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Sound, how is it done?

asked 2013-05-02 21:05:04 -0500

this post is marked as community wiki

This post is a wiki. Anyone with karma >750 is welcome to improve it.

Im working on an interactive piece using an alternate form of the doppler effect and I would appreciate some help in making it play sound. Thank you

import wave

class SoundFile:
   def  __init__(self, signal,lab=''):
       self.file = wave.open('./test' + lab + '.wav', 'wb')
       self.signal = signal
       self.sr = 44100

   def write(self):
       self.file.setparams((1, 2, self.sr, 44100*4, 'NONE', 'noncompressed'))
       self.file.writeframes(self.signal)
       self.file.close()

mypi = float(pi)
from math import sin
var('x')

@interact
def sinsound(f = slider(16,16000,1,5120)):
    v = 340.29
    html('$y = f*(((v)+ tan(x))/((v)+sin(x))))$')
    y = f*((v+tan(x))/(v+sin(x)))
    hz1 = y
    s2 = [sin(hz1*x*mypi*2) for x in srange(0,4,1/44100.0)]
    s2m = max(s2)
    s2f = [16384*x/s2m for x in s2]
    s2str = ''.join(wave.struct.pack('h',x) for x in s2f)
    lab="%1.2f"%float(f)
    f = SoundFile(s2str,lab=lab)
    f.write()
    pnum = 1500+int(500/f)
    show(list_plot(s2[0:pnum],plotjoined=True))
    html('<embed src="cell://test'+ lab +'.wav" width="200" height="100"></embed>')
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Comments

1

Hi. It is not clear at all what your code shoud do !! The variable **y** seems to be a function of **x** but is used as a float number. The parameter **f** has the same name as the **SoundFile** object... Anyway, as such because you use the function **sin** from **math** I get an error because you can not evaluate it on a symbolic variable.

vdelecroix gravatar imagevdelecroix ( 2013-05-04 11:29:36 -0500 )edit

You may also find the discussion [here](https://groups.google.com/forum/?fromgroups=#!topic/sage-devel/3-Y1RUFkq14) interesting, as well as [this ticket](http://trac.sagemath.org/sage_trac/ticket/7668).

kcrisman gravatar imagekcrisman ( 2013-05-07 15:46:50 -0500 )edit

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answered 2013-05-07 00:07:14 -0500

this post is marked as community wiki

This post is a wiki. Anyone with karma >750 is welcome to improve it.

Building on vdelecroix's comments, and slightly amending your code, the following works for me.

import wave

rdf_two_pi = RDF(2*pi)

class SoundFile:
   def  __init__(self,signal,lab=''):
       self.file = wave.open('./test' + lab + '.wav', 'wb')
       self.signal = signal
       self.sr = 44100
   def write(self):
       self.file.setparams((1, 2, self.sr, 44100*4, 'NONE', 'noncompressed'))
       self.file.writeframes(self.signal)
       self.file.close()

@interact
def sinsound(f=slider(16,16000,1,5120)):
    v = 340.29
    html(r'$$y = f \, \frac{v+\tan x}{v+\sin x}$$')
    def y(x):
        x = RDF(x)
        return f*((v+tan(x))/(v+sin(x)))
    s2 = [sin(y(t)*t*rdf_two_pi) for t in srange(0,4,1/44100.0)]
    s2m = max(s2)
    s2f = [int(16384*t/s2m) for t in s2]
    s2str = ''.join(wave.struct.pack('h',t) for t in s2f)
    lab="%1.2f"%float(f)
    sf = SoundFile(s2str,lab=lab)
    sf.write()
    pnum = 1500+int(500/f)
    show(list_plot(s2[0:pnum],plotjoined=True))
    html('<embed src="cell://test'+ lab +'.wav" width="200" height="100"></embed>')
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Asked: 2013-05-02 21:05:04 -0500

Seen: 367 times

Last updated: May 07 '13