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