使用javascript / jquery

Question

在我的项目中，我需要添加一个时间码（偏移量）和另一个时间码（原始码），以便在自定义的html5视频播放器中显示。

00:00:17.16 --->(original timecode) +
07:49:42.08 --->(offset timecode)
-----------
07:49:59:24   sincle framerate is 23, this time code is rounded to
07:49:60:01 (7 hrs : 49 mins :60 secs and 1 frame) which is equal to
07:50:00:01 ------>(Resultant timecode)
===========

这很容易，我在javascript中为它编写了som代码。

function AddTimeCodeWithOffset(Offset, Original, framerate) {
    var newTime = Original;
    var framerate = parseFloat(framerate);
    if (Offset != '00:00:00:00') {
        var arOff = Offset.split(':');
        var arOrg = Original.split(':');
        var hour = parseInt(arOff[0]) + parseInt(arOrg[0]);
        var minute = parseInt(arOff[1]) + parseInt(arOrg[1]);
        var second = parseInt(arOff[2]) + parseInt(arOrg[2]);
        var frame = parseInt(arOff[3]) + parseInt(arOrg[3]);
        if (frame >= framerate) {
            frame = Math.round(frame - framerate);
            second = second + 1;
        }
        if (second >= 60) {
            second = second - 60;
            minute = minute + 1;
        }
        if (minute >= 60) {
            minute = minute - 60;
            hour = hour + 1;
        }
        if (frame < 10) { frame = '0' + frame.toString(); }
        if (second < 10) { second = '0' + second.toString(); }
        if (minute < 10) { minute = '0' + minute.toString(); }
        if (hour < 10) { hour = '0' + hour.toString(); }
        newTime = hour + ':' + minute + ':' + second + ':' + frame;
    }
    return newTime;
}

但如何执行相反的处理。要通过减去original time code

从resultant time code获取offset time code