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Read and Write WAV Files Using Python Wave
The wave module in Python's standard library is an easy interface to the audio WAV format. The functions in this module can write audio data in raw format to a file like object and read the attributes of a WAV file.
The file is opened in 'write' or read mode just as with built-in open() function, but with open() function in wave module
wave.open()
This function opens a file to read/write audio data. The function needs two parameters - first the file name and second the mode. The mode can be 'wb' for writing audio data or 'rb' for reading.
obj = wave.open('sound.wav','wb')
A mode of 'rb' returns a Wave_read object, while a mode of 'wb' returns a Wave_write object.
Wave_write object has following methods
| close() | Close the file if it was opened by wave. |
| setnchannels() | Set the number of channels. 1 for Mono 2 for stereo channels |
| setsampwidth() | Set the sample width to n bytes. |
| setframerate() | Set the frame rate to n. |
| setnframes() | Set the number of frames to n. |
| setcomptype() | Set the compression type and description. At the moment, only compression type NONE is supported, meaning no compression. |
| setparams() | accepts parameter tuple (nchannels, sampwidth, framerate, nframes, comptype, compname) |
| tell() | Retrieves current position in the file |
| writeframesraw() | Write audio frames, without correcting. |
| writeframes() | Write audio frames and make sure they are correct. |
Following code creates a WAV file with random short integer bytes of 99999 seconds duration.
import wave, struct, math, random
sampleRate = 44100.0 # hertz
duration = 1.0 # seconds
frequency = 440.0 # hertz
obj = wave.open('sound.wav','w')
obj.setnchannels(1) # mono
obj.setsampwidth(2)
obj.setframerate(sampleRate)
for i in range(99999):
value = random.randint(-32767, 32767)
data = struct.pack('<h', value)
obj.writeframesraw( data )
obj.close()
Wave_read object methods
| close() | Close the stream if it was opened by wave module. |
| getnchannels() | Returns number of audio channels (1 for mono, 2 for stereo). |
| getsampwidth() | Returns sample width in bytes. |
| getframerate() | Returns sampling frequency. |
| getnframes() | Returns number of audio frames. |
| getcomptype() | Returns compression type ('NONE' is the only supported type). |
| getparams() | Returns a namedtuple() (nchannels, sampwidth, framerate, nframes, comptype, compname), equivalent to output of the get*() methods. |
| readframes(n) | Reads and returns at most n frames of audio, as a bytes object. |
| rewind() | Rewind the file pointer to the beginning of the audio stream. |
Following code reads some of the parameters of WAV file.
import wave
obj = wave.open('sound.wav','r')
print( "Number of channels",obj.getnchannels())
print ( "Sample width",obj.getsampwidth())
print ( "Frame rate.",obj.getframerate())
print ("Number of frames",obj.getnframes())
print ( "parameters:",obj.getparams())
obj.close()
Output
Number of channels 1 Sample width 2 Frame rate. 44100 Number of frames 99999 parameters: _wave_params(nchannels=1, sampwidth=2, framerate=44100, nframes=99999, comptype='NONE', compname='not compressed')
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