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/* |
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* Copyright (c) 2019 Rafael da Silva Rocha. |
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* Copyright (c) 2017 Brett Zamir, 2012 Niklas von Hertzen |
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* |
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* Permission is hereby granted, free of charge, to any person obtaining |
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* a copy of this software and associated documentation files (the |
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* "Software"), to deal in the Software without restriction, including |
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* without limitation the rights to use, copy, modify, merge, publish, |
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* distribute, sublicense, and/or sell copies of the Software, and to |
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* permit persons to whom the Software is furnished to do so, subject to |
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* the following conditions: |
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* |
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* The above copyright notice and this permission notice shall be |
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* included in all copies or substantial portions of the Software. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE |
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION |
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION |
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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* |
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*/ |
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const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'; |
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/** |
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* Encode a byte buffer as a base64 string. |
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* @param {!Uint8Array} bytes The buffer. |
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* @return {string} A .wav file as a DataURI. |
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*/ |
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export function encode(bytes) { |
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/** @type {string} */ |
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let base64 = ''; |
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for (let i = 0; i < bytes.length; i += 3) { |
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base64 += chars[bytes[i] >> 2]; |
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base64 += chars[(bytes[i] & 3) << 4 | bytes[i + 1] >> 4]; |
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base64 += chars[(bytes[i + 1] & 15) << 2 | bytes[i + 2] >> 6]; |
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base64 += chars[bytes[i + 2] & 63]; |
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} |
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if (bytes.length % 3 === 2) { |
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base64 = base64.substring(0, base64.length - 1) + '='; |
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} else if (bytes.length % 3 === 1) { |
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base64 = base64.substring(0, base64.length - 2) + '=='; |
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} |
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return base64; |
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} |
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/** |
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* Decode a base64 string as a byte as buffer. |
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* @param {string} base64 A .wav file as a DataURI. |
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* @return {!Uint8Array} A .wav file as a DataURI. |
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*/ |
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export function decode(base64) { |
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/** @type {!Uint8Array} */ |
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let lookup = new Uint8Array(256); |
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for (let i = 0; i < chars.length; i++) { |
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lookup[chars.charCodeAt(i)] = i; |
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} |
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/** @type {number} */ |
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let bufferLength = base64.length * 0.75; |
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if (base64[base64.length - 1] === '=') { |
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bufferLength--; |
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if (base64[base64.length - 2] === '=') { |
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bufferLength--; |
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} |
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} |
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/** @type {!Uint8Array} */ |
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let bytes = new Uint8Array(bufferLength); |
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for (let i = 0, j = 0; i < base64.length; i += 4) { |
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/** @type {number} */ |
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let encoded1 = lookup[base64.charCodeAt(i)]; |
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/** @type {number} */ |
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let encoded2 = lookup[base64.charCodeAt(i + 1)]; |
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/** @type {number} */ |
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let encoded3 = lookup[base64.charCodeAt(i + 2)]; |
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/** @type {number} */ |
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let encoded4 = lookup[base64.charCodeAt(i + 3)]; |
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bytes[j++] = encoded1 << 2 | encoded2 >> 4; |
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bytes[j++] = (encoded2 & 15) << 4 | encoded3 >> 2; |
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bytes[j++] = (encoded3 & 3) << 6 | encoded4 & 63; |
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} |
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return bytes; |
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} |
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rochars /
wavefile
