    ﻿using System;
    using System.Collections.Generic;
    using System.Text;
    using System.Text.RegularExpressions;

    namespace Nikse.SubtitleEdit.Core.SubtitleFormats
    {
        public class UnknownSubtitle27 : SubtitleFormat
        {
            private static readonly Regex RegexTimeCodes = new Regex(@"^\d\d:\d\d:\d\d:  ", RegexOptions.Compiled);

            public override string Extension => ".txt";

            public override string Name => "Unknown 27";

            public override string ToText(Subtitle subtitle, string title)
            {
                var sb = new StringBuilder();
                foreach (Paragraph p in subtitle.Paragraphs)
                {
                    //00:18:02:  (斉藤)失礼な大人って！  (悠子)何言ってんのあんた？
                    string text = HtmlUtil.RemoveHtmlTags(p.Text);
                    text = text.Replace(Environment.NewLine, "  ");
                    sb.AppendLine($"{EncodeTimeCode(p.StartTime)}  {text}");
                    sb.AppendLine();
                }
                return sb.ToString();
            }

            private static string EncodeTimeCode(TimeCode time)
            {
                //00:03:15:22 (last is frame)
                int sec = time.Seconds;
                if (time.Milliseconds >= 500)
                    sec++;
                return $"{time.Hours:00}:{time.Minutes:00}:{sec:00}:";
            }

            public override void LoadSubtitle(Subtitle subtitle, List<string> lines, string fileName)
            {
                //  00:18:02:  (斉藤)失礼な大人って！  (悠子)何言ってんのあんた？
                Paragraph p = null;
                subtitle.Paragraphs.Clear();
                _errorCount = 0;
                foreach (string line in lines)
                {
                    string s = line.Trim();
                    if (RegexTimeCodes.IsMatch(s))
                    {
                        var temp = s.Substring(0, 8);

                        string[] startParts = temp.Split(SplitCharColon, StringSplitOptions.RemoveEmptyEntries);
                        if (startParts.Length == 3)
                        {
                            try
                            {
                                string text = s.Remove(0, 10).Trim();
                                text = text.Replace("  ", Environment.NewLine);
                                p = new Paragraph(DecodeTimeCode(startParts), new TimeCode(), text);
                                subtitle.Paragraphs.Add(p);
                            }
                            catch (Exception exception)
                            {
                                _errorCount++;
                                System.Diagnostics.Debug.WriteLine(exception.Message);
                            }
                        }
                    }
                    else if (string.IsNullOrWhiteSpace(line))
                    {
                        // skip empty lines
                    }
                    else if (p != null)
                    {
                        _errorCount++;
                    }
                }

                for (int i = 0; i < subtitle.Paragraphs.Count; i++)
                {
                    Paragraph current = subtitle.Paragraphs[i];
                    Paragraph next = subtitle.GetParagraphOrDefault(i + 1);
                    if (next != null)
                        current.EndTime.TotalMilliseconds = next.StartTime.TotalMilliseconds - Configuration.Settings.General.MinimumMillisecondsBetweenLines;
                    else
                        current.EndTime.TotalMilliseconds = current.StartTime.TotalMilliseconds + Utilities.GetOptimalDisplayMilliseconds(current.Text);

                    if (current.Duration.TotalMilliseconds > Configuration.Settings.General.SubtitleMaximumDisplayMilliseconds)
                        current.EndTime.TotalMilliseconds = current.StartTime.TotalMilliseconds + Configuration.Settings.General.SubtitleMaximumDisplayMilliseconds;
                }

                subtitle.Renumber();
            }

            private static TimeCode DecodeTimeCode(string[] parts)
            {
                //00:00:07:12
                string hour = parts[0];
                string minutes = parts[1];
                string seconds = parts[2];

                return new TimeCode(int.Parse(hour), int.Parse(minutes), int.Parse(seconds), 0);
            }

        }
    }

↑ V3095 The 'line' object was used before it was verified against null. Check lines: 47, 69.