Crate rubato[][src]

An audio sample rate conversion library for Rust.

This library provides resamplers to process audio in chunks.

The ratio between input and output sample rates is completely free. Implementations are available that accept a fixed length input while returning a variable length output, and vice versa.

Asynchronous resampling

The resampling is based on band-limited interpolation using sinc interpolation filters. The sinc interpolation upsamples by an adjustable factor, and then the new sample points are calculated by interpolating between these points. The resampling ratio can be updated at any time.

Synchronous resampling

Synchronous resampling is implemented via FFT. The data is FFT:ed, the spectrum modified, and then inverse FFT:ed to get the resampled data. This type of resampler is considerably faster but doesn’t support changing the resampling ratio.

SIMD acceleration

The asynchronous resampler is designed to benefit from auto-vectorization, meaning that the Rust compiler can recognize calculations that can be done in parallel. It will then use SIMD instructions for those. This works quite well, but there is still room for improvement. On x86_64 it will always use SSE3 if available. The speed benefit compared to auto-vectorization depends on the CPU, but tends to be in the range 20-30% for 64-bit data, and 50-100% for 32-bit data.

Cargo features

avx: AVX on x86_64

The avx feature is enabled by default, and enables the use of AVX when it’s available. The speed increase compared to SSE depends on the CPU, and tends to range from zero to 50%. On other architectures than x86_64 the avx feature does nothing.

neon: Experimental Neon support on aarch64

Experimental support for Neon is available for aarch64 (64-bit Arm) by enabling the neon feature. This requires the use of a nightly compiler, as the Neon support in Rust is still experimental. On a Raspberry Pi 4, this gives a boost of about 10% for 64-bit floats and 50% for 32-bit floats when compared to the auto-vectorized implementation. Note that this only works on a full 64-bit operating system.


The full documentation can be generated by rustdoc. To generate and view it run:

cargo doc --open


Resample a single chunk of a dummy audio file from 44100 to 48000 Hz. See also the “fixedin64” example that can be used to process a file from disk.

use rubato::{Resampler, SincFixedIn, InterpolationType, InterpolationParameters, WindowFunction};
let params = InterpolationParameters {
    sinc_len: 256,
    f_cutoff: 0.95,
    interpolation: InterpolationType::Linear,
    oversampling_factor: 256,
    window: WindowFunction::BlackmanHarris2,
let mut resampler = SincFixedIn::<f64>::new(
    48000 as f64 / 44100 as f64,

let waves_in = vec![vec![0.0f64; 1024];2];
let waves_out = resampler.process(&waves_in).unwrap();


The rubato crate requires rustc version 1.40 or newer.





A synchronous resampler that needs a fixed number of audio frames for input and returns a variable number of frames.


A synchronous resampler that accepts a fixed number of audio frames for input and returns a fixed number of frames.


A synchronous resampler that needs a varying number of audio frames for input and returns a fixed number of frames.


A struct holding the parameters for interpolation.


Error raised when trying to use a CPU feature which is not supported.


A plain scalar interpolator


An asynchronous resampler that accepts a fixed number of audio frames for input and returns a variable number of frames.


An asynchronous resampler that return a fixed number of audio frames. The number of input frames required is given by the frames_needed function.



An identifier for a cpu feature.


Interpolation methods that can be selected. For asynchronous interpolation where the ratio between inut and output sample rates can be any number, it’s not possible to pre-calculate all the needed interpolation filters. Instead they have to be computed as needed, which becomes impractical since the sincs are very expensive to generate in terms of cpu time. It’s more efficient to combine the sinc filters with some other interpolation technique. Then sinc filters are used to provide a fixed number of interpolated points between input samples, and then the new value is calculated by interpolation between those points.


The error type used by rubato.


Different window functions that can be used to window the sinc function.



Dummy trait when not supported.


A resampler that us used to resample a chunk of audio to a new sample rate. The rate can be adjusted as required.


The trait governing a single sample.

Type Definitions


A result alias for the error type used by rubato.