// 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;
}
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