lpc static method

Float32List lpc(Float32List input, { required int order, LpcMethod method = LpcMethod.levinson, })

Estimates LPC denominator coefficients a[0..order] from one frame.

The returned vector has length order + 1 and follows the convention a[0] = 1.

Methods:

• LpcMethod.levinson: autocorrelation + Levinson-Durbin.
• LpcMethod.burg: Burg's method (Marple-style recursion), aligned with librosa.lpc behavior for real-valued 1-D frames.

Implementation

static Float32List lpc(
  Float32List input, {
  required int order,
  LpcMethod method = LpcMethod.levinson,
}) {
  final L = input.length;
  final ctx = yl_lpc_ctx_create(order);
  if (ctx == ffi.nullptr) {
    throw StateError("Failed to create LPC context");
  }
  ffi.Pointer<ffi.Float> inPtr = ffi.nullptr;
  ffi.Pointer<ffi.Float> outPtr = ffi.nullptr;
  try {
    inPtr = calloc<ffi.Float>(L);
    outPtr = calloc<ffi.Float>(order + 1);
    inPtr.asTypedList(L).setAll(0, input);
    yl_lpc_ctx_process_frame(
      ctx,
      inPtr,
      L,
      method == LpcMethod.burg ? 1 : 0,
      0,
      outPtr,
    );

    final out = Float32List(order + 1);
    out.setAll(0, outPtr.asTypedList(order + 1));
    return out;
  } finally {
    if (inPtr != ffi.nullptr) calloc.free(inPtr);
    if (outPtr != ffi.nullptr) calloc.free(outPtr);
    yl_lpc_ctx_destroy(ctx);
  }
}