rochars / wavefile

index.js

/*
 * 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 The WaveFile class.
 * @see https://github.com/rochars/wavefile
 */

/** @module wavefile */

import bitDepthLib from './vendor/bitdepth.js';
import * as imaadpcm from './vendor/imaadpcm.js';
import * as alawmulaw from './vendor/alawmulaw.js';
import {encode, decode} from './vendor/base64-arraybuffer-es6.js';
import {unpackArray, packArrayTo, unpackArrayTo,
pack, packStringTo, packTo, packString} from './vendor/byte-data.js';

The variable packString seems to be never used. Consider removing it.

The variable packTo seems to be never used. Consider removing it.

The variable pack seems to be never used. Consider removing it.

The variable packStringTo seems to be never used. Consider removing it.

import {wavHeader, validateHeader_} from './lib/wavheader.js';
import {riffChunks, findChunk_} from './vendor/riff-chunks.js';
import BufferIO from './lib/bufferio.js';
import writeWavBuffer from './lib/wav-buffer-writer.js';
import readWavBuffer from './lib/wav-buffer-reader.js';

/**
 * Class representing a wav file.
 * @ignore
 */
export default class WaveFile {

  /**
   * @param {?Uint8Array} bytes A wave file buffer.
   * @throws {Error} If no 'RIFF' chunk is found.
   * @throws {Error} If no 'fmt ' chunk is found.
   * @throws {Error} If no 'data' chunk is found.
   */
  constructor(bytes=null) {
    /**
     * The container identifier.
     * 'RIFF', 'RIFX' and 'RF64' are supported.
     * @type {string}
     */
    this.container = '';
    /**
     * @type {number}
     */
    this.chunkSize = 0;
    /**
     * The format.
     * Always 'WAVE'.
     * @type {string}
     */
    this.format = '';
    /**
     * The data of the 'fmt' chunk.
     * @type {!Object<string, *>}
     */
    this.fmt = {
      /** @type {string} */
      chunkId: '',
      /** @type {number} */
      chunkSize: 0,
      /** @type {number} */
      audioFormat: 0,
      /** @type {number} */
      numChannels: 0,
      /** @type {number} */
      sampleRate: 0,
      /** @type {number} */
      byteRate: 0,
      /** @type {number} */
      blockAlign: 0,
      /** @type {number} */
      bitsPerSample: 0,
      /** @type {number} */
      cbSize: 0,
      /** @type {number} */
      validBitsPerSample: 0,
      /** @type {number} */
      dwChannelMask: 0,
      /**
       * 4 32-bit values representing a 128-bit ID
       * @type {!Array<number>}
       */
      subformat: []
    };
    /**
     * The data of the 'fact' chunk.
     * @type {!Object<string, *>}
     */
    this.fact = {
      /** @type {string} */
      chunkId: '',
      /** @type {number} */
      chunkSize: 0,
      /** @type {number} */
      dwSampleLength: 0
    };
    /**
     * The data of the 'cue ' chunk.
     * @type {!Object<string, *>}
     */
    this.cue = {
      /** @type {string} */
      chunkId: '',
      /** @type {number} */
      chunkSize: 0,
      /** @type {number} */
      dwCuePoints: 0,
      /** @type {!Array<!Object>} */
      points: [],
    };
    /**
     * The data of the 'smpl' chunk.
     * @type {!Object<string, *>}
     */
    this.smpl = {
      /** @type {string} */
      chunkId: '',
      /** @type {number} */
      chunkSize: 0,
      /** @type {number} */
      dwManufacturer: 0,
      /** @type {number} */
      dwProduct: 0,
      /** @type {number} */
      dwSamplePeriod: 0,
      /** @type {number} */
      dwMIDIUnityNote: 0,
      /** @type {number} */
      dwMIDIPitchFraction: 0,
      /** @type {number} */
      dwSMPTEFormat: 0,
      /** @type {number} */
      dwSMPTEOffset: 0,
      /** @type {number} */
      dwNumSampleLoops: 0,
      /** @type {number} */
      dwSamplerData: 0,
      /** @type {!Array<!Object>} */
      loops: []
    };
    /**
     * The data of the 'bext' chunk.
     * @type {!Object<string, *>}
     */
    this.bext = {
      /** @type {string} */
      chunkId: '',
      /** @type {number} */
      chunkSize: 0,
      /** @type {string} */
      description: '', //256
      /** @type {string} */
      originator: '', //32
      /** @type {string} */
      originatorReference: '', //32
      /** @type {string} */
      originationDate: '', //10
      /** @type {string} */
      originationTime: '', //8
      /**
       * 2 32-bit values, timeReference high and low
       * @type {!Array<number>}
       */
      timeReference: [0, 0],
      /** @type {number} */
      version: 0, //WORD
      /** @type {string} */
      UMID: '', // 64 chars
      /** @type {number} */
      loudnessValue: 0, //WORD
      /** @type {number} */
      loudnessRange: 0, //WORD
      /** @type {number} */
      maxTruePeakLevel: 0, //WORD
      /** @type {number} */
      maxMomentaryLoudness: 0, //WORD
      /** @type {number} */
      maxShortTermLoudness: 0, //WORD
      /** @type {string} */
      reserved: '', //180
      /** @type {string} */
      codingHistory: '' // string, unlimited
    };
    /**
     * The data of the 'ds64' chunk.
     * Used only with RF64 files.
     * @type {!Object<string, *>}
     */
    this.ds64 = {
      /** @type {string} */
      chunkId: '',
      /** @type {number} */
      chunkSize: 0,
      /** @type {number} */
      riffSizeHigh: 0, // DWORD
      /** @type {number} */
      riffSizeLow: 0, // DWORD
      /** @type {number} */
      dataSizeHigh: 0, // DWORD
      /** @type {number} */
      dataSizeLow: 0, // DWORD
      /** @type {number} */
      originationTime: 0, // DWORD
      /** @type {number} */
      sampleCountHigh: 0, // DWORD
      /** @type {number} */
      sampleCountLow: 0 // DWORD
      /** @type {number} */
      //'tableLength': 0, // DWORD
      /** @type {!Array<number>} */
      //'table': []
    };
    /**
     * The data of the 'data' chunk.
     * @type {!Object<string, *>}
     */
    this.data = {
      /** @type {string} */
      chunkId: '',
      /** @type {number} */
      chunkSize: 0,
      /** @type {!Uint8Array} */
      samples: new Uint8Array(0)
    };
    /**
     * The data of the 'LIST' chunks.
     * Each item in this list look like this:
     *  {
     *      chunkId: '',
     *      chunkSize: 0,
     *      format: '',
     *      subChunks: []
     *   }
     * @type {!Array<!Object>}
     */
    this.LIST = [];
    /**
     * The data of the 'junk' chunk.
     * @type {!Object<string, *>}
     */
    this.junk = {
      /** @type {string} */
      chunkId: '',
      /** @type {number} */
      chunkSize: 0,
      /** @type {!Array<number>} */
      chunkData: []
    };
    /**
     * @type {!Object}
     * @private
     */
    this.uInt16_ = {bits: 16, be: false};
    /**
     * @type {!Object}
     * @private
     */
    this.uInt32_ = {bits: 32, be: false};
    /**
     * The bit depth code according to the samples.
     * @type {string}
     */
    this.bitDepth = '0';
    /**
     * @type {!Object}
     * @private
     */
    this.dataType = {};
    this.io = new BufferIO();
    // Load a file from the buffer if one was passed
    // when creating the object
    if(bytes) {
      this.fromBuffer(bytes);
    }
  }

  /**
   * Set up the WaveFile object based on the arguments passed.
   * @param {number} numChannels The number of channels
   *    (Integer numbers: 1 for mono, 2 stereo and so on).
   * @param {number} sampleRate The sample rate.
   *    Integer numbers like 8000, 44100, 48000, 96000, 192000.
   * @param {string} bitDepthCode The audio bit depth code.
   *    One of '4', '8', '8a', '8m', '16', '24', '32', '32f', '64'
   *    or any value between '8' and '32' (like '12').
   * @param {!Array<number>|!Array<!Array<number>>|!ArrayBufferView} samples
   *    The samples. Must be in the correct range according to the bit depth.
   * @param {?Object} options Optional. Used to force the container
   *    as RIFX with {'container': 'RIFX'}
   * @throws {Error} If any argument does not meet the criteria.
   */
  fromScratch(numChannels, sampleRate, bitDepthCode, samples, options={}) {
    if (!options.container) {
      options.container = 'RIFF';
    }
    this.container = options.container;
    this.bitDepth = bitDepthCode;
    samples = this.interleave_(samples);
    this.updateDataType_();
    /** @type {number} */
    let numBytes = this.dataType.bits / 8;
    this.data.samples = new Uint8Array(samples.length * numBytes);
    packArrayTo(samples, this.dataType, this.data.samples);
    /** @type {!Object} */
    let header = wavHeader(
      bitDepthCode, numChannels, sampleRate,
      numBytes, this.data.samples.length, options);
    this.clearHeader_();
    this.chunkSize = header.chunkSize;
    this.format = header.format;
    this.fmt = header.fmt;
    if (header.fact) {
      this.fact = header.fact;
    }
    this.data.chunkId = 'data';
    this.data.chunkSize = this.data.samples.length;
    validateHeader_(this);
    this.LEorBE_();
  }

  /**
   * Reset attributes that should emptied when a file is
   * created with the fromScratch() or fromBuffer() methods.
   * @private
   */
  clearHeader_() {
    this.fmt.cbSize = 0;
    this.fmt.validBitsPerSample = 0;
    this.fact.chunkId = '';
    this.ds64.chunkId = '';
  }

  /**
   * Set up the WaveFile object from a byte buffer.
   * @param {!Uint8Array} bytes The buffer.
   * @param {boolean=} samples True if the samples should be loaded.
   * @throws {Error} If container is not RIFF, RIFX or RF64.
   * @throws {Error} If no 'fmt ' chunk is found.
   * @throws {Error} If no 'data' chunk is found.
   */
  fromBuffer(bytes, samples=true) {
    this.clearHeader_();
    readWavBuffer(bytes, samples, this, this.uInt32_, this.uInt16_);
    this.updateDataType_();
  }

  /**
   * Return a byte buffer representig the WaveFile object as a .wav file.
   * The return value of this method can be written straight to disk.
   * @return {!Uint8Array} A .wav file.
   * @throws {Error} If any property of the object appears invalid.
   */
  toBuffer() {
    validateHeader_(this);
    return writeWavBuffer(this, this.uInt32_, this.uInt16_);
  }

  /**
   * Use a .wav file encoded as a base64 string to load the WaveFile object.
   * @param {string} base64String A .wav file as a base64 string.
   * @throws {Error} If any property of the object appears invalid.
   */
  fromBase64(base64String) {
    this.fromBuffer(new Uint8Array(decode(base64String)));
  }

  /**
   * Return a base64 string representig the WaveFile object as a .wav file.
   * @return {string} A .wav file as a base64 string.
   * @throws {Error} If any property of the object appears invalid.
   */
  toBase64() {
    /** @type {!Uint8Array} */
    let buffer = this.toBuffer();
    return encode(buffer, 0, buffer.length);
  }

  /**
   * Return a DataURI string representig the WaveFile object as a .wav file.
   * The return of this method can be used to load the audio in browsers.
   * @return {string} A .wav file as a DataURI.
   * @throws {Error} If any property of the object appears invalid.
   */
  toDataURI() {
    return 'data:audio/wav;base64,' + this.toBase64();
  }

  /**
   * Use a .wav file encoded as a DataURI to load the WaveFile object.
   * @param {string} dataURI A .wav file as DataURI.
   * @throws {Error} If any property of the object appears invalid.
   */
  fromDataURI(dataURI) {
    this.fromBase64(dataURI.replace('data:audio/wav;base64,', ''));
  }

  /**
   * Force a file as RIFF.
   */
  toRIFF() {
    if (this.container == 'RF64') {
      this.fromScratch(
        this.fmt.numChannels,
        this.fmt.sampleRate,
        this.bitDepth,
        unpackArray(this.data.samples, this.dataType));
    } else {
      this.dataType.be = true;
      this.fromScratch(
        this.fmt.numChannels,
        this.fmt.sampleRate,
        this.bitDepth,
        unpackArray(this.data.samples, this.dataType));
    }
  }

  /**
   * Force a file as RIFX.
   */
  toRIFX() {
    if (this.container == 'RF64') {
      this.fromScratch(
        this.fmt.numChannels,
        this.fmt.sampleRate,
        this.bitDepth,
        unpackArray(this.data.samples, this.dataType),
        {container: 'RIFX'});
    } else {
      this.fromScratch(
        this.fmt.numChannels,
        this.fmt.sampleRate,
        this.bitDepth,
        unpackArray(this.data.samples, this.dataType),
        {container: 'RIFX'});
    }
  }

  /**
   * Change the bit depth of the samples.
   * @param {string} newBitDepth The new bit depth of the samples.
   *    One of '8' ... '32' (integers), '32f' or '64' (floats)
   * @param {boolean} changeResolution A boolean indicating if the
   *    resolution of samples should be actually changed or not.
   * @throws {Error} If the bit depth is not valid.
   */
  toBitDepth(newBitDepth, changeResolution=true) {
    /** @type {string} */
    let toBitDepth = newBitDepth;
    /** @type {string} */
    let thisBitDepth = this.bitDepth;
    if (!changeResolution) {
      if (newBitDepth != '32f') {
        toBitDepth = this.dataType.bits.toString();
      }
      thisBitDepth = this.dataType.bits;
    }
    this.assureUncompressed_();
    /** @type {number} */
    let sampleCount = this.data.samples.length / (this.dataType.bits / 8);
    /** @type {!Float64Array} */
    let typedSamplesInput = new Float64Array(sampleCount + 1);
    /** @type {!Float64Array} */
    let typedSamplesOutput = new Float64Array(sampleCount + 1);
    unpackArrayTo(this.data.samples, this.dataType, typedSamplesInput);
    bitDepthLib(
      typedSamplesInput, thisBitDepth, toBitDepth, typedSamplesOutput);
    this.fromScratch(
      this.fmt.numChannels,
      this.fmt.sampleRate,
      newBitDepth,
      typedSamplesOutput,
      {container: this.correctContainer_()});
  }

  /**
   * Encode a 16-bit wave file as 4-bit IMA ADPCM.
   * @throws {Error} If sample rate is not 8000.
   * @throws {Error} If number of channels is not 1.
   */
  toIMAADPCM() {
    if (this.fmt.sampleRate !== 8000) {
      throw new Error(
        'Only 8000 Hz files can be compressed as IMA-ADPCM.');
    } else if(this.fmt.numChannels !== 1) {
      throw new Error(
        'Only mono files can be compressed as IMA-ADPCM.');
    } else {
      this.assure16Bit_();
      let output = new Int16Array(this.data.samples.length / 2);
      unpackArrayTo(this.data.samples, this.dataType, output);
      this.fromScratch(
        this.fmt.numChannels,
        this.fmt.sampleRate,
        '4',
        imaadpcm.encode(output),
        {container: this.correctContainer_()});
    }
  }

  /**
   * Decode a 4-bit IMA ADPCM wave file as a 16-bit wave file.
   * @param {string} bitDepthCode The new bit depth of the samples.
   *    One of '8' ... '32' (integers), '32f' or '64' (floats).
   *    Optional. Default is 16.
   */
  fromIMAADPCM(bitDepthCode='16') {
    this.fromScratch(
      this.fmt.numChannels,
      this.fmt.sampleRate,
      '16',
      imaadpcm.decode(this.data.samples, this.fmt.blockAlign),
      {container: this.correctContainer_()});
    if (bitDepthCode != '16') {
      this.toBitDepth(bitDepthCode);
    }
  }

  /**
   * Encode a 16-bit wave file as 8-bit A-Law.
   */
  toALaw() {
    this.assure16Bit_();
    let output = new Int16Array(this.data.samples.length / 2);
    unpackArrayTo(this.data.samples, this.dataType, output);
    this.fromScratch(
      this.fmt.numChannels,
      this.fmt.sampleRate,
      '8a',
      alawmulaw.alaw.encode(output),
      {container: this.correctContainer_()});
  }

  /**
   * Decode a 8-bit A-Law wave file into a 16-bit wave file.
   * @param {string} bitDepthCode The new bit depth of the samples.
   *    One of '8' ... '32' (integers), '32f' or '64' (floats).
   *    Optional. Default is 16.
   */
  fromALaw(bitDepthCode='16') {
    this.fromScratch(
      this.fmt.numChannels,
      this.fmt.sampleRate,
      '16',
      alawmulaw.alaw.decode(this.data.samples),
      {container: this.correctContainer_()});
    if (bitDepthCode != '16') {
      this.toBitDepth(bitDepthCode);
    }
  }

  /**
   * Encode 16-bit wave file as 8-bit mu-Law.
   */
  toMuLaw() {
    this.assure16Bit_();
    let output = new Int16Array(this.data.samples.length / 2);
    unpackArrayTo(this.data.samples, this.dataType, output);
    this.fromScratch(
      this.fmt.numChannels,
      this.fmt.sampleRate,
      '8m',
      alawmulaw.mulaw.encode(output),
      {container: this.correctContainer_()});
  }

  /**
   * Decode a 8-bit mu-Law wave file into a 16-bit wave file.
   * @param {string} bitDepthCode The new bit depth of the samples.
   *    One of '8' ... '32' (integers), '32f' or '64' (floats).
   *    Optional. Default is 16.
   */
  fromMuLaw(bitDepthCode='16') {
    this.fromScratch(
      this.fmt.numChannels,
      this.fmt.sampleRate,
      '16',
      alawmulaw.mulaw.decode(this.data.samples),
      {container: this.correctContainer_()});
    if (bitDepthCode != '16') {
      this.toBitDepth(bitDepthCode);
    }
  }

  /**
   * 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 = this.fixTagName_(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});
    }
  }

  /**
   * 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;
  }

  /**
   * Remove a RIFF tag in 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;
  }

  /**
   * Create a cue point in the wave file.
   * @param {number} position The cue point position in milliseconds.
   * @param {string} labl The LIST adtl labl text of the marker. Optional.
   */
  setCuePoint(position, labl='') {
    this.cue.chunkId = 'cue ';
    position = (position * this.fmt.sampleRate) / 1000;
    /** @type {!Array<!Object>} */
    let existingPoints = this.getCuePoints_();
    this.clearLISTadtl_();
    /** @type {number} */
    let len = this.cue.points.length;
    this.cue.points = [];
    /** @type {boolean} */
    let hasSet = false;
    if (len === 0) {
      this.setCuePoint_(position, 1, labl);
    } else {
      for (let i=0; i<len; i++) {
        if (existingPoints[i].dwPosition > position && !hasSet) {
          this.setCuePoint_(position, i + 1, labl);
          this.setCuePoint_(
            existingPoints[i].dwPosition,
            i + 2,
            existingPoints[i].label);
          hasSet = true;
        } else {
          this.setCuePoint_(
            existingPoints[i].dwPosition,
            i + 1,
            existingPoints[i].label);
        }
      }
      if (!hasSet) {
        this.setCuePoint_(position, this.cue.points.length + 1, labl);
      }
    }
    this.cue.dwCuePoints = this.cue.points.length;
  }

  /**
   * Remove a cue point from a wave file.
   * @param {number} index the index of the point. First is 1,
   *    second is 2, and so on.
   */
  deleteCuePoint(index) {
    this.cue.chunkId = 'cue ';
    /** @type {!Array<!Object>} */
    let existingPoints = this.getCuePoints_();
    this.clearLISTadtl_();
    /** @type {number} */
    let len = this.cue.points.length;
    this.cue.points = [];
    for (let i=0; i<len; i++) {
      if (i + 1 !== index) {
        this.setCuePoint_(
          existingPoints[i].dwPosition,
          i + 1,
          existingPoints[i].label);
      }
    }
    this.cue.dwCuePoints = this.cue.points.length;
    if (this.cue.dwCuePoints) {
      this.cue.chunkId = 'cue ';
    } else {
      this.cue.chunkId = '';
      this.clearLISTadtl_();
    }
  }

  /**
   * Update the label of a cue point.
   * @param {number} pointIndex The ID of the cue point.
   * @param {string} label The new text for the label.
   */
  updateLabel(pointIndex, label) {
    /** @type {?number} */
    let adtlIndex = this.getAdtlChunk_();
    if (adtlIndex !== null) {
      for (let i=0; i<this.LIST[adtlIndex].subChunks.length; i++) {
        if (this.LIST[adtlIndex].subChunks[i].dwName ==
            pointIndex) {
          this.LIST[adtlIndex].subChunks[i].value = label;
        }
      }
    }
  }

  /**
   * Make the file 16-bit if it is not.
   * @private
   */
  assure16Bit_() {
    this.assureUncompressed_();
    if (this.bitDepth != '16') {
      this.toBitDepth('16');
    }
  }

  /**
   * Uncompress the samples in case of a compressed file.
   * @private
   */
  assureUncompressed_() {
    if (this.bitDepth == '8a') {
      this.fromALaw();
    } else if(this.bitDepth == '8m') {
      this.fromMuLaw();
    } else if (this.bitDepth == '4') {
      this.fromIMAADPCM();
    }
  }

  /**
   * Set up the WaveFile object from a byte buffer.
   * @param {!Array<number>|!Array<!Array<number>>|!ArrayBufferView} samples The samples.
   * @private
   */
  interleave_(samples) {
    if (samples.length > 0) {
      if (samples[0].constructor === Array) {
        /** @type {!Array<number>} */
        let finalSamples = [];
        for (let i=0; i < samples[0].length; i++) {
          for (let j=0; j < samples.length; j++) {
            finalSamples.push(samples[j][i]);
          }
        }
        samples = finalSamples;
      }
    }
    return samples;
  }

  /**
   * Push a new cue point in this.cue.points.
   * @param {number} position The position in milliseconds.
   * @param {number} dwName the dwName of the cue point
   * @private
   */
  setCuePoint_(position, dwName, label) {
    this.cue.points.push({
      dwName: dwName,
      dwPosition: position,
      fccChunk: 'data',
      dwChunkStart: 0,
      dwBlockStart: 0,
      dwSampleOffset: position,
    });
    this.setLabl_(dwName, label);
  }

  /**
   * Return an array with the position of all cue points in the file.
   * @return {!Array<!Object>}
   * @private
   */
  getCuePoints_() {
    /** @type {!Array<!Object>} */
    let points = [];
    for (let i=0; i<this.cue.points.length; i++) {
      points.push({
        dwPosition: this.cue.points[i].dwPosition,
        label: this.getLabelForCuePoint_(
          this.cue.points[i].dwName)});
    }
    return points;
  }

  /**
   * Return the label of a cue point.
   * @param {number} pointDwName The ID of the cue point.
   * @return {string}
   * @private
   */
  getLabelForCuePoint_(pointDwName) {
    /** @type {?number} */
    let adtlIndex = this.getAdtlChunk_();
    if (adtlIndex !== null) {
      for (let i=0; i<this.LIST[adtlIndex].subChunks.length; i++) {
        if (this.LIST[adtlIndex].subChunks[i].dwName ==
            pointDwName) {
          return this.LIST[adtlIndex].subChunks[i].value;
        }
      }
    }
    return '';
  }

  /**
   * Clear any LIST chunk labeled as 'adtl'.
   * @private
   */
  clearLISTadtl_() {
    for (let i=0; i<this.LIST.length; i++) {
      if (this.LIST[i].format == 'adtl') {
        this.LIST.splice(i);
      }
    }
  }

  /**
   * Create a new 'labl' subchunk in a 'LIST' chunk of type 'adtl'.
   * @param {number} dwName The ID of the cue point.
   * @param {string} label The label for the cue point.
   * @private
   */
  setLabl_(dwName, label) {
    /** @type {?number} */
    let adtlIndex = this.getAdtlChunk_();
    if (adtlIndex === null) {
      this.LIST.push({
        chunkId: 'LIST',
        chunkSize: 4,
        format: 'adtl',
        subChunks: []});
      adtlIndex = this.LIST.length - 1;
    }
    this.setLabelText_(adtlIndex === null ? 0 : adtlIndex, dwName, label);
  }

  /**
   * Create a new 'labl' subchunk in a 'LIST' chunk of type 'adtl'.
   * @param {number} adtlIndex The index of the 'adtl' LIST in this.LIST.
   * @param {number} dwName The ID of the cue point.
   * @param {string} label The label for the cue point.
   * @private
   */
  setLabelText_(adtlIndex, dwName, label) {
    this.LIST[adtlIndex].subChunks.push({
      chunkId: 'labl',
      chunkSize: label.length,
      dwName: dwName,
      value: label
    });
    this.LIST[adtlIndex].chunkSize += label.length + 4 + 4 + 4 + 1;
  }

  /**
   * Return the index of the 'adtl' LIST in this.LIST.
   * @return {?number}
   * @private
   */
  getAdtlChunk_() {
    for (let i=0; i<this.LIST.length; i++) {
      if(this.LIST[i].format == 'adtl') {
        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; i<this.LIST.length; i++) {
      if (this.LIST[i].format == 'INFO') {
        index.LIST = i;
        for (let j=0; j<this.LIST[i].subChunks.length; 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
   */
  fixTagName_(tag) {
    if (tag.constructor !== String) {
      throw new Error('Invalid tag name.');
    } else if(tag.length < 4) {
      for (let i=0; i<4-tag.length; i++) {
        tag += ' ';
      }
    }
    return tag;
  }

  /**
   * Set up to work wih big-endian or little-endian files.
   * The types used are changed to LE or BE. If the
   * the file is big-endian (RIFX), true is returned.
   * @return {boolean} True if the file is RIFX.
   * @private
   */
  LEorBE_() {
    /** @type {boolean} */
    let bigEndian = this.container === 'RIFX';
    this.uInt16_.be = bigEndian;
    this.uInt32_.be = bigEndian;
    return bigEndian;
  }

  /**
   * Update the type definition used to read and write the samples.
   * @private
   */
  updateDataType_() {
    /** @type {!Object} */
    this.dataType = {
      bits: ((parseInt(this.bitDepth, 10) - 1) | 7) + 1,
      float: this.bitDepth == '32f' || this.bitDepth == '64',
      signed: this.bitDepth != '8',
      be: this.container == 'RIFX'
    };
    if (['4', '8a', '8m'].indexOf(this.bitDepth) > -1 ) {
      this.dataType.bits = 8;
      this.dataType.signed = false;
    }
  }

  /**
   * Return 'RIFF' if the container is 'RF64', the current container name
   * otherwise. Used to enforce 'RIFF' when RF64 is not allowed.
   * @return {string}
   * @private
   */
  correctContainer_() {
    return this.container == 'RF64' ? 'RIFF' : this.container;
  }
}