const x0 = Math.round(n * .3);

        const x1 = Math.round(n * .6);

        const pt0 = this.songToVideo[x0];

        const pt1 = this.songToVideo[x1];

        return (pt1[1] - pt0[1]) / (pt1[0] - pt0[0]);

    }

    setVideoTimeFromSongTime(songTime, isPlaying) {

        if (!this.songToVideo || !this.outVideo || this.outVideo.readyState < 1) {

            return;

        }

        const i = _.sortedIndex(this.songToVideo, [songTime],

                                (row) => { return row[0]; });

        this.videoTime = this.songToVideo[Math.max(0, i - 1)][1];

        this.outVideoCurrentTime = this.outVideo.currentTime;

        if (isPlaying) {

            if (this.outVideo.paused) {

                this.outVideo.play();

                this.setRate(this.estimateRate());

            }

            const err = this.outVideo.currentTime - this.videoTime;

            this.timeErr = err;