SubtitleEdit: Subtitle.cs:AdjustDisplayTimeUsingMilliseconds

private void AdjustDisplayTimeUsingMilliseconds(int idx, double ms, List<double> shotChanges = null, bool enforceDurationLimits = true)
{
    var p = Paragraphs[idx];
    var nextStartTimeInMs = GetNextStartTimeInMs(idx);

    var newEndTimeInMs = p.EndTime.TotalMilliseconds + ms;
    if (enforceDurationLimits)
    {
        newEndTimeInMs = FixShortDuration(p, newEndTimeInMs);
    }

    // handle overlap with next
    newEndTimeInMs = HandleOverlapWithNext(newEndTimeInMs, nextStartTimeInMs);

    // handle shot change if supplied -- keep earliest time
    if (shotChanges != null)
    {
        newEndTimeInMs = HandleShotChange(shotChanges, newEndTimeInMs, p);
    }

    // max duration
    if (enforceDurationLimits)
    {
        newEndTimeInMs = HandleMaximumDuration(p, newEndTimeInMs);
    }

    // do not adjust wrong way
    if (!(ms > 0 && newEndTimeInMs < p.EndTime.TotalMilliseconds) && !(ms < 0 && newEndTimeInMs > p.EndTime.TotalMilliseconds))
    {
        p.EndTime.TotalMilliseconds = newEndTimeInMs;
    }
}

private double GetNextStartTimeInMs(int idx) => (idx + 1) < Paragraphs.Count ? Paragraphs[idx + 1].StartTime.TotalMilliseconds : double.MaxValue;

private double FixShortDuration(Paragraph p, double endTime)
{
    var minDur = Math.Max(Configuration.Settings.General.SubtitleMinimumDisplayMilliseconds, 100);
    return Math.Max(p.StartTime.TotalMilliseconds + minDur, endTime);
}

private double HandleOverlapWithNext(double endTime, double nextStartTime)
{
    return Math.Min(nextStartTime - Configuration.Settings.General.MinimumMillisecondsBetweenLines, endTime);
}

private double HandleShotChange(List<double> shotChanges, double endTime, Paragraph p)
{
    return Math.Min(endTime, ShotChangeHelper.GetNextShotChangeMinusGapInMs(shotChanges, p.EndTime) ?? double.MaxValue);
}

private double HandleMaximumDuration(Paragraph p, double endTime)
{
    var duration = endTime - p.StartTime.TotalMilliseconds;
    return duration > Configuration.Settings.General.SubtitleMaximumDisplayMilliseconds ? p.StartTime.TotalMilliseconds + Configuration.Settings.General.SubtitleMaximumDisplayMilliseconds : endTime;
}