diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/gui.rs | 5 | ||||
| -rw-r--r-- | src/transforms.rs | 79 |
2 files changed, 71 insertions, 13 deletions
@@ -112,9 +112,10 @@ fn connect_dropdown_choose_microphone(mic_sender: Sender<Vec<f64>>, state: Rc<Re fn start_processing_audio(mic_receiver: Receiver<Vec<f64>>, pitch_sender: Sender<String>, freq_sender: Sender<Vec<::transforms::FrequencyBucket>>) { thread::spawn(move || { for samples in mic_receiver { - let frequency_domain = ::transforms::fft(samples, 44100.0); + let frequency_domain = ::transforms::fft(&samples, 44100.0); freq_sender.send(frequency_domain.clone()).ok(); - let fundamental = ::transforms::find_fundamental_frequency(&frequency_domain); + + let fundamental = ::transforms::find_fundamental_frequency_correlation(&samples, 44100.0); let pitch = match fundamental { Some(fundamental) => ::transforms::hz_to_pitch(fundamental), None => "".to_string() diff --git a/src/transforms.rs b/src/transforms.rs index 82966a9..d84692f 100644 --- a/src/transforms.rs +++ b/src/transforms.rs @@ -13,7 +13,7 @@ impl FrequencyBucket { } } -pub fn fft(input: Vec<f64>, sample_rate: f64) -> Vec<FrequencyBucket> { +pub fn fft(input: &Vec<f64>, sample_rate: f64) -> Vec<FrequencyBucket> { let frames = input.len(); let mean_input = input.iter().sum::<f64>()/input.len() as f64; @@ -48,6 +48,35 @@ pub fn find_fundamental_frequency(frequency_domain: &Vec<FrequencyBucket>) -> Op Some(max_bucket.ave_freq()) } +pub fn find_fundamental_frequency_correlation(input: &Vec<f64>, sample_rate: f64) -> Option<f64> { + let mut correlation = Vec::with_capacity(input.len()); + for offset in 0..input.len() { + let mut c = 0.0; + for i in 0..input.len()-offset { + let j = i+offset; + c += input[i] * input[j]; + } + correlation.push(c); + } + + //at offset = 0, we have union, so we want to remove that peak + for offset in 1..correlation.len() { + if correlation[offset-1] < correlation[offset] { + break; + } + correlation[offset-1] = 0.0; + } + + let peak = correlation.iter() + .enumerate() + .fold((0, 0.0 as f64), |(xi, xmag), (yi, &ymag)| if ymag > xmag { (yi, ymag) } else { (xi, xmag) }); + + let (peak_index, _) = peak; + + let peak_period = peak_index as f64 / sample_rate; + Some(peak_period.recip()) +} + #[cfg(test)] mod tests { use super::*; @@ -74,10 +103,10 @@ mod tests { #[test] fn fft_on_sine_wave() { - let frequency = 10000.0 as f64; //10KHz + let frequency = 440.0 as f64; //concert A let samples = sample_sinusoud(1.0, frequency, 0.0); - let frequency_domain = fft(samples, SAMPLE_RATE); + let frequency_domain = fft(&samples, SAMPLE_RATE); let fundamental = find_fundamental_frequency(&frequency_domain).unwrap(); assert!((fundamental-frequency).abs() < frequency_resolution(), "expected={}, actual={}", frequency, fundamental); @@ -86,19 +115,44 @@ mod tests { #[test] fn fft_on_two_sine_waves() { //Unfortunately, real signals won't be this neat - let samples1k = sample_sinusoud(2.0, 1000.0, 0.0); - let samples2k = sample_sinusoud(1.0, 10000.0, 0.0); - let expected_fundamental = 1000.0; + let samples1a = sample_sinusoud(2.0, 440.0, 0.0); + let samples2a = sample_sinusoud(1.0, 880.0, 0.0); + let expected_fundamental = 440.0; - let samples = samples1k.iter().zip(samples2k.iter()) + let samples = samples1a.iter().zip(samples2a.iter()) .map(|(a, b)| a+b) .collect(); - let frequency_domain = fft(samples, SAMPLE_RATE); + let frequency_domain = fft(&samples, SAMPLE_RATE); let fundamental = find_fundamental_frequency(&frequency_domain).unwrap(); assert!((fundamental-expected_fundamental).abs() < frequency_resolution(), "expected_fundamental={}, actual={}", expected_fundamental, fundamental); } + + #[test] + fn correlation_on_sine_wave() { + let frequency = 440.0 as f64; //concert A + + let samples = sample_sinusoud(1.0, frequency, 0.0); + let fundamental = find_fundamental_frequency_correlation(&samples, SAMPLE_RATE).unwrap(); + assert!((fundamental-frequency).abs() < frequency_resolution(), "expected={}, actual={}", frequency, fundamental); + } + + #[test] + fn correlation_on_two_sine_waves() { + //Unfortunately, real signals won't be this neat + let samples1a = sample_sinusoud(2.0, 440.0, 0.0); + let samples2a = sample_sinusoud(1.0, 880.0, 0.0); + let expected_fundamental = 440.0; + + let samples = samples1a.iter().zip(samples2a.iter()) + .map(|(a, b)| a+b) + .collect(); + + let fundamental = find_fundamental_frequency_correlation(&samples, SAMPLE_RATE).unwrap(); + + assert!((fundamental-expected_fundamental).abs() < frequency_resolution(), "expected_fundamental={}, actual={}", expected_fundamental, fundamental); + } } pub fn hz_to_pitch(hz: f64) -> String { @@ -120,9 +174,12 @@ pub fn hz_to_pitch(hz: f64) -> String { let midi_number = 69.0 + 12.0 * (hz / 440.0).log2(); //midi_number of 0 is C-1. - let rounded_pitch = midi_number.round() as usize; - let name = pitch_names[rounded_pitch%pitch_names.len()].to_string(); - let octave = rounded_pitch / pitch_names.len() - 1; //0 is C-1 + let rounded_pitch = midi_number.round() as i32; + let name = pitch_names[rounded_pitch as usize % pitch_names.len()].to_string(); + let octave = rounded_pitch / pitch_names.len() as i32 - 1; //0 is C-1 + if octave < 0 { + return "< C1".to_string(); + } let mut cents = ((midi_number * 100.0).round() % 100.0) as i32; if cents >= 50 { |