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
|
async function checkEncoderSupport(test, config) {
assert_equals("function", typeof VideoEncoder.isConfigSupported);
let supported = false;
try {
const support = await VideoEncoder.isConfigSupported(config);
supported = support.supported;
} catch (e) {}
assert_implements_optional(supported, 'Unsupported config: ' +
JSON.stringify(config));
}
function fourColorsFrame(ctx, width, height, text) {
const kYellow = "#FFFF00";
const kRed = "#FF0000";
const kBlue = "#0000FF";
const kGreen = "#00FF00";
ctx.fillStyle = kYellow;
ctx.fillRect(0, 0, width / 2, height / 2);
ctx.fillStyle = kRed;
ctx.fillRect(width / 2, 0, width / 2, height / 2);
ctx.fillStyle = kBlue;
ctx.fillRect(0, height / 2, width / 2, height / 2);
ctx.fillStyle = kGreen;
ctx.fillRect(width / 2, height / 2, width / 2, height / 2);
ctx.fillStyle = 'white';
ctx.font = (height / 10) + 'px sans-serif';
ctx.fillText(text, width / 2, height / 2);
}
// Paints |count| black dots on the |ctx|, so their presence can be validated
// later. This is an analog of the most basic bar code.
function putBlackDots(ctx, width, height, count) {
ctx.fillStyle = 'black';
const dot_size = 10;
const step = dot_size * 3;
for (let i = 1; i <= count; i++) {
let x = i * step;
let y = step * (x / width + 1);
x %= width;
ctx.fillRect(x, y, dot_size, dot_size);
}
}
// Validates that frame has |count| black dots in predefined places.
function validateBlackDots(frame, count) {
const width = frame.displayWidth;
const height = frame.displayHeight;
let cnv = new OffscreenCanvas(width, height);
var ctx = cnv.getContext('2d');
ctx.drawImage(frame, 0, 0);
const dot_size = 10;
const step = dot_size * 3;
for (let i = 1; i <= count; i++) {
let x = i * step + dot_size / 2;
let y = step * (x / width + 1) + dot_size / 2;
x %= width;
if (x)
x = x -1;
if (y)
y = y -1;
let rgba = ctx.getImageData(x, y, 2, 2).data;
const tolerance = 40;
if ((rgba[0] > tolerance || rgba[1] > tolerance || rgba[2] > tolerance)
&& (rgba[4] > tolerance || rgba[5] > tolerance || rgba[6] > tolerance)
&& (rgba[8] > tolerance || rgba[9] > tolerance || rgba[10] > tolerance)
&& (rgba[12] > tolerance || rgba[13] > tolerance || rgba[14] > tolerance)) {
// The dot is too bright to be a black dot.
return false;
}
}
return true;
}
function createFrame(width, height, ts = 0) {
let duration = 33333; // 30fps
let text = ts.toString();
let cnv = new OffscreenCanvas(width, height);
var ctx = cnv.getContext('2d');
fourColorsFrame(ctx, width, height, text);
return new VideoFrame(cnv, { timestamp: ts, duration });
}
function createDottedFrame(width, height, dots, ts) {
if (ts === undefined)
ts = dots;
let duration = 33333; // 30fps
let text = ts.toString();
let cnv = new OffscreenCanvas(width, height);
var ctx = cnv.getContext('2d');
fourColorsFrame(ctx, width, height, text);
putBlackDots(ctx, width, height, dots);
return new VideoFrame(cnv, { timestamp: ts, duration });
}
|
