Ardour or Audacity seems
foolproof. But, it's also way too much work to use a GUI
application on that many files.
I would like to run a script or program on the set of files and
produce something like an Audacity or Ardour waveform graphic to
be stored in a PNG (or similar) associated file. Does anyone
know of something close to out-of-the-box ready to do this?
I did find these possibly helpful links.
http://www.network-theory.co.uk/docs/octave3/octave_263.html
https://wiki.ubuntu.com/Waveform_Viewers-Plotting_Large_Analog_Data
Thanks...
--
Kevin
3 Sep
3 Sep
1:12 a.m.
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.
Cheerio...
--
Kevin
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/
<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><
#!/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
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linux-audio-user@lists.linuxaudio.org
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Kevin Cosgrove -
Tito Latini