audio_visualizer/waveform/
plotters_png_file.rs

1/*
2MIT License
3
4Copyright (c) 2021 Philipp Schuster
5
6Permission is hereby granted, free of charge, to any person obtaining a copy
7of this software and associated documentation files (the "Software"), to deal
8in the Software without restriction, including without limitation the rights
9to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10copies of the Software, and to permit persons to whom the Software is
11furnished to do so, subject to the following conditions:
12
13The above copyright notice and this permission notice shall be included in all
14copies or substantial portions of the Software.
15
16THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22SOFTWARE.
23*/
24//! Static waveform visualization which exports the waveform to a PNG file.
25
26use crate::Channels;
27use plotters::prelude::*;
28use std::path::PathBuf;
29
30/// Visualizes audio as a waveform in a png file using "plotters" crate.
31/// If the data is stereo, it creates two files (with "left_" and "right_" prefix).
32pub fn waveform_static_plotters_png_visualize(
33    samples: &[i16],
34    channels: Channels,
35    directory: &str,
36    filename: &str,
37) {
38    if channels.is_stereo() {
39        assert_eq!(
40            0,
41            samples.len() % 2,
42            "If stereo is provided, the length of the audio data must be even!"
43        );
44        let (left, right) = channels.stereo_interleavement().to_channel_data(samples);
45        waveform_static_plotters_png_visualize(
46            &left,
47            Channels::Mono,
48            directory,
49            &format!("left_{}", filename),
50        );
51        waveform_static_plotters_png_visualize(
52            &right,
53            Channels::Mono,
54            directory,
55            &format!("right_{}", filename),
56        );
57        return;
58    }
59
60    let mut path = PathBuf::new();
61    path.push(directory);
62    path.push(filename);
63
64    let mut max = 0;
65    for sample in samples {
66        let sample = *sample as i32;
67        let sample = sample.abs();
68        if sample > max {
69            max = sample;
70        }
71    }
72
73    let width = (samples.len() / 5) as u32;
74    let width = if width > 4000 { 4000 } else { width };
75    let root = BitMapBackend::new(&path, (width, 1000)).into_drawing_area();
76    root.fill(&WHITE).unwrap();
77    let mut chart = ChartBuilder::on(&root)
78        .caption("y=music(t)", ("sans-serif", 50).into_font())
79        .margin(5)
80        .x_label_area_size(30)
81        .y_label_area_size(30)
82        .build_cartesian_2d(0.0..samples.len() as f32, -max as f32..max as f32)
83        .unwrap();
84
85    chart.configure_mesh().draw().unwrap();
86
87    chart
88        .draw_series(LineSeries::new(
89            // (-50..=50).map(|x| x as f32 / 50.0).map(|x| (x, x * x)),
90            samples
91                .iter()
92                .enumerate()
93                .map(|(sample_i, amplitude)| (sample_i as f32, *amplitude as f32)),
94            &RED,
95        ))
96        .unwrap()
97        // .label("y = music(t)")
98        .legend(|(x, y)| PathElement::new(vec![(x, y), (x + 20, y)], RED));
99
100    chart
101        .configure_series_labels()
102        .background_style(WHITE.mix(0.8))
103        .border_style(BLACK)
104        .draw()
105        .unwrap();
106}
107
108#[cfg(test)]
109mod tests {
110    use super::*;
111    use crate::tests::testutil::{TEST_OUT_DIR, TEST_SAMPLES_DIR};
112    use crate::ChannelInterleavement;
113    use minimp3::{Decoder as Mp3Decoder, Error as Mp3Error, Frame as Mp3Frame};
114    use std::fs::File;
115
116    #[test]
117    fn test_visualize_png_output() {
118        let mut path = PathBuf::new();
119        path.push(TEST_SAMPLES_DIR);
120        path.push("sample_1.mp3");
121        let mut decoder = Mp3Decoder::new(File::open(path).unwrap());
122
123        let mut lrlr_mp3_samples = vec![];
124        loop {
125            match decoder.next_frame() {
126                Ok(Mp3Frame {
127                    data: samples_of_frame,
128                    ..
129                }) => {
130                    for sample in samples_of_frame {
131                        lrlr_mp3_samples.push(sample);
132                    }
133                }
134                Err(Mp3Error::Eof) => break,
135                Err(e) => panic!("{:?}", e),
136            }
137        }
138
139        waveform_static_plotters_png_visualize(
140            &lrlr_mp3_samples,
141            Channels::Stereo(ChannelInterleavement::LRLR),
142            TEST_OUT_DIR,
143            "waveform_static_plotters_png_visualize_example.png",
144        );
145    }
146}
audio_visualizer/waveform/plotters_png_file.rs

audio_visualizer/waveform/
plotters_png_file.rs
