Python Wave File Fun and Audio on Arduino

I had never touched the struct library before. I believe it is the main way to use python to interact with bit formats.

https://docs.python.org/2/library/struct.html

Strings are byty things, so I guess struct uses them as a bridge between pythons weirdo types and the bare metal of c types. I think something similar can be done using numpy.

16 bit wave is signed integers, 8bit is unsigned. That goofed me off. I never got the resaved file to sound not alike a demon though, so there is something wrong in the code. The outputted c file worked like a charm, so I guess who cares. That’s all I wanted anyhow, I was just rewriting the wave for debugging.

import wave
import struct

myaudio = wave.open('test.wav', 'r')


newaudio = wave.open('new.wav', 'w')
newaudio.setparams((1, 1, myaudio.getframerate(), 0, 'NONE', 'not compressed'))

f = open('music.c', 'w')

f.write('const byte audio[] PROGMEM= {')

f.write(str(myaudio.getnframes() >> 8 + 128))
for i in range( myaudio.getnframes()-1):
#for i in range(100):
    f.write(',')
    waveData = myaudio.readframes(1)
    data = struct.unpack("h", waveData)
    val = ( int(data[0])>> 8) + 128

    f.write(str( val ))
    packed_value = struct.pack('B', val) #unsigned char is 1 byte

    newaudio.writeframes(packed_value)


print mymax
print mymin
f.write('};\n')
myaudio.close()
newaudio.close()
f.close()

Tried using an R-2R ladder to make a ADC for the arduino. It worked, we buffered the output with a simple emitter follower circuit.

Way overkill though.

I was thinking of using the analog in in some kind of feedback loop with a capacitor as an ADC when I found this.

http://highlowtech.org/?p=1963

This does the same thing with no parts (well, still need a buffer to get full volume). Clev. Majorly clev.

A speaker can’t respond at ~60kHz (nor would you hear it) so the fact that there is a pwm and not a true ADC going does not matter. Noice.

 

Incidentally, installed crayon for wordpress. Code looks way freaking better.

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