diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/transforms.rs | 45 |
1 files changed, 43 insertions, 2 deletions
diff --git a/src/transforms.rs b/src/transforms.rs index d56bc4c..7bcdf7c 100644 --- a/src/transforms.rs +++ b/src/transforms.rs @@ -81,7 +81,43 @@ pub fn find_fundamental_frequency_correlation(input: &Vec<f64>, sample_rate: f64 .fold((first_peak_width, 0.0 as f64), |(xi, xmag), (yi, &ymag)| if ymag > xmag { (yi, ymag) } else { (xi, xmag) }); let (peak_index, _) = peak; - Some(sample_rate / peak_index as f64) + + let refined_peak_index = refine_fundamentals(&correlation, peak_index as f64); + + Some(sample_rate / refined_peak_index) +} + +fn refine_fundamentals(correlation: &Vec<f64>, initial_guess: f64) -> f64 { + let mut low_bound = initial_guess - 0.5; + let mut high_bound = initial_guess + 0.5; + + for _ in 0..5 { + let data_points = 2 * correlation.len() / high_bound.ceil() as usize; + let low_guess = score_guess(&correlation, low_bound, data_points); + let high_guess = score_guess(&correlation, high_bound, data_points); + + let midpoint = (low_bound + high_bound) / 2.0; + if high_guess > low_guess { + low_bound = midpoint; + } + else { + high_bound = midpoint; + } + } + (low_bound + high_bound) / 2.0 +} + +fn score_guess(correlation: &Vec<f64>, period: f64, data_points: usize) -> f64 { + let mut score = 0.0; + for i in 0..data_points { + if i % 2 == 0 { + score += i as f64 * interpolate(&correlation, i as f64 * period / 2.0); + } + else { + score -= i as f64 * interpolate(&correlation, i as f64 * period / 2.0); + } + } + score } fn interpolate(correlation: &Vec<f64>, x: f64) -> f64 { @@ -99,7 +135,12 @@ fn interpolate(correlation: &Vec<f64>, x: f64) -> f64 { let x1 = x.ceil(); let y1 = correlation[x1 as usize]; - (y0*(x1-x) + y1*(x-x0)) / (x1-x0) + if (x0 as usize == x1 as usize) { + y0 + } + else { + (y0*(x1-x) + y1*(x-x0)) / (x1-x0) + } } } |