audio-processor-analysis 2.4.0

// Augmented Audio: Audio libraries and applications
// Copyright (c) 2022 Pedro Tacla Yamada
//
// The MIT License (MIT)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
use super::frame_deltas::DeltaFrames;

/// This is `F(frame, bin)` in the paper. Equation `5`.
///
/// This represents how much for each frame and each bin summed with `v`
/// neighbours has changed compared with previous and next frames.
pub struct PowerOfChangeFrames {
    pub buffer: Vec<Vec<f32>>,
}

impl PowerOfChangeFrames {
    pub fn len(&self) -> usize {
        self.buffer.len()
    }

    pub fn bins(&self) -> usize {
        if self.buffer.is_empty() {
            0
        } else {
            self.buffer[0].len()
        }
    }
}

pub struct PowerOfChangeParams {
    // This is `v` on the paper
    pub spectral_spread_bins: usize,
}

fn signal(f: f32) -> f32 {
    if f >= 0.0 {
        1.0
    } else {
        -1.0
    }
}

/// Calculates `F(frame, bin)`
pub fn calculate_power_of_change(
    params: PowerOfChangeParams,
    t_results: &DeltaFrames,
) -> PowerOfChangeFrames {
    // pre-allocate result
    let mut result = {
        let mut result = Vec::with_capacity(t_results.len());
        for _i in 0..t_results.len() {
            result.push({
                let mut v = Vec::with_capacity(t_results.bins());
                v.resize(t_results.bins(), 0.0);
                v
            });
        }
        result
    };

    let spectral_spread = params.spectral_spread_bins;

    for i in 0..t_results.len() {
        result.push({
            let mut v = Vec::with_capacity(t_results.bins());
            v.resize(t_results.bins(), 0.0);
            v
        });

        for j in 0..t_results.bins() {
            let mut sum = 0.0;
            let spectral_spread = spectral_spread as i32;

            {
                let j = j as i32;
                for k in j - spectral_spread..j + spectral_spread {
                    if k >= 0 && k < t_results.bins() as i32 {
                        let minus: f32 = t_results.minus[i][k as usize];
                        let plus: f32 = t_results.plus[i][k as usize];

                        sum += (1.0 + signal(minus)) * minus + (1.0 + signal(plus) * plus);
                    }
                }
            }

            result[i][j] = 0.5 * sum;
        }
    }

    PowerOfChangeFrames { buffer: result }
}