av-drift-detector 0.6.1

Generate machine-readable A/V sync test videos and measure audio/video drift frame by frame
Documentation 
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
201
202
203
204
205
206
207
208
209
210

//! A small 7-pixel-high bitmap font for the info line and the project's link:
//! digits, the lower-case letters, `A` and `H`, `×`, `·`, `.`, `:`, `/`, `-`
//! and space. Lower-case letters sit on a five-pixel x-height; descenders are
//! tucked in (`g`, `p`, `y`). Each font pixel is drawn as a `scale`×`scale` square.

use super::canvas::{LumaCanvas, Rect};

/// Rows of font pixels in a glyph.
pub const ROWS: i32 = 7;

/// A glyph's width in font pixels and its rows, top first. Bit `width - 1` is
/// the leftmost pixel.
type Glyph = (u8, [u8; ROWS as usize]);

fn glyph(ch: char) -> Option<Glyph> {
    Some(match ch {
        '0' => (
            5,
            [
                0b01110, 0b10001, 0b10011, 0b10101, 0b11001, 0b10001, 0b01110,
            ],
        ),
        '1' => (
            5,
            [
                0b00100, 0b01100, 0b00100, 0b00100, 0b00100, 0b00100, 0b01110,
            ],
        ),
        '2' => (
            5,
            [
                0b01110, 0b10001, 0b00001, 0b00010, 0b00100, 0b01000, 0b11111,
            ],
        ),
        '3' => (
            5,
            [
                0b11111, 0b00010, 0b00100, 0b00010, 0b00001, 0b10001, 0b01110,
            ],
        ),
        '4' => (
            5,
            [
                0b00010, 0b00110, 0b01010, 0b10010, 0b11111, 0b00010, 0b00010,
            ],
        ),
        '5' => (
            5,
            [
                0b11111, 0b10000, 0b11110, 0b00001, 0b00001, 0b10001, 0b01110,
            ],
        ),
        '6' => (
            5,
            [
                0b00110, 0b01000, 0b10000, 0b11110, 0b10001, 0b10001, 0b01110,
            ],
        ),
        '7' => (
            5,
            [
                0b11111, 0b00001, 0b00010, 0b00100, 0b01000, 0b01000, 0b01000,
            ],
        ),
        '8' => (
            5,
            [
                0b01110, 0b10001, 0b10001, 0b01110, 0b10001, 0b10001, 0b01110,
            ],
        ),
        '9' => (
            5,
            [
                0b01110, 0b10001, 0b10001, 0b01111, 0b00001, 0b00010, 0b01100,
            ],
        ),
        '×' => (5, [0, 0b10001, 0b01010, 0b00100, 0b01010, 0b10001, 0]),
        '·' => (3, [0, 0, 0, 0b010, 0, 0, 0]),
        '.' => (2, [0, 0, 0, 0, 0, 0b11, 0b11]),
        ':' => (2, [0, 0b11, 0b11, 0, 0b11, 0b11, 0]),
        '/' => (
            5,
            [
                0b00001, 0b00010, 0b00010, 0b00100, 0b01000, 0b01000, 0b10000,
            ],
        ),
        '-' => (4, [0, 0, 0, 0, 0b1111, 0, 0]),
        'A' => (
            5,
            [
                0b01110, 0b10001, 0b10001, 0b11111, 0b10001, 0b10001, 0b10001,
            ],
        ),
        'H' => (
            5,
            [
                0b10001, 0b10001, 0b10001, 0b11111, 0b10001, 0b10001, 0b10001,
            ],
        ),
        'a' => (4, [0, 0, 0b0110, 0b0001, 0b0111, 0b1001, 0b0111]),
        'b' => (4, [0b1000, 0b1000, 0b1110, 0b1001, 0b1001, 0b1001, 0b1110]),
        'c' => (4, [0, 0, 0b0111, 0b1000, 0b1000, 0b1000, 0b0111]),
        'd' => (4, [0b0001, 0b0001, 0b0111, 0b1001, 0b1001, 0b1001, 0b0111]),
        'e' => (4, [0, 0, 0b0110, 0b1001, 0b1111, 0b1000, 0b0111]),
        'f' => (4, [0b0011, 0b0100, 0b1111, 0b0100, 0b0100, 0b0100, 0b0100]),
        'g' => (4, [0, 0, 0b0111, 0b1001, 0b0111, 0b0001, 0b0110]),
        'h' => (4, [0b1000, 0b1000, 0b1110, 0b1001, 0b1001, 0b1001, 0b1001]),
        'i' => (3, [0b010, 0, 0b110, 0b010, 0b010, 0b010, 0b111]),
        'j' => (3, [0b001, 0, 0b011, 0b001, 0b001, 0b101, 0b010]),
        'k' => (4, [0b1000, 0b1000, 0b1001, 0b1010, 0b1100, 0b1010, 0b1001]),
        'l' => (3, [0b110, 0b010, 0b010, 0b010, 0b010, 0b010, 0b111]),
        'm' => (5, [0, 0, 0b11010, 0b10101, 0b10101, 0b10101, 0b10101]),
        'n' => (4, [0, 0, 0b1110, 0b1001, 0b1001, 0b1001, 0b1001]),
        'o' => (4, [0, 0, 0b0110, 0b1001, 0b1001, 0b1001, 0b0110]),
        'p' => (4, [0, 0, 0b1110, 0b1001, 0b1110, 0b1000, 0b1000]),
        'q' => (4, [0, 0, 0b0111, 0b1001, 0b0111, 0b0001, 0b0001]),
        'r' => (4, [0, 0, 0b1011, 0b1100, 0b1000, 0b1000, 0b1000]),
        's' => (4, [0, 0, 0b0111, 0b1000, 0b0110, 0b0001, 0b1110]),
        't' => (4, [0b0100, 0b0100, 0b1111, 0b0100, 0b0100, 0b0100, 0b0011]),
        'u' => (4, [0, 0, 0b1001, 0b1001, 0b1001, 0b1001, 0b0111]),
        'v' => (5, [0, 0, 0b10001, 0b10001, 0b10001, 0b01010, 0b00100]),
        'w' => (5, [0, 0, 0b10001, 0b10001, 0b10101, 0b10101, 0b01010]),
        'x' => (5, [0, 0, 0b10001, 0b01010, 0b00100, 0b01010, 0b10001]),
        'y' => (4, [0, 0, 0b1001, 0b1001, 0b0111, 0b0001, 0b0110]),
        'z' => (4, [0, 0, 0b1111, 0b0010, 0b0100, 0b1000, 0b1111]),
        ' ' => (3, [0; ROWS as usize]),
        _ => return None,
    })
}

/// Whether every character of `text` has a glyph.
#[cfg(test)]
pub fn supports(text: &str) -> bool {
    text.chars().all(|c| glyph(c).is_some())
}

/// Width in pixels of `text` at `scale`, with one font pixel between glyphs.
pub fn text_width(text: &str, scale: i32) -> i32 {
    let units: i32 = text
        .chars()
        .filter_map(glyph)
        .map(|(w, _)| i32::from(w) + 1)
        .sum();
    (units - 1).max(0) * scale
}

/// Draws `text` with its top-left corner at `(x, y)`. Characters without a
/// glyph are skipped.
pub fn draw_text(canvas: &mut LumaCanvas<'_>, x: i32, y: i32, scale: i32, text: &str, value: u8) {
    let mut cx = x;
    for (width, rows) in text.chars().filter_map(glyph) {
        let width = i32::from(width);
        for (row, bits) in (0..).zip(rows) {
            for col in 0..width {
                if bits >> (width - 1 - col) & 1 == 1 {
                    let px = Rect::new(cx + col * scale, y + row * scale, scale, scale);
                    canvas.fill_rect(px, value);
                }
            }
        }
        cx += (width + 1) * scale;
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::pattern::canvas::LumaImage;

    #[test]
    fn widths_add_up() {
        assert_eq!(text_width("", 3), 0);
        assert_eq!(text_width("1", 1), 5);
        assert_eq!(text_width("1.5", 2), (5 + 1 + 2 + 1 + 5) * 2);
        assert!(supports("1920×1080 · 29.97 fps · 1:00:00.5"));
        assert!(supports("github.com/AlexHayton/av-drift-detector"));
        assert!(supports("abcdefghijklmnopqrstuvwxyz"));
        assert!(!supports("1920X1080"));
    }

    #[test]
    fn glyphs_fit_their_widths() {
        for ch in "0123456789AHabcdefghijklmnopqrstuvwxyz×·.:/- ".chars() {
            let (width, rows) = glyph(ch).unwrap();
            for bits in rows {
                assert_eq!(bits >> width, 0, "{ch:?} has pixels beyond its width");
            }
        }
    }

    #[test]
    fn draws_within_its_box() {
        let mut img = LumaImage::new(80, 20, 0);
        let text = "12×3 · 4.5 fps";
        let (x, y, scale) = (2, 3, 1);
        draw_text(&mut img.canvas(), x, y, scale, text, 200);
        let w = text_width(text, scale);
        for py in 0..20 {
            for px in 0..80 {
                let inside =
                    (x..x + w).contains(&(px as i32)) && (y..y + ROWS).contains(&(py as i32));
                if !inside {
                    assert_eq!(img.view().get(px, py), 0, "pixel ({px}, {py})");
                }
            }
        }
        // The first glyph, `1`, has its top pixel in the middle column.
        assert_eq!(img.view().get(4, 3), 200);
    }
}