wavefile/lib/wavefile-tag-editor.js

Create, read and write wav files according to the specs.

/*
 * Copyright (c) 2017-2019 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 The WaveFileTagEditor class.
 * @see https://github.com/rochars/wavefile
 */

import { WaveFileCreator } from './wavefile-creator';

/**
 * A class to edit meta information in wav files.
 * @extends WaveFileCreator
 * @ignore
 */
export class WaveFileTagEditor extends WaveFileCreator {

  /**
   * Return the value of a RIFF tag in the INFO chunk.
   * @param {string} tag The tag name.
   * @return {?string} The value if the tag is found, null otherwise.
   */
  getTag(tag) {
    /** @type {!Object} */
    let index = this.getTagIndex_(tag);
    if (index.TAG !== null) {
      return this.LIST[index.LIST].subChunks[index.TAG].value;
    }
    return null;
  }

  /**
   * Write a RIFF tag in the INFO chunk. If the tag do not exist,
   * then it is created. It if exists, it is overwritten.
   * @param {string} tag The tag name.
   * @param {string} value The tag value.
   * @throws {Error} If the tag name is not valid.
   */
  setTag(tag, value) {
    tag = fixRIFFTag_(tag);
    /** @type {!Object} */
    let index = this.getTagIndex_(tag);
    if (index.TAG !== null) {
      this.LIST[index.LIST].subChunks[index.TAG].chunkSize =
        value.length + 1;
      this.LIST[index.LIST].subChunks[index.TAG].value = value;
    } else if (index.LIST !== null) {
      this.LIST[index.LIST].subChunks.push({
        chunkId: tag,
        chunkSize: value.length + 1,
        value: value});
    } else {
      this.LIST.push({
        chunkId: 'LIST',
        chunkSize: 8 + value.length + 1,
        format: 'INFO',
        subChunks: []});
      this.LIST[this.LIST.length - 1].subChunks.push({
        chunkId: tag,
        chunkSize: value.length + 1,
        value: value});
    }
  }

  /**
   * Remove a RIFF tag from the INFO chunk.
   * @param {string} tag The tag name.
   * @return {boolean} True if a tag was deleted.
   */
  deleteTag(tag) {
    /** @type {!Object} */
    let index = this.getTagIndex_(tag);
    if (index.TAG !== null) {
      this.LIST[index.LIST].subChunks.splice(index.TAG, 1);
      return true;
    }
    return false;
  }

  /**
   * Return a Object<tag, value> with the RIFF tags in the file.
   * @return {!Object<string, string>} The file tags.
   */
  listTags() {
    /** @type {?number} */
    let index = this.getLISTIndex('INFO');
    /** @type {!Object} */
    let tags = {};
    if (index !== null) {
      for (let i = 0, len = this.LIST[index].subChunks.length; i < len; i++) {
        tags[this.LIST[index].subChunks[i].chunkId] =
          this.LIST[index].subChunks[i].value;
      }
    }
    return tags;
  }

  /**
   * Return the index of a list by its type.
   * @param {string} listType The list type ('adtl', 'INFO')
   * @return {?number}
   * @protected
   */
  getLISTIndex(listType) {
    for (let i = 0, len = this.LIST.length; i < len; i++) {
      if (this.LIST[i].format == listType) {
        return i;
      }
    }
    return null;
  }

  /**
   * Return the index of a tag in a FILE chunk.
   * @param {string} tag The tag name.
   * @return {!Object<string, ?number>}
   *    Object.LIST is the INFO index in LIST
   *    Object.TAG is the tag index in the INFO
   * @private
   */
  getTagIndex_(tag) {
    /** @type {!Object<string, ?number>} */
    let index = {LIST: null, TAG: null};
    for (let i = 0, len = this.LIST.length; i < len; i++) {
      if (this.LIST[i].format == 'INFO') {
        index.LIST = i;
        for (let j=0, subLen = this.LIST[i].subChunks.length; j < subLen; j++) {
          if (this.LIST[i].subChunks[j].chunkId == tag) {
            index.TAG = j;
            break;
          }
        }
        break;
      }
    }
    return index;
  }
}

/**
 * Fix a RIFF tag format if possible, throw an error otherwise.
 * @param {string} tag The tag name.
 * @return {string} The tag name in proper fourCC format.
 * @private
 */
function fixRIFFTag_(tag) {
  if (tag.constructor !== String) {
    throw new Error('Invalid tag name.');
  } else if (tag.length < 4) {
    for (let i = 0, len = 4 - tag.length; i < len; i++) {
      tag += ' ';
    }
  }
  return tag;
}