synthrs has the following function to convolve filters:

pub fn convolve(filter: &[f64], input: &[f64]) -> Vec<f64> {
    let mut output: Vec<f64> = Vec::new();
    let h_len = (filter.len() / 2) as isize;

    for i in -(filter.len() as isize / 2)..(input.len() as isize - 1) {
        output.push(0.0);
        for j in 0isize..filter.len() as isize {
            let input_idx = i + j;
            let output_idx = i + h_len;
            if input_idx < 0 || input_idx >= input.len() as isize {
                continue;
            }
            output[output_idx as usize] += input[input_idx as usize] * filter[j as usize]
        }
    }

    output
}

I'm trying to get my head around whether this can be adapted to take input as Iterator<Item = f64> and return Iterator<Item = f64>...