geng_rodio/
buffer.rs

1//! A simple source of samples coming from a buffer.
2//!
3//! The `SamplesBuffer` struct can be used to treat a list of values as a `Source`.
4//!
5//! # Example
6//!
7//! ```
8//! use rodio::buffer::SamplesBuffer;
9//! let _ = SamplesBuffer::new(1, 44100, vec![1i16, 2, 3, 4, 5, 6]);
10//! ```
11//!
12
13use std::time::Duration;
14use std::vec::IntoIter as VecIntoIter;
15
16use crate::{Sample, Source};
17
18/// A buffer of samples treated as a source.
19pub struct SamplesBuffer<S> {
20    data: VecIntoIter<S>,
21    channels: u16,
22    sample_rate: u32,
23    duration: Duration,
24}
25
26impl<S> SamplesBuffer<S>
27where
28    S: Sample,
29{
30    /// Builds a new `SamplesBuffer`.
31    ///
32    /// # Panic
33    ///
34    /// - Panics if the number of channels is zero.
35    /// - Panics if the samples rate is zero.
36    /// - Panics if the length of the buffer is larger than approximately 16 billion elements.
37    ///   This is because the calculation of the duration would overflow.
38    ///
39    pub fn new<D>(channels: u16, sample_rate: u32, data: D) -> SamplesBuffer<S>
40    where
41        D: Into<Vec<S>>,
42    {
43        assert!(channels != 0);
44        assert!(sample_rate != 0);
45
46        let data = data.into();
47        let duration_ns = 1_000_000_000u64.checked_mul(data.len() as u64).unwrap()
48            / sample_rate as u64
49            / channels as u64;
50        let duration = Duration::new(
51            duration_ns / 1_000_000_000,
52            (duration_ns % 1_000_000_000) as u32,
53        );
54
55        SamplesBuffer {
56            data: data.into_iter(),
57            channels,
58            sample_rate,
59            duration,
60        }
61    }
62}
63
64impl<S> Source for SamplesBuffer<S>
65where
66    S: Sample,
67{
68    #[inline]
69    fn current_frame_len(&self) -> Option<usize> {
70        None
71    }
72
73    #[inline]
74    fn channels(&self) -> u16 {
75        self.channels
76    }
77
78    #[inline]
79    fn sample_rate(&self) -> u32 {
80        self.sample_rate
81    }
82
83    #[inline]
84    fn total_duration(&self) -> Option<Duration> {
85        Some(self.duration)
86    }
87}
88
89impl<S> Iterator for SamplesBuffer<S>
90where
91    S: Sample,
92{
93    type Item = S;
94
95    #[inline]
96    fn next(&mut self) -> Option<S> {
97        self.data.next()
98    }
99
100    #[inline]
101    fn size_hint(&self) -> (usize, Option<usize>) {
102        self.data.size_hint()
103    }
104}
105
106#[cfg(test)]
107mod tests {
108    use crate::buffer::SamplesBuffer;
109    use crate::source::Source;
110
111    #[test]
112    fn basic() {
113        let _ = SamplesBuffer::new(1, 44100, vec![0i16, 0, 0, 0, 0, 0]);
114    }
115
116    #[test]
117    #[should_panic]
118    fn panic_if_zero_channels() {
119        SamplesBuffer::new(0, 44100, vec![0i16, 0, 0, 0, 0, 0]);
120    }
121
122    #[test]
123    #[should_panic]
124    fn panic_if_zero_sample_rate() {
125        SamplesBuffer::new(1, 0, vec![0i16, 0, 0, 0, 0, 0]);
126    }
127
128    #[test]
129    fn duration_basic() {
130        let buf = SamplesBuffer::new(2, 2, vec![0i16, 0, 0, 0, 0, 0]);
131        let dur = buf.total_duration().unwrap();
132        assert_eq!(dur.as_secs(), 1);
133        assert_eq!(dur.subsec_nanos(), 500_000_000);
134    }
135
136    #[test]
137    fn iteration() {
138        let mut buf = SamplesBuffer::new(1, 44100, vec![1i16, 2, 3, 4, 5, 6]);
139        assert_eq!(buf.next(), Some(1));
140        assert_eq!(buf.next(), Some(2));
141        assert_eq!(buf.next(), Some(3));
142        assert_eq!(buf.next(), Some(4));
143        assert_eq!(buf.next(), Some(5));
144        assert_eq!(buf.next(), Some(6));
145        assert_eq!(buf.next(), None);
146    }
147}
geng_rodio/buffer.rs

geng_rodio/
buffer.rs
