需要帮助解释谷歌Android摄像头应用程序代码

下面的功能是谷歌相机应用程序代码的一部分。我不明白粗体字的逻辑。请帮忙。

int seconds=intent.getintextra(mediastore.extra_duration_limit,0); mmaxvideodurationinms=1000*秒;

mmediarecorder.setmaxduration(mmaxvideodurationinms);

//此函数用于更新录制时间

私有void updateRecordingTime()。{ 如果(!)我的日记顺序记录){ 返回; } long now=系统时钟.uptimemillis(); long delta=现在-mrecordingstarttime;

    // Starting a minute before reaching the max duration
    // limit, we'll countdown the remaining time instead.
    boolean countdownRemainingTime = (mMaxVideoDurationInMs != 0
            && delta >= mMaxVideoDurationInMs - 60000);

    long next_update_delay = 1000 - (delta % 1000);
    long seconds;
    if (countdownRemainingTime) {
        **delta = Math.max(0, mMaxVideoDurationInMs - delta);
        seconds = (delta + 999) / 1000;**
    } else {
        **seconds = delta / 1000; // round to nearest**
    }

    long minutes = seconds / 60;
    long hours = minutes / 60;
    long remainderMinutes = minutes - (hours * 60);
    long remainderSeconds = seconds - (minutes * 60);

    String secondsString = Long.toString(remainderSeconds);
    if (secondsString.length() < 2) {
        secondsString = "0" + secondsString;
    }
    String minutesString = Long.toString(remainderMinutes);
    if (minutesString.length() < 2) {
        minutesString = "0" + minutesString;
    }
    String text = minutesString + ":" + secondsString;
    if (hours > 0) {
        String hoursString = Long.toString(hours);
        if (hoursString.length() < 2) {
            hoursString = "0" + hoursString;
        }
        text = hoursString + ":" + text;
    }
    mRecordingTimeView.setText(text);

    if (mRecordingTimeCountsDown != countdownRemainingTime) {
        // Avoid setting the color on every update, do it only
        // when it needs changing.
        mRecordingTimeCountsDown = countdownRemainingTime;

        int color = getResources().getColor(countdownRemainingTime
                ? R.color.recording_time_remaining_text
                : R.color.recording_time_elapsed_text);

        mRecordingTimeView.setTextColor(color);
    }

    // Work around a limitation of the T-Mobile G1: The T-Mobile
    // hardware blitter can't pixel-accurately scale and clip at the
    // same time, and the SurfaceFlinger doesn't attempt to work around
    // this limitation. In order to avoid visual corruption we must
    // manually refresh the entire surface view when changing any
    // overlapping view's contents.
    mVideoPreview.invalidate();
    mHandler.sendEmptyMessageDelayed(
            UPDATE_RECORD_TIME, next_update_delay);
}