go-resample

A pure-Go (no cgo) audio sample-rate converter.

• No cgo — cross-compiles and links cleanly into static Go binaries.
• Arbitrary & time-varying ratios in [1/256, 256] (ratio = output_rate / input_rate).
• Interleaved float32 frames, any channel count.

Converters

Converter	Quality	Cost	Notes
SincBestQuality	highest	high	widest passband, deepest stopband
SincMediumQuality	transparent for most uses	medium	good default
SincFastest	good	low	band-limited sinc, low CPU
ZeroOrderHold	low	trivial	nearest-sample hold
Linear	low	trivial	linear interpolation

The sinc converters build a Kaiser-windowed sinc prototype filter and evaluate it via a polyphase table with linear interpolation between phases; downsampling widens the filter for anti-aliasing and rescales for unity gain.

Usage

One-shot conversion of a whole buffer:

out, err := resample.Simple(in, 48000.0/44100.0, 2, resample.SincMediumQuality)

Streaming:

r, _ := resample.New(resample.SincMediumQuality, 2)
d := &resample.Data{
    In: in, InputFrames: len(in) / 2,
    Out: out, OutputFrames: len(out) / 2,
    Ratio: 2.0,
    EndOfInput: false, // set true on the final call
}
_ = r.Process(d)
// d.OutputFramesGen frames written; call again to feed more / drain.

License

BSD-2-Clause — see LICENSE. Credit for the reference implementation this work is based on is in NOTICE.