constructor(length, channelCount) {
    this._readIndex = 0;
    this._writeIndex = 0;
    this._framesAvailable = 0;

    this._channelCount = channelCount;
    this._length = length;
    this._channelData = [];
    for (let i = 0; i < this._channelCount; ++i) {
      this._channelData[i] = new Float32Array(length);
    }
  }
@constructor
@param  {number} length Buffer length in frames.
@param  {number} channelCount Buffer channel count.