Based on "Bandlimited interpolation" as described in https://ccrma.stanford.edu/~jos/resample/resample.pdf.

Features:

• Windowed-sinc FIR filter, supports both upsampling and downsampling by an arbitrary ratio.

• zlib-like API: Each call processes data until either input length or output length is exhausted. Each samples has to be provided only once (samples needed for overlap are stored internally).

• Written in C++11.

• TBD: Blackman vs. Kaiser window?

Usage:

  Resampler resam(1.5f); // upsample

  while (...more data...) {
    iused = resamp.process(out, olen, in, ilen);
    // olen returns "oused"
// or:
    resamp.process2(out, olen, in, ilen);
    // out, olen, in, ilen are all updated.
  }

TODO:

• Support fine-grained (relative) ratio adjustments with smooth update (set_relative_ratio()...)
• Expose current input -> output delay (useful for conversion between clock-domains via adaptive resampling, cf. https://kokkinizita.linuxaudio.org/papers/adapt-resamp.pdf).
• Multi-channel (planar? interleaved?)...
• Support setting fractional phase-shift with ratio = 1.0?

IDEAs:

• Allow double (currently: float) samples?

Copyright (c) 2024 Tobias Hoffmann

License: https://opensource.org/licenses/MIT