IO Guide

Every Signal has the methods play and export (only supports WAV). The latter has the positional argument filename, and both have the following keyword arguments:

• sample_rate - defaults to 44100. Valid values are 8000, 11025, 16000, 22050, 24000, 32000, 44100, 48000, 96000. Note that a Signal object doesn't know/care what sample rate it is supposed to be played in, even when it was directly loaded from a Wave file, so you will have to be explicit about sample rates other than 44.1 kHz.
• byte_width - defaults to 2 (16-bit). Supported values are 1,2,4 (TODO I think? there was something about floating points)
• max_amplitude - defaults to 1. This means that regardless of the actual volume of the audio, amplitudes will always be shrunk/stretched to fit between -1 and 1. This behaviour isn't really desired and can cause unexpected results, but we're not sure what's the best way to deal with it yet. However, specifying max_amplitude=None will keep all amplitudes exactly as they are.

Gensound signals are theoretical constructs that have no knowledge of the sample rate and byte width they are intended to have. Depending on whether we specify durations as milliseconds or number of samples, we may get very different results when exporting.

Changing sample rate of Raw audio

For a WAV or Raw Signal, use the resample method which recomputes the associated audio stream so it can be played using the desired sample rate without affecting pitch.

from gensound import WAV, test_wav

WAV(test_wav).play(sample_rate=32000) # will sound lower in pitch, since test_wav is in 44.1 kHz

WAV(test_wav).resample(32000).play(sample_rate=32000) # playback will now be at proper pitch

Or in order to save the file using the new sample rate:

WAV(test_wav).resample(32000).export("new_file.wav", sample_rate=32000)

Since WAV/Raw data is cached, calling resample once will affect all other objects contained the same WAV file. We may choose to implement an option to keep both the original as well as the resampled copies, but if that bothers you, you're most likely looking for the Stretch transform instead. Either way, one workaround is to load several unique copies of the original wave file, and another one is using Raw(WAV(filename).mixdown(original_sample_rate)) which effectively makes a unique copy in memory.

resample is a method of Raw, inherited by WAV. Note that it is not a Transform, for good reasons. If you thought about using it to stretch the audio while altering the pitch, you are probably looking for the Stretch transform, which works very much the same.