Convert list of floats into buffer in Python?
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22-07-2019 - |
Question
I am playing around with PortAudio and Python.
data = getData()
stream.write( data )
I want my stream to play sound data, that is represented in Float32 values. Therefore I use the following function:
def getData():
data = []
for i in range( 0, 1024 ):
data.append( 0.25 * math.sin( math.radians( i ) ) )
return data
Unfortunately that doesn't work because stream.write
wants a buffer object to be passed in:
TypeError: argument 2 must be string or read-only buffer, not list
So my question is: How can I convert my list of floats in to a buffer object?
Solution
import struct
def getData():
data = []
for i in range( 0, 1024 ):
data.append( 0.25 * math.sin( math.radians( i ) ) )
return struct.pack('f'*len(data), *data)
OTHER TIPS
Actually, the easiest way is to use the struct module. It is designed to convert from python objects to C-like "native" objects.
Consider perhaps instead:
d = [0.25 * math.sin(math.radians(i)) for i in range(0, 1024)]
Perhaps you have to use a package like pickle to serialize the data first.
import pickle
f1 = open("test.dat", "wb")
pickle.dump(d, f1)
f1.close()
Then load it back in:
f2 = open("test.dat", "rb")
d2 = pickle.Unpickler(f2).load()
f2.close()
d2 == d
Returns True
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