audio-lab 0.1.0

Toolkit for audio research and testing
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96

use crate::signal::{TimeSignal, math::db_to_gain};

impl TimeSignal {
    pub fn energy_per_channel(&self) -> Vec<f64> {
        self.channel_iter()
            .map(|channel| channel.iter().map(|sample| sample * sample).sum())
            .collect()
    }

    pub fn power_per_channel(&self) -> Vec<f64> {
        let num_time_steps = self.num_time_steps();
        if num_time_steps == 0 {
            return vec![0.0; self.num_channels()];
        }

        self.energy_per_channel()
            .into_iter()
            .map(|energy| energy / num_time_steps as f64)
            .collect()
    }

    pub fn rms_per_channel(&self) -> Vec<f64> {
        self.power_per_channel()
            .into_iter()
            .map(f64::sqrt)
            .collect()
    }

    pub fn normalize_peak(&mut self, peak_level: f64) {
        let max = self.iter().map(|s| s.abs()).fold(0.0_f64, f64::max);
        if max == 0.0 {
            return;
        }
        let gain = peak_level / max;
        self.iter_mut().for_each(|s| *s *= gain);
    }

    pub fn normalize_peak_db(&mut self, peak_db: f64) {
        self.normalize_peak(db_to_gain(peak_db));
    }
}

#[cfg(test)]
mod tests {
    use approx::assert_abs_diff_eq;
    use ndarray::arr2;

    use crate::signal::TimeSignal;

    #[test]
    fn energy_power_and_rms_are_computed_per_channel() {
        let signal = TimeSignal::new(arr2(&[[1.0, -1.0, 2.0], [0.0, 3.0, 4.0]]), 48_000.0).unwrap();

        assert_eq!(signal.energy_per_channel().len(), 2);
        assert_abs_diff_eq!(signal.energy_per_channel()[0], 6.0, epsilon = 1e-12);
        assert_abs_diff_eq!(signal.energy_per_channel()[1], 25.0, epsilon = 1e-12);
        assert_abs_diff_eq!(signal.power_per_channel()[0], 2.0, epsilon = 1e-12);
        assert_abs_diff_eq!(signal.power_per_channel()[1], 25.0 / 3.0, epsilon = 1e-12);
        assert_abs_diff_eq!(signal.rms_per_channel()[0], 2.0_f64.sqrt(), epsilon = 1e-12);
        assert_abs_diff_eq!(
            signal.rms_per_channel()[1],
            (25.0_f64 / 3.0).sqrt(),
            epsilon = 1e-12
        );
    }

    #[test]
    fn power_and_rms_return_zero_for_empty_signals() {
        let signal = TimeSignal::zeros(2, 0, 48_000.0).unwrap();

        assert_eq!(signal.energy_per_channel(), vec![0.0, 0.0]);
        assert_eq!(signal.power_per_channel(), vec![0.0, 0.0]);
        assert_eq!(signal.rms_per_channel(), vec![0.0, 0.0]);
    }

    #[test]
    fn normalize_scales_to_requested_peak_linear() {
        let mut signal = TimeSignal::new(arr2(&[[0.25, -0.5, 1.0]]), 48_000.0).unwrap();
        signal.normalize_peak(0.5);

        assert_abs_diff_eq!(signal.channel(0)[0], 0.125, epsilon = 1e-12);
        assert_abs_diff_eq!(signal.channel(0)[1], -0.25, epsilon = 1e-12);
        assert_abs_diff_eq!(signal.channel(0)[2], 0.5, epsilon = 1e-12);
    }

    #[test]
    fn normalize_scales_to_requested_peak_db() {
        let mut signal = TimeSignal::new(arr2(&[[0.25, -0.5, 1.0]]), 48_000.0).unwrap();
        signal.normalize_peak_db(-6.0);

        let expected_peak = 10.0_f64.powf(-6.0 / 20.0);
        assert_abs_diff_eq!(signal.channel(0)[0], 0.25 * expected_peak, epsilon = 1e-12);
        assert_abs_diff_eq!(signal.channel(0)[1], -0.5 * expected_peak, epsilon = 1e-12);
        assert_abs_diff_eq!(signal.channel(0)[2], expected_peak, epsilon = 1e-12);
    }
}