google's video camera code explanation of a function-updateRecordingTimer..please explain..

[AndroiDev]

private void updateRecordingTime() {
if (!mMediaRecorderRecording) {
return;
}
long now = SystemClock.uptimeMillis();
long delta = now - 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_TI