rodio/source/
position.rs

1use std::time::Duration;
2
3use super::SeekError;
4use crate::common::{ChannelCount, SampleRate};
5use crate::math::nz;
6use crate::Source;
7
8/// Internal function that builds a `TrackPosition` object. See trait docs for
9/// details
10pub fn track_position<I>(source: I) -> TrackPosition<I> {
11    TrackPosition {
12        input: source,
13        samples_counted: 0,
14        offset_duration: 0.0,
15        current_span_sample_rate: nz!(1),
16        current_span_channels: nz!(1),
17        current_span_len: None,
18    }
19}
20
21/// Tracks the elapsed duration since the start of the underlying source.
22#[derive(Debug)]
23pub struct TrackPosition<I> {
24    input: I,
25    samples_counted: usize,
26    offset_duration: f64,
27    current_span_sample_rate: SampleRate,
28    current_span_channels: ChannelCount,
29    current_span_len: Option<usize>,
30}
31
32impl<I> TrackPosition<I> {
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> TrackPosition<I>
53where
54    I: Source,
55{
56    /// Returns the position of the underlying source relative to its start.
57    ///
58    /// If a speedup and or delay is applied after applying a
59    /// [`Source::track_position`] it will not be reflected in the position
60    /// returned by [`get_pos`](TrackPosition::get_pos).
61    ///
62    /// This can get confusing when using [`get_pos()`](TrackPosition::get_pos)
63    /// together with [`Source::try_seek()`] as the the latter does take all
64    /// speedup's and delay's into account. Its recommended therefore to apply
65    /// track_position after speedup's and delay's.
66    #[inline]
67    pub fn get_pos(&self) -> Duration {
68        let seconds = self.samples_counted as f64
69            / self.input.sample_rate().get() as f64
70            / self.input.channels().get() as f64
71            + self.offset_duration;
72        Duration::from_secs_f64(seconds)
73    }
74
75    #[inline]
76    fn set_current_span(&mut self) {
77        self.current_span_len = self.current_span_len();
78        self.current_span_sample_rate = self.sample_rate();
79        self.current_span_channels = self.channels();
80    }
81}
82
83impl<I> Iterator for TrackPosition<I>
84where
85    I: Source,
86{
87    type Item = I::Item;
88
89    #[inline]
90    fn next(&mut self) -> Option<I::Item> {
91        // This should only be executed once at the first call to next.
92        if self.current_span_len.is_none() {
93            self.set_current_span();
94        }
95
96        let item = self.input.next();
97        if item.is_some() {
98            self.samples_counted += 1;
99
100            // At the end of a span add the duration of this span to
101            // offset_duration and start collecting samples again.
102            if Some(self.samples_counted) == self.current_span_len() {
103                self.offset_duration += self.samples_counted as f64
104                    / self.current_span_sample_rate.get() as f64
105                    / self.current_span_channels.get() as f64;
106
107                // Reset.
108                self.samples_counted = 0;
109                self.set_current_span();
110            };
111        };
112        item
113    }
114
115    #[inline]
116    fn size_hint(&self) -> (usize, Option<usize>) {
117        self.input.size_hint()
118    }
119}
120
121impl<I> Source for TrackPosition<I>
122where
123    I: Source,
124{
125    #[inline]
126    fn current_span_len(&self) -> Option<usize> {
127        self.input.current_span_len()
128    }
129
130    #[inline]
131    fn channels(&self) -> ChannelCount {
132        self.input.channels()
133    }
134
135    #[inline]
136    fn sample_rate(&self) -> SampleRate {
137        self.input.sample_rate()
138    }
139
140    #[inline]
141    fn total_duration(&self) -> Option<Duration> {
142        self.input.total_duration()
143    }
144
145    #[inline]
146    fn try_seek(&mut self, pos: Duration) -> Result<(), SeekError> {
147        let result = self.input.try_seek(pos);
148        if result.is_ok() {
149            self.offset_duration = pos.as_secs_f64();
150            // This assumes that the seek implementation of the codec always
151            // starts again at the beginning of a span. Which is the case with
152            // symphonia.
153            self.samples_counted = 0;
154        }
155        result
156    }
157}
158
159#[cfg(test)]
160mod tests {
161    use std::time::Duration;
162
163    use crate::buffer::SamplesBuffer;
164    use crate::math::nz;
165    use crate::source::Source;
166
167    #[test]
168    fn test_position() {
169        let inner = SamplesBuffer::new(nz!(1), nz!(1), vec![10.0, -10.0, 10.0, -10.0, 20.0, -20.0]);
170        let mut source = inner.track_position();
171
172        assert_eq!(source.get_pos().as_secs_f32(), 0.0);
173        source.next();
174        assert_eq!(source.get_pos().as_secs_f32(), 1.0);
175
176        source.next();
177        assert_eq!(source.get_pos().as_secs_f32(), 2.0);
178
179        assert!(source.try_seek(Duration::new(1, 0)).is_ok());
180        assert_eq!(source.get_pos().as_secs_f32(), 1.0);
181    }
182
183    #[test]
184    fn test_position_in_presence_of_speedup() {
185        let inner = SamplesBuffer::new(nz!(1), nz!(1), vec![10.0, -10.0, 10.0, -10.0, 20.0, -20.0]);
186        let mut source = inner.speed(2.0).track_position();
187
188        assert_eq!(source.get_pos().as_secs_f32(), 0.0);
189        source.next();
190        assert_eq!(source.get_pos().as_secs_f32(), 0.5);
191
192        source.next();
193        assert_eq!(source.get_pos().as_secs_f32(), 1.0);
194
195        assert!(source.try_seek(Duration::new(1, 0)).is_ok());
196        assert_eq!(source.get_pos().as_secs_f32(), 1.0);
197    }
198}
rodio/source/position.rs

rodio/source/
position.rs
