Re: [SoX-users] convert mp3 to .txt file - 1

[Fmiser <fm...@gm...>]

> > Philip wrote:
> >
> > This one-liner runs on my Linux computer.
> >
> > "sox" converts the audio to 8 kHz sample rate, 8 bit depth,
> > mono. "od" dumps the raw values.
> > "cut" trims the first 9 characters off each line 'cause they
> >  are not audio levels
> > "sed" removes extra spaces and then inserts a comma.
> > "tr" removes the linefeeds so it becomes one long line.
> > 
> > sox in.wav -b 8 -c 1 -r 8000 -t raw - |\
> > od -t u1 -v - |\
> > cut -c 9- |\
> > sed -e 's/\  / /g' -e 's/   / /g' -e 's/ /,/g' |\
> > tr '\n' ',' > out.file

> Hendrikus Godvliet wrote:
> 
> I am curios for what do you need this text data or what are
> you doing with this text data?
> I mean is it possible to change the audio data by change the
> data in the text file and to convert it back in a .wav?

Yes,  I suppose you could.  But I don't have a command to make
audio again.

My project was quite different. 

I work with a local drama group and we were doing the play
"You Can't Take It With You".  One scene calls for a small
firework that can be lit on a kitchen table and called "red
fire".  Because of the dangers of real pyrotechnics inside a
building we decided to fake it.  I build three sets of bright
red LEDs, mounted them to magnets, attached the magnets to the
side of a cast iron pot.  The actor sets the pot on the table
and the LEDs shine on his face.  Because the pot is tall
enough, the audience can't see the LEDs, only the red light on
the actor.

But steady light won't look like a sputtering firework thing -
so we used an Arduino microcontroller to independently drive
the three channels of LEDs using pulse width modulation.  The
PWM needs an 8 bit value.  We first tried random, which worked
but didn't look right. So I took the sound of a sparkler
sputtering, processed the audio a bit (lots of dynamic range
compression, then applied the equivalent of a DC offset so the
0% values became 50%), then ran it through the above command
to get values for a large array for the Arduino to step
through.

In the end, it really looked pretty good! Thing I consider to
be key points:
 * three light sources not synchronized
 * bright - each channel was a set of four 20 ma LEDs driven
   at 50 ma.
 * trigged both on and off by a push button switch in the pot
 * battery powered - I used a 6-cell AA battery holder
 * easy - more or less. *smiles* Between building and
   programming it the two of us spent probably less than 6 man
   hours.
 * contain in the pot, so it's fully portable.

--    Philip