Function autocorr_fft 

pub fn autocorr_fft(
    buffer: &[f32],
    result: &mut [f32],
    scratch_buffer: &mut [f32],
    lag_count: usize,
)

Computes the autocorrelation of a given buffer using FFT.

Arguments

• buffer - Input buffer
• result - A buffer to write the result to.
• scratch_buffer - A scratch buffer used for temporary storage.
• lag_count - The length of the computed autocorrelation.