geng_rodio/source/
fadein.rs

1use std::time::Duration;
2
3use crate::{Sample, Source};
4
5/// Internal function that builds a `FadeIn` object.
6pub fn fadein<I>(input: I, duration: Duration) -> FadeIn<I>
7where
8    I: Source,
9    I::Item: Sample,
10{
11    let duration = duration.as_secs() * 1000000000 + duration.subsec_nanos() as u64;
12
13    FadeIn {
14        input,
15        remaining_ns: duration as f32,
16        total_ns: duration as f32,
17    }
18}
19
20/// Filter that modifies raises the volume from silence over a time period.
21#[derive(Clone, Debug)]
22pub struct FadeIn<I> {
23    input: I,
24    remaining_ns: f32,
25    total_ns: f32,
26}
27
28impl<I> FadeIn<I>
29where
30    I: Source,
31    I::Item: Sample,
32{
33    /// Returns a reference to the inner source.
34    #[inline]
35    pub fn inner(&self) -> &I {
36        &self.input
37    }
38
39    /// Returns a mutable reference to the inner source.
40    #[inline]
41    pub fn inner_mut(&mut self) -> &mut I {
42        &mut self.input
43    }
44
45    /// Returns the inner source.
46    #[inline]
47    pub fn into_inner(self) -> I {
48        self.input
49    }
50}
51
52impl<I> Iterator for FadeIn<I>
53where
54    I: Source,
55    I::Item: Sample,
56{
57    type Item = I::Item;
58
59    #[inline]
60    fn next(&mut self) -> Option<I::Item> {
61        if self.remaining_ns <= 0.0 {
62            return self.input.next();
63        }
64
65        let factor = 1.0 - self.remaining_ns / self.total_ns;
66        self.remaining_ns -=
67            1000000000.0 / (self.input.sample_rate() as f32 * self.channels() as f32);
68        self.input.next().map(|value| value.amplify(factor))
69    }
70
71    #[inline]
72    fn size_hint(&self) -> (usize, Option<usize>) {
73        self.input.size_hint()
74    }
75}
76
77impl<I> ExactSizeIterator for FadeIn<I>
78where
79    I: Source + ExactSizeIterator,
80    I::Item: Sample,
81{
82}
83
84impl<I> Source for FadeIn<I>
85where
86    I: Source,
87    I::Item: Sample,
88{
89    #[inline]
90    fn current_frame_len(&self) -> Option<usize> {
91        self.input.current_frame_len()
92    }
93
94    #[inline]
95    fn channels(&self) -> u16 {
96        self.input.channels()
97    }
98
99    #[inline]
100    fn sample_rate(&self) -> u32 {
101        self.input.sample_rate()
102    }
103
104    #[inline]
105    fn total_duration(&self) -> Option<Duration> {
106        self.input.total_duration()
107    }
108}
geng_rodio/source/fadein.rs

geng_rodio/source/
fadein.rs
