lewton/
samples.rs

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1// Vorbis decoder written in Rust
2//
3// Copyright (c) 2019 est31 <MTest31@outlook.com>
4// and contributors. All rights reserved.
5// Licensed under MIT license, or Apache 2 license,
6// at your option. Please see the LICENSE file
7// attached to this source distribution for details.
8
9/*!
10Traits for sample formats
11*/
12
13/// Trait for a packet of multiple samples
14pub trait Samples {
15	fn num_samples(&self) -> usize;
16	fn truncate(&mut self, limit :usize);
17	fn from_floats(floats :Vec<Vec<f32>>) -> Self;
18}
19
20impl<S :Sample> Samples for Vec<Vec<S>> {
21	fn num_samples(&self) -> usize {
22		self[0].len()
23	}
24	fn truncate(&mut self, limit :usize) {
25		for ch in self.iter_mut() {
26			if limit < ch.len() {
27				ch.truncate(limit);
28			}
29		}
30	}
31
32	fn from_floats(floats :Vec<Vec<f32>>) -> Self {
33		floats.into_iter()
34			.map(|samples| {
35				samples.into_iter()
36					.map(S::from_float)
37					.collect()
38			}).collect()
39	}
40}
41
42/// A packet of multi-channel interleaved samples
43pub struct InterleavedSamples<S :Sample> {
44	pub samples :Vec<S>,
45	pub channel_count :usize,
46}
47
48impl<S :Sample> Samples for InterleavedSamples<S> {
49	fn num_samples(&self) -> usize {
50		self.samples.len() / self.channel_count
51	}
52	fn truncate(&mut self, limit :usize) {
53		self.samples.truncate(limit * self.channel_count);
54	}
55	fn from_floats(floats :Vec<Vec<f32>>) -> Self {
56		let channel_count = floats.len();
57		// Note that a channel count of 0 is forbidden
58		// by the spec and the header decoding code already
59		// checks for that.
60		assert!(floats.len() > 0);
61		let samples_interleaved = if channel_count == 1 {
62			// Because decoded_pck[0] doesn't work...
63			<Vec<Vec<S>> as Samples>::from_floats(floats).into_iter().next().unwrap()
64		} else {
65			let len = floats[0].len();
66			let mut samples = Vec::with_capacity(len * channel_count);
67			for i in 0 .. len {
68				for ref chan in floats.iter() {
69					samples.push(S::from_float(chan[i]));
70				}
71			}
72			samples
73		};
74		Self {
75			samples : samples_interleaved,
76			channel_count,
77		}
78	}
79}
80
81/// Trait representing a single sample
82pub trait Sample {
83	fn from_float(fl :f32) -> Self;
84}
85
86impl Sample for f32 {
87	fn from_float(fl :f32) -> Self {
88		fl
89	}
90}
91
92impl Sample for i16 {
93	fn from_float(fl :f32) -> Self {
94		let fl = fl * 32768.0;
95		if fl > 32767. {
96			32767
97		} else if fl < -32768. {
98			-32768
99		} else {
100			fl as i16
101		}
102	}
103}
lewton/samples.rs

lewton/
samples.rs
