index.js ➔ decodeSample_ - Code Metrics - Inspection of "Update version to 2.0.0" - rochars/imaadpcm - Measure and Improve Code Quality continuously with Scrutinizer

Passed

Push — master ( f5fd42...ebd91d )

by Rafael S.

created 2018-06-17 04:20 UTC

index.js ➔ decodeSample_ C

↳ Parent: index.js

Complexity

Conditions	7
Paths	48

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Importance

Changes	3
Bugs	0	Features	0

Metric	Value
cc	7
c	3
b	0
f	0
nc	48
nop	1
dl	0
loc	25
rs	6.7272

/*
 * imaadpcm: IMA ADPCM codec in JavaScript.
 * https://github.com/rochars/imaadpcm
 *
 * Copyright (c) 2017-2018 Rafael da Silva Rocha.
 *
 * 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 imaadpcm public API and private methods.
 */

/** @module imaadpcm */

/**
 * @type {!Array<number>}
 * @private
 */
const INDEX_TABLE = [
    -1, -1, -1, -1, 2, 4, 6, 8,
    -1, -1, -1, -1, 2, 4, 6, 8];
/**
 * @type {!Array<number>}
 * @private
 */
const STEP_TABLE = [
    7, 8, 9, 10, 11, 12, 13, 14,
    16, 17, 19, 21, 23, 25, 28, 31,
    34, 37, 41, 45, 50, 55, 60, 66,
    73, 80, 88, 97, 107, 118, 130, 143,
    157, 173, 190, 209, 230, 253, 279, 307,
    337, 371, 408, 449, 494, 544, 598, 658,
    724, 796, 876, 963, 1060, 1166, 1282, 1411,
    1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024,
    3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
    7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
    15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794,
    32767];
/**
 * @type {number}
 * @private
 */
let encoderPredicted_ = 0;
/**
 * @type {number}
 * @private
 */
let encoderIndex_ = 0;
/**
 * @type {number}
 * @private
 */
let encoderStep_ = 7;

/**
 * @type {number}
 * @private
 */
let decoderPredicted_ = 0;
/**
 * @type {number}
 * @private
 */
let decoderIndex_ = 0;
/**
 * @type {number}
 * @private
 */
let decoderStep_ = 7;

/**
 * Encode 16-bit PCM samples into 4-bit IMA ADPCM samples.
 * @param {!Array<number>} samples A array of samples.
 * @return {!Array<number>}
 */
function encode(samples) {
    /** @type {!Array<number>} */
    let adpcmSamples = [];
    /** @type {Array<number>} */
    let block = [];
    for (let i=0; i<samples.length; i++) {
        block.push(samples[i]);
        if ((i % 505 == 0 && i != 0) || i == samples.length - 1) {
            adpcmSamples = adpcmSamples.concat(encodeBlock(block));
            block = [];
        }
    }
    return adpcmSamples;
}

/**
 * Decode IMA ADPCM samples into 16-bit PCM samples.
 * @param {!Array<number>} adpcmSamples A array of ADPCM samples.
 * @param {number} blockAlign The block size.
 * @return {!Array<number>}
 */
function decode(adpcmSamples, blockAlign=256) {
    /** @type {!Array<number>} */
    let samples = [];
    /** @type {!Array<number>} */
    let block = [];
    for (let i=0; i<adpcmSamples.length; i++) {
        if (i % blockAlign == 0 && i != 0) {            
            samples = samples.concat(decodeBlock(block));
            block = [];
        }
        block.push(adpcmSamples[i]);
    }
    return samples;
}

/**
 * Encode a block of 505 16-bit samples as 4-bit ADPCM samples.
 * @param {!Array<number>} block A sample block of 505 samples.
 * @return {!Array<number>}
 */
function encodeBlock(block) {
    /** @type {!Array<number>} */
    let adpcmSamples = blockHead_(block[0]);
    for (let i=3; i<block.length; i+=2) {
        /** @type {number} */
        let sample2 = encodeSample_(block[i]);
        /** @type {number} */
        let sample = encodeSample_(block[i + 1]);
        adpcmSamples.push((sample << 4) | sample2);
    }
    while (adpcmSamples.length < 256) {
        adpcmSamples.push(0);
    }
    return adpcmSamples;
}

/**
 * Decode a block of ADPCM samples into 16-bit PCM samples.
 * @param {!Array<number>} block A adpcm sample block.
 * @return {!Array<number>}
 */
function decodeBlock(block) {
    decoderPredicted_ = sign_((block[1] << 8) | block[0]);
    decoderIndex_ = block[2];
    decoderStep_ = STEP_TABLE[decoderIndex_];
    /** @type {!Array<number>} */
    let result = [
            decoderPredicted_,
            sign_((block[3] << 8) | block[2])
        ];
    for (let i=4; i<block.length; i++) {
        /** @type {number} */
        let original_sample = block[i];
        /** @type {number} */
        let second_sample = original_sample >> 4;
        /** @type {number} */
        let first_sample = (second_sample << 4) ^ original_sample;
        result.push(decodeSample_(first_sample));
        result.push(decodeSample_(second_sample));
    }
    return result;
}

/**
 * Sign a 16-bit integer.
 * @param {number} num A 16-bit integer.
 * @return {number}
 * @private
 */
function sign_(num) {
    return num > 32768 ? num - 65536 : num;
}

/**
 * Compress a 16-bit PCM sample into a 4-bit ADPCM sample.
 * @param {number} sample The sample.
 * @return {number}
 * @private
 */
function encodeSample_(sample) {
    /** @type {number} */
    let delta = sample - encoderPredicted_;
    /** @type {number} */
    let value = 0;
    if (delta >= 0) {
        value = 0;
    } else {
        value = 8;
        delta = -delta;
    }
    /** @type {number} */
    let step = STEP_TABLE[encoderIndex_];
    /** @type {number} */
    let diff = step >> 3;
    if (delta > step) {
        value |= 4;
        delta -= step;
        diff += step;
    }
    step >>= 1;
    if (delta > step) {
        value |= 2;
        delta -= step;
        diff += step;
    }
    step >>= 1;
    if (delta > step) {
        value |= 1;
        diff += step;
    }
    updateEncoder_(value, diff);
    return value;
}

/**
 * Set the value for encoderPredicted_ and encoderIndex_
 * after each sample is compressed.
 * @param {number} value The compressed ADPCM sample
 * @param {number} diff The calculated difference
 * @private
 */
function updateEncoder_(value, diff) {
    if (value & 8) {

        encoderPredicted_ -= diff;
    } else {
        encoderPredicted_ += diff;
    }
    if (encoderPredicted_ < -0x8000) {
        encoderPredicted_ = -0x8000;
    } else if (encoderPredicted_ > 0x7fff) {
        encoderPredicted_ = 0x7fff;
    }
    encoderIndex_ += INDEX_TABLE[value & 7];
    if (encoderIndex_ < 0) {
        encoderIndex_ = 0;
    } else if (encoderIndex_ > 88) {
        encoderIndex_ = 88;
    }
}

/**
 * Decode a 4-bit ADPCM sample into a 16-bit PCM sample.
 * @param {number} nibble A 4-bit adpcm sample.
 * @return {number}
 * @private
 */
function decodeSample_(nibble) {
    /** @type {number} */
    let difference = 0;
    if (nibble & 4) {

        difference += decoderStep_;
    }
    if (nibble & 2) {

        difference += decoderStep_ >> 1;
    }
    if (nibble & 1) {

        difference += decoderStep_ >> 2;
    }
    difference += decoderStep_ >> 3;
    if (nibble & 8) {

        difference = -difference;
    }
    decoderPredicted_ += difference;
    if (decoderPredicted_ > 32767) {
        decoderPredicted_ = 32767;
    } else if (decoderPredicted_ < -32767) {
        decoderPredicted_ = -32767;
    }
    updateDecoder_(nibble);
    return decoderPredicted_;
}

/**
 * Update the index and step after decoding a sample.
 * @param {number} nibble A 4-bit adpcm sample.
 * @private
 */
function updateDecoder_(nibble) {
    decoderIndex_ += INDEX_TABLE[nibble];
    if (decoderIndex_ < 0) {
        decoderIndex_ = 0;
    } else if (decoderIndex_ > 88) {
        decoderIndex_ = 88;
    }
    decoderStep_ = STEP_TABLE[decoderIndex_];
}

/**
 * Return the head of a ADPCM sample block.
 * @param {number} sample The first sample of the block.
 * @return {!Array<number>}
 * @private
 */
function blockHead_(sample) {
    encodeSample_(sample);
    /** @type {!Array<number>} */
    let adpcmSamples = [];
    adpcmSamples.push(sample & 0xFF);
    adpcmSamples.push((sample >> 8) & 0xFF);
    adpcmSamples.push(encoderIndex_);
    adpcmSamples.push(0);
    return adpcmSamples;
}

/** @export */
module.exports.encode = encode;
/** @export */
module.exports.decode = decode;
/** @export */
module.exports.encodeBlock = encodeBlock;
/** @export */
module.exports.decodeBlock = decodeBlock;


1			/*
2			* imaadpcm: IMA ADPCM codec in JavaScript.
3			* https://github.com/rochars/imaadpcm
4			*
5			* Copyright (c) 2017-2018 Rafael da Silva Rocha.
6			*
7			* Permission is hereby granted, free of charge, to any person obtaining
8			* a copy of this software and associated documentation files (the
9			* "Software"), to deal in the Software without restriction, including
10			* without limitation the rights to use, copy, modify, merge, publish,
11			* distribute, sublicense, and/or sell copies of the Software, and to
12			* permit persons to whom the Software is furnished to do so, subject to
13			* the following conditions:
14			*
15			* The above copyright notice and this permission notice shall be
16			* included in all copies or substantial portions of the Software.
17			*
18			* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
19			* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20			* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
21			* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
22			* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
23			* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
24			* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25			*
26			*/
27
28			/**
29			* @fileoverview imaadpcm public API and private methods.
30			*/
31
32			/** @module imaadpcm */
33
34			/**
35			* @type {!Array<number>}
36			* @private
37			*/
38			const INDEX_TABLE = [
39			-1, -1, -1, -1, 2, 4, 6, 8,
40			-1, -1, -1, -1, 2, 4, 6, 8];
41			/**
42			* @type {!Array<number>}
43			* @private
44			*/
45			const STEP_TABLE = [
46			7, 8, 9, 10, 11, 12, 13, 14,
47			16, 17, 19, 21, 23, 25, 28, 31,
48			34, 37, 41, 45, 50, 55, 60, 66,
49			73, 80, 88, 97, 107, 118, 130, 143,
50			157, 173, 190, 209, 230, 253, 279, 307,
51			337, 371, 408, 449, 494, 544, 598, 658,
52			724, 796, 876, 963, 1060, 1166, 1282, 1411,
53			1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024,
54			3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
55			7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
56			15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794,
57			32767];
58			/**
59			* @type {number}
60			* @private
61			*/
62			let encoderPredicted_ = 0;
63			/**
64			* @type {number}
65			* @private
66			*/
67			let encoderIndex_ = 0;
68			/**
69			* @type {number}
70			* @private
71			*/
72			let encoderStep_ = 7;
			0 ignored issues – show Unused Code introduced 2018-06-17 03:48 UTC by Report Bug Copy Issue Report The variable `encoderStep_` seems to be never used. Consider removing it. Loading history...
73			/**
74			* @type {number}
75			* @private
76			*/
77			let decoderPredicted_ = 0;
78			/**
79			* @type {number}
80			* @private
81			*/
82			let decoderIndex_ = 0;
83			/**
84			* @type {number}
85			* @private
86			*/
87			let decoderStep_ = 7;
88
89			/**
90			* Encode 16-bit PCM samples into 4-bit IMA ADPCM samples.
91			* @param {!Array<number>} samples A array of samples.
92			* @return {!Array<number>}
93			*/
94			function encode(samples) {
95			/** @type {!Array<number>} */
96			let adpcmSamples = [];
97			/** @type {Array<number>} */
98			let block = [];
99			for (let i=0; i<samples.length; i++) {
100			block.push(samples[i]);
101			if ((i % 505 == 0 && i != 0) \|\| i == samples.length - 1) {
102			adpcmSamples = adpcmSamples.concat(encodeBlock(block));
103			block = [];
104			}
105			}
106			return adpcmSamples;
107			}
108
109			/**
110			* Decode IMA ADPCM samples into 16-bit PCM samples.
111			* @param {!Array<number>} adpcmSamples A array of ADPCM samples.
112			* @param {number} blockAlign The block size.
113			* @return {!Array<number>}
114			*/
115			function decode(adpcmSamples, blockAlign=256) {
116			/** @type {!Array<number>} */
117			let samples = [];
118			/** @type {!Array<number>} */
119			let block = [];
120			for (let i=0; i<adpcmSamples.length; i++) {
121			if (i % blockAlign == 0 && i != 0) {
122			samples = samples.concat(decodeBlock(block));
123			block = [];
124			}
125			block.push(adpcmSamples[i]);
126			}
127			return samples;
128			}
129
130			/**
131			* Encode a block of 505 16-bit samples as 4-bit ADPCM samples.
132			* @param {!Array<number>} block A sample block of 505 samples.
133			* @return {!Array<number>}
134			*/
135			function encodeBlock(block) {
136			/** @type {!Array<number>} */
137			let adpcmSamples = blockHead_(block[0]);
138			for (let i=3; i<block.length; i+=2) {
139			/** @type {number} */
140			let sample2 = encodeSample_(block[i]);
141			/** @type {number} */
142			let sample = encodeSample_(block[i + 1]);
143			adpcmSamples.push((sample << 4) \| sample2);
144			}
145			while (adpcmSamples.length < 256) {
146			adpcmSamples.push(0);
147			}
148			return adpcmSamples;
149			}
150
151			/**
152			* Decode a block of ADPCM samples into 16-bit PCM samples.
153			* @param {!Array<number>} block A adpcm sample block.
154			* @return {!Array<number>}
155			*/
156			function decodeBlock(block) {
157			decoderPredicted_ = sign_((block[1] << 8) \| block[0]);
158			decoderIndex_ = block[2];
159			decoderStep_ = STEP_TABLE[decoderIndex_];
160			/** @type {!Array<number>} */
161			let result = [
162			decoderPredicted_,
163			sign_((block[3] << 8) \| block[2])
164			];
165			for (let i=4; i<block.length; i++) {
166			/** @type {number} */
167			let original_sample = block[i];
168			/** @type {number} */
169			let second_sample = original_sample >> 4;
170			/** @type {number} */
171			let first_sample = (second_sample << 4) ^ original_sample;
172			result.push(decodeSample_(first_sample));
173			result.push(decodeSample_(second_sample));
174			}
175			return result;
176			}
177
178			/**
179			* Sign a 16-bit integer.
180			* @param {number} num A 16-bit integer.
181			* @return {number}
182			* @private
183			*/
184			function sign_(num) {
185			return num > 32768 ? num - 65536 : num;
186			}
187
188			/**
189			* Compress a 16-bit PCM sample into a 4-bit ADPCM sample.
190			* @param {number} sample The sample.
191			* @return {number}
192			* @private
193			*/
194			function encodeSample_(sample) {
195			/** @type {number} */
196			let delta = sample - encoderPredicted_;
197			/** @type {number} */
198			let value = 0;
199			if (delta >= 0) {
200			value = 0;
201			} else {
202			value = 8;
203			delta = -delta;
204			}
205			/** @type {number} */
206			let step = STEP_TABLE[encoderIndex_];
207			/** @type {number} */
208			let diff = step >> 3;
209			if (delta > step) {
210			value \|= 4;
211			delta -= step;
212			diff += step;
213			}
214			step >>= 1;
215			if (delta > step) {
216			value \|= 2;
217			delta -= step;
218			diff += step;
219			}
220			step >>= 1;
221			if (delta > step) {
222			value \|= 1;
223			diff += step;
224			}
225			updateEncoder_(value, diff);
226			return value;
227			}
228
229			/**
230			* Set the value for encoderPredicted_ and encoderIndex_
231			* after each sample is compressed.
232			* @param {number} value The compressed ADPCM sample
233			* @param {number} diff The calculated difference
234			* @private
235			*/
236			function updateEncoder_(value, diff) {
237			if (value & 8) {
			0 ignored issues – show introduced 2018-04-26 05:45 UTC by Report Bug Copy Issue Report You have used a bitwise operator `&` in a condition. Did you maybe want to use the logical operator `&&` Loading history...
238			encoderPredicted_ -= diff;
239			} else {
240			encoderPredicted_ += diff;
241			}
242			if (encoderPredicted_ < -0x8000) {
243			encoderPredicted_ = -0x8000;
244			} else if (encoderPredicted_ > 0x7fff) {
245			encoderPredicted_ = 0x7fff;
246			}
247			encoderIndex_ += INDEX_TABLE[value & 7];
248			if (encoderIndex_ < 0) {
249			encoderIndex_ = 0;
250			} else if (encoderIndex_ > 88) {
251			encoderIndex_ = 88;
252			}
253			}
254
255			/**
256			* Decode a 4-bit ADPCM sample into a 16-bit PCM sample.
257			* @param {number} nibble A 4-bit adpcm sample.
258			* @return {number}
259			* @private
260			*/
261			function decodeSample_(nibble) {
262			/** @type {number} */
263			let difference = 0;
264			if (nibble & 4) {
			0 ignored issues – show introduced 2018-04-20 08:54 UTC by Report Bug Copy Issue Report You have used a bitwise operator `&` in a condition. Did you maybe want to use the logical operator `&&` Loading history...
265			difference += decoderStep_;
266			}
267			if (nibble & 2) {
			0 ignored issues – show introduced 2018-04-20 08:54 UTC by Report Bug Copy Issue Report You have used a bitwise operator `&` in a condition. Did you maybe want to use the logical operator `&&` Loading history...
268			difference += decoderStep_ >> 1;
269			}
270			if (nibble & 1) {
			0 ignored issues – show introduced 2018-04-20 08:54 UTC by Report Bug Copy Issue Report You have used a bitwise operator `&` in a condition. Did you maybe want to use the logical operator `&&` Loading history...
271			difference += decoderStep_ >> 2;
272			}
273			difference += decoderStep_ >> 3;
274			if (nibble & 8) {
			0 ignored issues – show introduced 2018-04-20 08:54 UTC by Report Bug Copy Issue Report You have used a bitwise operator `&` in a condition. Did you maybe want to use the logical operator `&&` Loading history...
275			difference = -difference;
276			}
277			decoderPredicted_ += difference;
278			if (decoderPredicted_ > 32767) {
279			decoderPredicted_ = 32767;
280			} else if (decoderPredicted_ < -32767) {
281			decoderPredicted_ = -32767;
282			}
283			updateDecoder_(nibble);
284			return decoderPredicted_;
285			}
286
287			/**
288			* Update the index and step after decoding a sample.
289			* @param {number} nibble A 4-bit adpcm sample.
290			* @private
291			*/
292			function updateDecoder_(nibble) {
293			decoderIndex_ += INDEX_TABLE[nibble];
294			if (decoderIndex_ < 0) {
295			decoderIndex_ = 0;
296			} else if (decoderIndex_ > 88) {
297			decoderIndex_ = 88;
298			}
299			decoderStep_ = STEP_TABLE[decoderIndex_];
300			}
301
302			/**
303			* Return the head of a ADPCM sample block.
304			* @param {number} sample The first sample of the block.
305			* @return {!Array<number>}
306			* @private
307			*/
308			function blockHead_(sample) {
309			encodeSample_(sample);
310			/** @type {!Array<number>} */
311			let adpcmSamples = [];
312			adpcmSamples.push(sample & 0xFF);
313			adpcmSamples.push((sample >> 8) & 0xFF);
314			adpcmSamples.push(encoderIndex_);
315			adpcmSamples.push(0);
316			return adpcmSamples;
317			}
318
319			/** @export */
320			module.exports.encode = encode;
321			/** @export */
322			module.exports.decode = decode;
323			/** @export */
324			module.exports.encodeBlock = encodeBlock;
325			/** @export */
326			module.exports.decodeBlock = decodeBlock;
327

rochars / imaadpcm

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index.js ➔ decodeSample_ C

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