1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
const SPS: u32 = 48_000;
const MAX_FREQ: f32 = 10_000.0;
const MIN_PERIOD: f32 = (SPS as f32) / MAX_FREQ;
struct ZeroCross(bool);
impl ZeroCross {
fn new() -> Self {
ZeroCross(false)
}
fn get(&mut self, s: f32, t: f32) -> bool {
if s < -t {
self.0 = false;
} else if s > t {
self.0 = true;
}
self.0
}
}
struct BitStream {
bits: Vec<usize>,
len: usize,
}
impl BitStream {
fn new(size: usize) -> BitStream {
let nbits = ::std::mem::size_of::<usize>() * 8;
BitStream {
bits: vec![0usize; size/nbits],
len: size,
}
}
fn set(&mut self, i: usize, value: bool) {
let nbits = ::std::mem::size_of::<usize>() * 8;
let index = i / nbits;
let bitofs = i % nbits;
self.bits[index] ^= (if value { ::std::usize::MAX } else { 0 }
^ self.bits[index]) & (1usize << bitofs);
}
fn autocorrelate(&mut self, start_pos: usize, f: &mut FnMut(usize, u32)) {
let nbits = ::std::mem::size_of::<usize>() * 8;
let mid_array = (self.bits.len() / 2) - 1;
let mid_pos = self.len / 2;
let mut index = start_pos / nbits;
let mut shift = start_pos % nbits;
for pos in start_pos..mid_pos {
let mut p1 = 0;
let mut p2 = index;
let mut count = 0;
if shift == 0 {
for _i in 0..mid_array {
count += (self.bits[p1] ^ self.bits[p2])
.count_ones();
p1+=1; p2+=1;
}
} else {
let shift2 = nbits - shift;
for _i in 0..mid_array {
let mut v = self.bits[p2] >> shift;
p2+=1;
v |= self.bits[p2] << shift2;
count += (self.bits[p1] ^ v).count_ones();
p1+=1;
}
}
shift += 1;
if shift == nbits {
shift = 0;
index += 1;
}
f(pos, count);
}
}
}
fn bcf(samples: &[f32]) -> Option<(f32, f32)> {
let mut volume = 0.0f32;
for i in samples.iter() {
volume = volume.max(i.abs());
}
let mut bin = BitStream::new(samples.len());
let mut zc = ZeroCross::new();
let t = volume * 0.00001;
for i in 0..samples.len() {
let setv = zc.get(samples[i], t);
bin.set(i, setv);
}
let mut max_count = 0u32;
let mut min_count = ::std::u32::MAX;
let mut est_index = 0usize;
let mut corr = vec![0u32; samples.len() / 2];
bin.autocorrelate(MIN_PERIOD as usize, &mut |pos, count| {
corr[pos] = count;
max_count = max_count.max(count);
if count < min_count {
min_count = count;
est_index = pos;
}
});
let mut prev = 0.0f32;
let mut start_edge = samples.iter().enumerate();
let start_edge = loop {
let (i, start_edge2) = start_edge.next()?;
if *start_edge2 > 0.0 {
break (i as f32, start_edge2);
}
prev = *start_edge2;
};
let mut dy = start_edge.1 - prev;
let dx1 = -prev / dy;
let mut next_edge = samples.iter().enumerate().skip(est_index - 1);
let next_edge = loop {
let (i, next_edge2) = next_edge.next()?;
if *next_edge2 > 0.0 {
break (i as f32, next_edge2);
}
prev = *next_edge2;
};
dy = next_edge.1 - prev;
let dx2 = -prev / dy;
let n_samples: f32 = (next_edge.0 - start_edge.0) + (dx2 - dx1);
println!("{} {} {} {} {}", n_samples, next_edge.0, start_edge.0, dx2, dx1);
Some(((SPS as f32) / n_samples, volume))
}
pub fn detect(samples: &[f32]) -> (f32, f32) {
bcf(samples).unwrap_or((0.0, 0.0))
}