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/* |
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* riff-chunks: Read and write the chunks of RIFF and RIFX files. |
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* https://github.com/rochars/riff-chunks |
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* |
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* Copyright (c) 2017-2018 Rafael da Silva Rocha. |
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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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/** |
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* @fileoverview The riff-chunks API. |
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*/ |
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/** @module riffChunks */ |
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import {unpackFrom, unpackString} from './byte-data.js'; |
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/** @private */ |
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const uInt32_ = {bits: 32}; |
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/** @type {number} */ |
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let head_ = 0; |
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/** |
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* Return the chunks in a RIFF/RIFX file. |
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* @param {!Uint8Array} buffer The file bytes. |
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* @return {!Object} The RIFF chunks. |
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*/ |
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export default function riffChunks(buffer) { |
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head_ = 0; |
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let chunkId = getChunkId_(buffer, 0); |
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uInt32_.be = chunkId == 'RIFX'; |
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let format = unpackString(buffer, 8, 4); |
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head_ += 4; |
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return { |
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chunkId: chunkId, |
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chunkSize: getChunkSize_(buffer, 0), |
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format: format, |
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subChunks: getSubChunksIndex_(buffer) |
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}; |
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} |
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/** |
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* Return the sub chunks of a RIFF file. |
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* @param {!Uint8Array} buffer the RIFF file bytes. |
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* @return {!Array<Object>} The subchunks of a RIFF/RIFX or LIST chunk. |
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* @private |
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*/ |
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function getSubChunksIndex_(buffer) { |
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let chunks = []; |
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let i = head_; |
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while(i <= buffer.length - 8) { |
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chunks.push(getSubChunkIndex_(buffer, i)); |
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i += 8 + chunks[chunks.length - 1].chunkSize; |
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i = i % 2 ? i + 1 : i; |
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} |
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return chunks; |
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} |
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/** |
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* Return a sub chunk from a RIFF file. |
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* @param {!Uint8Array} buffer the RIFF file bytes. |
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* @param {number} index The start index of the chunk. |
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* @return {!Object} A subchunk of a RIFF/RIFX or LIST chunk. |
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* @private |
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*/ |
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function getSubChunkIndex_(buffer, index) { |
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let chunk = { |
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chunkId: getChunkId_(buffer, index), |
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chunkSize: getChunkSize_(buffer, index), |
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}; |
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if (chunk.chunkId == 'LIST') { |
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chunk.format = unpackString(buffer, index + 8, 4); |
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head_ += 4; |
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chunk.subChunks = getSubChunksIndex_(buffer); |
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} else { |
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let realChunkSize = chunk.chunkSize % 2 ? |
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chunk.chunkSize + 1 : chunk.chunkSize; |
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head_ = index + 8 + realChunkSize; |
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chunk.chunkData = { |
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start: index + 8, |
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end: head_ |
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}; |
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} |
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return chunk; |
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} |
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/** |
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* Return the fourCC_ of a chunk. |
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* @param {!Uint8Array} buffer the RIFF file bytes. |
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* @param {number} index The start index of the chunk. |
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* @return {string} The id of the chunk. |
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* @private |
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*/ |
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function getChunkId_(buffer, index) { |
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head_ += 4; |
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return unpackString(buffer, index, 4); |
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} |
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/** |
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* Return the size of a chunk. |
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* @param {!Uint8Array} buffer the RIFF file bytes. |
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* @param {number} index The start index of the chunk. |
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* @return {number} The size of the chunk without the id and size fields. |
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* @private |
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*/ |
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function getChunkSize_(buffer, index) { |
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head_ += 4; |
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return unpackFrom(buffer, uInt32_, index + 4); |
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} |
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rochars /
wavefile
