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

    namespace Nikse.SubtitleEdit.Core.SubtitleFormats
    {
        public class UnknownSubtitle56 : SubtitleFormat
        {
            //0001  01:00:37:22 01:00:39:11
            private static readonly Regex RegexTimeCodes1 = new Regex(@"^\d\d\d\d\t\d\d:\d\d:\d\d:\d\d\t\d\d:\d\d:\d\d:\d\d$", RegexOptions.Compiled);

            public override string Extension => ".txt";

            public override string Name => "Unknown 56";

            public override string ToText(Subtitle subtitle, string title)
            {
                var sb = new StringBuilder();
                const string format = "{0:0000}\t{1}\t{2}";
                foreach (Paragraph p in subtitle.Paragraphs)
                {
                    sb.AppendLine(string.Format(format, 1, EncodeTimeCode(p.StartTime), EncodeTimeCode(p.EndTime)));
                    sb.AppendLine(HtmlUtil.RemoveHtmlTags(p.Text));
                    sb.AppendLine();
                }
                return sb.ToString();
            }

            private static string EncodeTimeCode(TimeCode time)
            {
                return $"{time.Hours:00}:{time.Minutes:00}:{time.Seconds:00}:{MillisecondsToFramesMaxFrameRate(time.Milliseconds):00}";
            }

            public override void LoadSubtitle(Subtitle subtitle, List<string> lines, string fileName)
            {
                _errorCount = 0;
                bool expectStartTime = true;
                var p = new Paragraph();
                subtitle.Paragraphs.Clear();
                char[] splitChars = { '.', ':' };
                foreach (string line in lines)
                {
                    string s = line.Trim();
                    var match = RegexTimeCodes1.Match(s);
                    if (match.Success)
                    {
                        string[] parts = s.Split('\t');
                        if (parts.Length == 3)
                        {
                            try
                            {
                                if (!string.IsNullOrEmpty(p.Text))
                                {
                                    subtitle.Paragraphs.Add(p);
                                    p = new Paragraph();
                                }
                                p.StartTime = DecodeTimeCodeFrames(parts[1], splitChars);
                                p.EndTime = DecodeTimeCodeFrames(parts[2], splitChars);
                                expectStartTime = false;
                            }
                            catch (Exception exception)
                            {
                                _errorCount++;
                                System.Diagnostics.Debug.WriteLine(exception.Message);
                            }
                        }
                    }
                    else if (string.IsNullOrWhiteSpace(line))
                    {
                        if (Math.Abs(p.StartTime.TotalMilliseconds) < 0.01 && Math.Abs(p.EndTime.TotalMilliseconds) < 0.01)
                            _errorCount++;
                        else
                            subtitle.Paragraphs.Add(p);
                        p = new Paragraph();
                    }
                    else if (!expectStartTime)
                    {
                        p.Text = (p.Text + Environment.NewLine + line).Trim();
                        if (p.Text.Length > 500)
                        {
                            _errorCount += 10;
                            return;
                        }
                        while (p.Text.Contains(Environment.NewLine + " "))
                            p.Text = p.Text.Replace(Environment.NewLine + " ", Environment.NewLine);
                    }
                }
                if (p.EndTime.TotalMilliseconds > 0)
                    subtitle.Paragraphs.Add(p);

                foreach (Paragraph temp in subtitle.Paragraphs)
                    temp.Text = temp.Text.Replace("<", "@ITALIC_START").Replace(">", "</i>").Replace("@ITALIC_START", "<i>");

                subtitle.RemoveEmptyLines();
                subtitle.Renumber();
            }

        }
    }

↑ V3095 The 'line' object was used before it was verified against null. Check lines: 44, 69.