resetFromJSON(o) {
        this.tracks = [];
        this.tickPeriod = 0;
        this.beatPeriod = 0;

        // -status-
        this.IsPlaying = false;
        this.playingTrackCnt = 0;
        return this;
    }
Reset status by JSON object
@param {object} o JSON object
@returns {object} this object