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
|
// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* @fileOverview This file includes legacy utility functions for the layout
* test.
*/
// How many frames in a WebAudio render quantum.
let RENDER_QUANTUM_FRAMES = 128;
// Compare two arrays (commonly extracted from buffer.getChannelData()) with
// constraints:
// options.thresholdSNR: Minimum allowed SNR between the actual and expected
// signal. The default value is 10000.
// options.thresholdDiffULP: Maximum allowed difference between the actual
// and expected signal in ULP(Unit in the last place). The default is 0.
// options.thresholdDiffCount: Maximum allowed number of sample differences
// which exceeds the threshold. The default is 0.
// options.bitDepth: The expected result is assumed to come from an audio
// file with this number of bits of precision. The default is 16.
function compareBuffersWithConstraints(should, actual, expected, options) {
if (!options)
options = {};
// Only print out the message if the lengths are different; the
// expectation is that they are the same, so don't clutter up the
// output.
if (actual.length !== expected.length) {
should(
actual.length === expected.length,
'Length of actual and expected buffers should match')
.beTrue();
}
let maxError = -1;
let diffCount = 0;
let errorPosition = -1;
let thresholdSNR = (options.thresholdSNR || 10000);
let thresholdDiffULP = (options.thresholdDiffULP || 0);
let thresholdDiffCount = (options.thresholdDiffCount || 0);
// By default, the bit depth is 16.
let bitDepth = (options.bitDepth || 16);
let scaleFactor = Math.pow(2, bitDepth - 1);
let noisePower = 0, signalPower = 0;
for (let i = 0; i < actual.length; i++) {
let diff = actual[i] - expected[i];
noisePower += diff * diff;
signalPower += expected[i] * expected[i];
if (Math.abs(diff) > maxError) {
maxError = Math.abs(diff);
errorPosition = i;
}
// The reference file is a 16-bit WAV file, so we will almost never get
// an exact match between it and the actual floating-point result.
if (Math.abs(diff) > scaleFactor)
diffCount++;
}
let snr = 10 * Math.log10(signalPower / noisePower);
let maxErrorULP = maxError * scaleFactor;
should(snr, 'SNR').beGreaterThanOrEqualTo(thresholdSNR);
should(
maxErrorULP,
options.prefix + ': Maximum difference (in ulp units (' + bitDepth +
'-bits))')
.beLessThanOrEqualTo(thresholdDiffULP);
should(diffCount, options.prefix + ': Number of differences between results')
.beLessThanOrEqualTo(thresholdDiffCount);
}
// Create an impulse in a buffer of length sampleFrameLength
function createImpulseBuffer(context, sampleFrameLength) {
let audioBuffer =
context.createBuffer(1, sampleFrameLength, context.sampleRate);
let n = audioBuffer.length;
let dataL = audioBuffer.getChannelData(0);
for (let k = 0; k < n; ++k) {
dataL[k] = 0;
}
dataL[0] = 1;
return audioBuffer;
}
// Create a buffer of the given length with a linear ramp having values 0 <= x <
// 1.
function createLinearRampBuffer(context, sampleFrameLength) {
let audioBuffer =
context.createBuffer(1, sampleFrameLength, context.sampleRate);
let n = audioBuffer.length;
let dataL = audioBuffer.getChannelData(0);
for (let i = 0; i < n; ++i)
dataL[i] = i / n;
return audioBuffer;
}
// Create an AudioBuffer of length |sampleFrameLength| having a constant value
// |constantValue|. If |constantValue| is a number, the buffer has one channel
// filled with that value. If |constantValue| is an array, the buffer is created
// wit a number of channels equal to the length of the array, and channel k is
// filled with the k'th element of the |constantValue| array.
function createConstantBuffer(context, sampleFrameLength, constantValue) {
let channels;
let values;
if (typeof constantValue === 'number') {
channels = 1;
values = [constantValue];
} else {
channels = constantValue.length;
values = constantValue;
}
let audioBuffer =
context.createBuffer(channels, sampleFrameLength, context.sampleRate);
let n = audioBuffer.length;
for (let c = 0; c < channels; ++c) {
let data = audioBuffer.getChannelData(c);
for (let i = 0; i < n; ++i)
data[i] = values[c];
}
return audioBuffer;
}
// Create a stereo impulse in a buffer of length sampleFrameLength
function createStereoImpulseBuffer(context, sampleFrameLength) {
let audioBuffer =
context.createBuffer(2, sampleFrameLength, context.sampleRate);
let n = audioBuffer.length;
let dataL = audioBuffer.getChannelData(0);
let dataR = audioBuffer.getChannelData(1);
for (let k = 0; k < n; ++k) {
dataL[k] = 0;
dataR[k] = 0;
}
dataL[0] = 1;
dataR[0] = 1;
return audioBuffer;
}
// Convert time (in seconds) to sample frames.
function timeToSampleFrame(time, sampleRate) {
return Math.floor(0.5 + time * sampleRate);
}
// Compute the number of sample frames consumed by noteGrainOn with
// the specified |grainOffset|, |duration|, and |sampleRate|.
function grainLengthInSampleFrames(grainOffset, duration, sampleRate) {
let startFrame = timeToSampleFrame(grainOffset, sampleRate);
let endFrame = timeToSampleFrame(grainOffset + duration, sampleRate);
return endFrame - startFrame;
}
// True if the number is not an infinity or NaN
function isValidNumber(x) {
return !isNaN(x) && (x != Infinity) && (x != -Infinity);
}
// Compute the (linear) signal-to-noise ratio between |actual| and
// |expected|. The result is NOT in dB! If the |actual| and
// |expected| have different lengths, the shorter length is used.
function computeSNR(actual, expected) {
let signalPower = 0;
let noisePower = 0;
let length = Math.min(actual.length, expected.length);
for (let k = 0; k < length; ++k) {
let diff = actual[k] - expected[k];
signalPower += expected[k] * expected[k];
noisePower += diff * diff;
}
return signalPower / noisePower;
}
|
