5 Best Ways to Read and Write WAV Files Using Python Wave

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💡 Problem Formulation: In this article, we tackle the problem of how to effectively read from and write to WAV audio files using the Python wave module. This process could be fundamental in applications such as audio editing tools, data analysis within the sound domain, or software that requires audio file processing. The goal is to take a WAV audio file as input and showcase various methods to manipulate it using Python, with the desired output being an altered WAV file.

Method 1: Basic Reading and Writing

Python’s wave module is a straightforward option for dealing with WAV files. It provides functions to read in WAV files and retrieve their parameters, like frame rate and channels, as well as writing out new WAV files. This method is suitable for basic audio processing tasks.

Here’s an example:

import wave

# Open a WAV file for reading.
with wave.open('example.wav', 'rb') as wav_file:
    # Read audio frames and get parameters.
    audio_frames = wav_file.readframes(wav_file.getnframes())
    params = wav_file.getparams()

# Open a new WAV file for writing and set parameters.
with wave.open('output.wav', 'wb') as wav_file:
    wav_file.setparams(params)
    # Write audio frames to the new WAV file.
    wav_file.writeframes(audio_frames)

Output: A new WAV file named output.wav containing the data from example.wav.

This code snippet reads an existing WAV file named example.wav, extracts its audio frames and parameters such as sample width, number of frames, etc., and then writes this audio data to a new file named output.wav while preserving the original parameters.

Method 2: Frame-by-Frame Processing

Frame-by-frame processing allows you to manipulate the WAV file’s audio data frame by frame. This is helpful when you need to process or analyze the audio signal, apply filters, or if you’re going to modify the sound dynamically.

Here’s an example:

import wave

# Open original WAV file.
with wave.open('example.wav', 'rb') as original_wav:
    params = original_wav.getparams()
    # Create a new WAV file to write frames after processing.
    with wave.open('modified.wav', 'wb') as modified_wav:
        modified_wav.setparams(params)
        # Process and write frames one by one.
        for _ in range(params.nframes):
            frame = original_wav.readframes(1)
            # An example of frame processing (inverting the audio).
            modified_frame = bytes([255 - sample for sample in frame])
            modified_wav.writeframes(modified_frame)

Output: A new WAV file named modified.wav with the inverted audio of example.wav.

This code snippet reads an existing WAV file frame by frame, processes each frame by inverting the audio wave, and then writes each modified frame to a new file modified.wav. This method is more flexible when custom audio manipulation is needed.

Method 3: Extension for Large Files (Buffering)

When dealing with large WAV files, it’s advisable to use buffering to manage system memory. In this method, you read and write the audio data in chunks, which allows for consistent memory usage even with significant audio files.

Here’s an example:

import wave

buffer_size = 4096  # Define the buffer size.

# Open original WAV file.
with wave.open('large_example.wav', 'rb') as original_wav:
    params = original_wav.getparams()
    # Create a new WAV file for writing.
    with wave.open('large_output.wav', 'wb') as output_wav:
        output_wav.setparams(params)
        frames_remaining = params.nframes
        # Write in chunks using the buffer size.
        while frames_remaining > 0:
            buffer = original_wav.readframes(min(frames_remaining, buffer_size))
            output_wav.writeframes(buffer)
            frames_remaining -= buffer_size

Output: A new WAV file named large_output.wav containing the data from large_example.wav.

The buffer size defines how much data is read at once from the input file and written to the output file, allowing for efficient handling of large files without significant memory consumption.

Method 4: Adjusting Audio Parameters

wave module not only allows file reading and writing but also permits to change audio parameters like sample width or frame rate. Modifying these can drastically change the resulting audio, for example, reducing the frame rate to lower the pitch.

Here’s an example:

import wave

def change_frame_rate(input_wav, output_wav, new_frame_rate):
    with wave.open(input_wav, 'rb') as wav_r:
        params = list(wav_r.getparams())
        params[2] = new_frame_rate  # Change frame rate.
        frames = wav_r.readframes(params[3])

    with wave.open(output_wav, 'wb') as wav_w:
        wav_w.setparams(tuple(params))
        wav_w.writeframes(frames)

change_frame_rate('input.wav', 'changed_rate.wav', 16000)

Output: A new WAV file named changed_rate.wav that has a modified frame rate of 16000 Hz.

This function, change_frame_rate, reads an input file, modifies its frame rate parameter, and writes the audio frames to a new output file. This is useful for audio experiments or conversions.

Bonus One-Liner Method 5: Simple Copy

For the simplest form of reading and writing a WAV file without any modification, Python’s wave module can perform the operation in a virtually one-liner fashion utilizing file objects.

Here’s an example:

wave.open('copy_output.wav', 'wb').writeframes(wave.open('example.wav', 'rb').readframes())

Output: An exact copy of example.wav created as copy_output.wav.

This one-liner reads all frames from an input WAV file and directly writes them to a new output file, effectively copying the audio file in its entirety.

Summary/Discussion

  • Method 1: Basic reading and writing. Strengths: Simple and sufficient for basic tasks. Weaknesses: Limited in terms of more advanced audio processing needs.
  • Method 2: Frame-by-frame processing. Strengths: Offers more control for custom processing on each audio frame. Weaknesses: May be slower due to processing each frame individually.
  • Method 3: Extension for large files (buffering). Strengths: Efficient for memory management with large WAV files. Weaknesses: More complex than basic read/write operations.
  • Method 4: Adjusting audio parameters. Strengths: Flexibility to alter audio attributes like frame rate. Weaknesses: Requires knowledge of audio parameters and their impact.
  • Bonus One-Liner Method 5: Simple copy. Strengths: Quick copying of entire WAV files. Weaknesses: No scope for modification or processing.