Interpolator.constructor - Code Metrics - Inspection of "Update docs with v11.0" - rochars/wavefile - Measure and Improve Code Quality continuously with Scrutinizer

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by Rafael S.

created 2020-01-30 04:04 UTC

Interpolator.constructor A

↳ Parent: Interpolator

Complexity

Conditions

Size

Total Lines	40
Code Lines	13

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	4
eloc	13
dl	0
loc	40
rs	9.75
c	0
b	0
f	0

/*
 * Copyright (c) 2019 Rafael da Silva Rocha.
 * Copyright 2012 Spencer Cohen
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */

/**
 * @fileoverview The Interpolator class. Based on Smooth.js by Spencer Cohen.
 * @see https://github.com/rochars/wavefile
 * @see https://github.com/osuushi/Smooth.js
 */

/**
 * A class to get scaled values out of arrays.
 * @extends WaveFileReader
 */
export class Interpolator {
  
  /**
   * @param {number} scaleFrom the length of the original array.
   * @param {number} scaleTo The length of the new array.
   * @param {!Object} details The extra configuration, if needed.
   */
  constructor(scaleFrom, scaleTo, details) {
    /**
     * The length of the original array.
     * @type {number}
     */
    this.length_ = scaleFrom;
    /**
     * The scaling factor.
     * @type {number}
     */
    this.scaleFactor_ = (scaleFrom - 1) / scaleTo;
    /**
     * The interpolation function.
     * @type {Function}
     */
    this.interpolate = this.sinc;
    if (details.method === 'point') {
    	this.interpolate = this.point;
    } else if(details.method === 'linear') {
    	this.interpolate = this.linear;
    } else if(details.method === 'cubic') {
    	this.interpolate = this.cubic;
    }
    /**
     * The tanget factor for cubic interpolation.
     * @type {number}
     */
    this.tangentFactor_ = 1 - Math.max(0, Math.min(1, details.tension || 0));
    // Configure the kernel for sinc
    /**
     * The sinc filter size.
     * @type {number}
     */
    this.sincFilterSize_ = details.sincFilterSize || 1;
    /**
     * The sinc kernel.
     * @type {Function}
     */
    this.kernel_ = sincKernel_(details.sincWindow || window_);
  }

  /**
   * @param {number} t The index to interpolate.
   * @param {Array<number>|TypedArray} samples the original array.
   * @return {number} The interpolated value.
   */
  point(t, samples) {
    return this.getClippedInput_(Math.round(this.scaleFactor_ * t), samples);
  }

  /**
   * @param {number} t The index to interpolate.
   * @param {Array<number>|TypedArray} samples the original array.
   * @return {number} The interpolated value.
   */
  linear(t, samples) {
    t = this.scaleFactor_ * t;
    /** @type {number} */
    let k = Math.floor(t);
    t -= k;
    return (1 - t) *
    	this.getClippedInput_(k, samples) + t *
    	this.getClippedInput_(k + 1, samples);
  }

  /**
   * @param {number} t The index to interpolate.
   * @param {Array<number>|TypedArray} samples the original array.
   * @return {number} The interpolated value.
   */
  cubic(t, samples) {
    t = this.scaleFactor_ * t;
    /** @type {number} */
    let k = Math.floor(t);
    /** @type {Array<number>} */
    let m = [this.getTangent_(k, samples), this.getTangent_(k + 1, samples)];
    /** @type {Array<number>} */
    let p = [this.getClippedInput_(k, samples),
      this.getClippedInput_(k + 1, samples)];
    t -= k;
    /** @type {number} */
    let t2 = t * t;
    /** @type {number} */
    let t3 = t * t2;
    return (2 * t3 - 3 * t2 + 1) *
      p[0] + (t3 - 2 * t2 + t) *
      m[0] + (-2 * t3 + 3 * t2) *
      p[1] + (t3 - t2) * m[1];
  }

  /**
   * @param {number} t The index to interpolate.
   * @param {Array<number>|TypedArray} samples the original array.
   * @return {number} The interpolated value.
   */
  sinc(t, samples) {
    t = this.scaleFactor_ * t;
    /** @type {number} */
    let k = Math.floor(t);
    /** @type {number} */
    let ref = k - this.sincFilterSize_ + 1;
    /** @type {number} */
    let ref1 = k + this.sincFilterSize_;
    /** @type {number} */
    let sum = 0;
    for (let n = ref; n <= ref1; n++) {
      sum += this.kernel_(t - n) * this.getClippedInput_(n, samples);
    }
    return sum;
  }

  /**
   * @param {number} k The scaled index to interpolate.
   * @param {Array<number>|TypedArray} samples the original array.
   * @return {number} The tangent.
   * @private
   */
  getTangent_(k, samples) {
    return this.tangentFactor_ *
      (this.getClippedInput_(k + 1, samples) -
        this.getClippedInput_(k - 1, samples)) / 2;
  }

  /**
   * @param {number} t The scaled index to interpolate.
   * @param {Array<number>|TypedArray} samples the original array.
   * @return {number} The interpolated value.
   * @private
   */
  getClippedInput_(t, samples) {
    if ((0 <= t && t < this.length_)) {
      return samples[t];
    }
    return 0;
  }
}

/**
 * The default window function.
 * @param {number} x The sinc signal.
 * @return {number}
 * @private
 */
function window_(x) {
  return Math.exp(-x / 2 * x / 2);
}

/**
 * @param {Function} window The window function.
 * @return {Function}
 * @private
 */
function sincKernel_(window) {
  return function(x) { return sinc_(x) * window(x); };
}

/**
 * @param {number} x The sinc signal.
 * @return {number}
 * @private
 */
function sinc_(x) {
  if (x === 0) {
    return 1;
  }
  return Math.sin(Math.PI * x) / (Math.PI * x);
}


1			/*
2			* Copyright (c) 2019 Rafael da Silva Rocha.
3			* Copyright 2012 Spencer Cohen
4			*
5			* Permission is hereby granted, free of charge, to any person obtaining
6			* a copy of this software and associated documentation files (the
7			* "Software"), to deal in the Software without restriction, including
8			* without limitation the rights to use, copy, modify, merge, publish,
9			* distribute, sublicense, and/or sell copies of the Software, and to
10			* permit persons to whom the Software is furnished to do so, subject to
11			* the following conditions:
12			*
13			* The above copyright notice and this permission notice shall be
14			* included in all copies or substantial portions of the Software.
15			*
16			* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17			* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18			* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19			* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20			* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21			* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
22			* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23			*
24			*/
25
26			/**
27			* @fileoverview The Interpolator class. Based on Smooth.js by Spencer Cohen.
28			* @see https://github.com/rochars/wavefile
29			* @see https://github.com/osuushi/Smooth.js
30			*/
31
32			/**
33			* A class to get scaled values out of arrays.
34			* @extends WaveFileReader
35			*/
36			export class Interpolator {
37
38			/**
39			* @param {number} scaleFrom the length of the original array.
40			* @param {number} scaleTo The length of the new array.
41			* @param {!Object} details The extra configuration, if needed.
42			*/
43			constructor(scaleFrom, scaleTo, details) {
44			/**
45			* The length of the original array.
46			* @type {number}
47			*/
48			this.length_ = scaleFrom;
49			/**
50			* The scaling factor.
51			* @type {number}
52			*/
53			this.scaleFactor_ = (scaleFrom - 1) / scaleTo;
54			/**
55			* The interpolation function.
56			* @type {Function}
57			*/
58			this.interpolate = this.sinc;
59			if (details.method === 'point') {
60			this.interpolate = this.point;
61			} else if(details.method === 'linear') {
62			this.interpolate = this.linear;
63			} else if(details.method === 'cubic') {
64			this.interpolate = this.cubic;
65			}
66			/**
67			* The tanget factor for cubic interpolation.
68			* @type {number}
69			*/
70			this.tangentFactor_ = 1 - Math.max(0, Math.min(1, details.tension \|\| 0));
71			// Configure the kernel for sinc
72			/**
73			* The sinc filter size.
74			* @type {number}
75			*/
76			this.sincFilterSize_ = details.sincFilterSize \|\| 1;
77			/**
78			* The sinc kernel.
79			* @type {Function}
80			*/
81			this.kernel_ = sincKernel_(details.sincWindow \|\| window_);
82			}
83
84			/**
85			* @param {number} t The index to interpolate.
86			* @param {Array<number>\|TypedArray} samples the original array.
87			* @return {number} The interpolated value.
88			*/
89			point(t, samples) {
90			return this.getClippedInput_(Math.round(this.scaleFactor_ * t), samples);
91			}
92
93			/**
94			* @param {number} t The index to interpolate.
95			* @param {Array<number>\|TypedArray} samples the original array.
96			* @return {number} The interpolated value.
97			*/
98			linear(t, samples) {
99			t = this.scaleFactor_ * t;
100			/** @type {number} */
101			let k = Math.floor(t);
102			t -= k;
103			return (1 - t) *
104			this.getClippedInput_(k, samples) + t *
105			this.getClippedInput_(k + 1, samples);
106			}
107
108			/**
109			* @param {number} t The index to interpolate.
110			* @param {Array<number>\|TypedArray} samples the original array.
111			* @return {number} The interpolated value.
112			*/
113			cubic(t, samples) {
114			t = this.scaleFactor_ * t;
115			/** @type {number} */
116			let k = Math.floor(t);
117			/** @type {Array<number>} */
118			let m = [this.getTangent_(k, samples), this.getTangent_(k + 1, samples)];
119			/** @type {Array<number>} */
120			let p = [this.getClippedInput_(k, samples),
121			this.getClippedInput_(k + 1, samples)];
122			t -= k;
123			/** @type {number} */
124			let t2 = t * t;
125			/** @type {number} */
126			let t3 = t * t2;
127			return (2 * t3 - 3 * t2 + 1) *
128			p[0] + (t3 - 2 * t2 + t) *
129			m[0] + (-2 * t3 + 3 * t2) *
130			p[1] + (t3 - t2) * m[1];
131			}
132
133			/**
134			* @param {number} t The index to interpolate.
135			* @param {Array<number>\|TypedArray} samples the original array.
136			* @return {number} The interpolated value.
137			*/
138			sinc(t, samples) {
139			t = this.scaleFactor_ * t;
140			/** @type {number} */
141			let k = Math.floor(t);
142			/** @type {number} */
143			let ref = k - this.sincFilterSize_ + 1;
144			/** @type {number} */
145			let ref1 = k + this.sincFilterSize_;
146			/** @type {number} */
147			let sum = 0;
148			for (let n = ref; n <= ref1; n++) {
149			sum += this.kernel_(t - n) * this.getClippedInput_(n, samples);
150			}
151			return sum;
152			}
153
154			/**
155			* @param {number} k The scaled index to interpolate.
156			* @param {Array<number>\|TypedArray} samples the original array.
157			* @return {number} The tangent.
158			* @private
159			*/
160			getTangent_(k, samples) {
161			return this.tangentFactor_ *
162			(this.getClippedInput_(k + 1, samples) -
163			this.getClippedInput_(k - 1, samples)) / 2;
164			}
165
166			/**
167			* @param {number} t The scaled index to interpolate.
168			* @param {Array<number>\|TypedArray} samples the original array.
169			* @return {number} The interpolated value.
170			* @private
171			*/
172			getClippedInput_(t, samples) {
173			if ((0 <= t && t < this.length_)) {
174			return samples[t];
175			}
176			return 0;
177			}
178			}
179
180			/**
181			* The default window function.
182			* @param {number} x The sinc signal.
183			* @return {number}
184			* @private
185			*/
186			function window_(x) {
187			return Math.exp(-x / 2 * x / 2);
188			}
189
190			/**
191			* @param {Function} window The window function.
192			* @return {Function}
193			* @private
194			*/
195			function sincKernel_(window) {
196			return function(x) { return sinc_(x) * window(x); };
197			}
198
199			/**
200			* @param {number} x The sinc signal.
201			* @return {number}
202			* @private
203			*/
204			function sinc_(x) {
205			if (x === 0) {
206			return 1;
207			}
208			return Math.sin(Math.PI * x) / (Math.PI * x);
209			}
210

rochars / wavefile

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Interpolator.constructor A

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