SignalSmith

Performs time-stretching and pitch-shifting on raw audio buffers using Signalsmith.

Description

SignalSmith is a low-level audio processing utility which wraps the Signalsmith time-stretching library. It operates on raw interleaved floating-point PCM audio buffers and allows independent control of playback tempo and pitch.

Methods

AudioStreamWAV	change_tempo(path: String, tempo: float, pitch: float = 1.0)
int	get_last_channels() const
int	get_last_sample_rate() const
PackedFloat32Array	process(input: PackedFloat32Array)
void	reset()
void	set_channels(channels: int)
void	set_pitch(pitch: float)
void	set_sample_rate(rate: int)
void	set_tempo(tempo: float)

Method Descriptions

AudioStreamWAV change_tempo(path: String, tempo: float, pitch: float = 1.0) 🔗

Loads an MP3 file, applies time-stretching and pitch-shifting using the Signalsmith engine, and returns a streamable AudioStreamWAV.

The tempo parameter controls playback speed without affecting pitch. A value of 1.0 preserves the original speed.

The pitch parameter is a transpose factor. A value of 1.0 preserves pitch, 2.0 raises pitch by one octave,

and 0.5 lowers pitch by one octave.

int get_last_channels() const 🔗

There is currently no description for this method. Please help us by contributing one!

int get_last_sample_rate() const 🔗

There is currently no description for this method. Please help us by contributing one!

PackedFloat32Array process(input: PackedFloat32Array) 🔗

Processes a block of interleaved audio samples and returns a new buffer containing the time-stretched and pitch-shifted result.

The effective playback speed is determined by the ratio of input samples to output samples, as influenced by the current tempo setting. The input buffer must contain 32-bit floating-point PCM data and be interleaved according to the configured channel count.

void reset() 🔗

Resets the internal processing state.

This should be called when restarting playback or discontinuously changing input streams.

void set_channels(channels: int) 🔗

Sets the number of audio channels.

Input and output buffers are expected to be interleaved according to this channel count.

void set_pitch(pitch: float) 🔗

Sets the pitch transpose factor.

A value of 1.0 leaves pitch unchanged. Values greater than 1.0 raise pitch, while values less than 1.0 lower pitch.

void set_sample_rate(rate: int) 🔗

Sets the sample rate, in Hz, used by the internal processing engine.

Changing the sample rate resets the internal state.

void set_tempo(tempo: float) 🔗

Sets the tempo multiplier used during processing.

This value influences the ratio between input and output buffer sizes during time-stretching. A value of 1.0 preserves the original tempo, values greater than 1.0 speed up playback, and values less than 1.0 slow it down.