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

    namespace Nikse.SubtitleEdit.Core.SubtitleFormats
    {
        public class UnknownSubtitle54 : SubtitleFormat
        {
            //10:00:31:01
            //10:00:33:02
            //This is the king's royal court.

            //10:00:33:19
            //10:00:35:00
            //This is the place,
            private static readonly Regex RegexTimeCodes1 = new Regex(@"^\d\d:\d\d:\d\d:\d\d$", RegexOptions.Compiled);

            public override string Extension => ".txt";

            public override string Name => "Unknown 54";

            public override string ToText(Subtitle subtitle, string title)
            {
                var sb = new StringBuilder();
                foreach (Paragraph p in subtitle.Paragraphs)
                {
                    sb.AppendLine(EncodeTimeCode(p.StartTime));
                    sb.AppendLine(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();
                foreach (string line in lines)
                {
                    string s = line.Trim();
                    var match = RegexTimeCodes1.Match(s);
                    if (match.Success && s.Length == 11)
                    {
                        string[] parts = s.Split(':');
                        if (parts.Length == 4)
                        {
                            try
                            {
                                if (expectStartTime)
                                {
                                    p.StartTime = DecodeTimeCodeFramesFourParts(parts);
                                    expectStartTime = false;
                                }
                                else
                                {
                                    if (p.StartTime.TotalMilliseconds < 0.01)
                                        _errorCount++;
                                    if (!string.IsNullOrEmpty(p.Text))
                                        _errorCount++;

                                    p.EndTime = DecodeTimeCodeFramesFourParts(parts);
                                }
                            }
                            catch (Exception exception)
                            {
                                _errorCount++;
                                System.Diagnostics.Debug.WriteLine(exception.Message);
                            }
                        }
                    }
                    else if (string.IsNullOrWhiteSpace(line))
                    {
                        if (Math.Abs(p.StartTime.TotalMilliseconds) < 0.001 && Math.Abs(p.EndTime.TotalMilliseconds) < 0.001)
                            _errorCount++;
                        else
                            subtitle.Paragraphs.Add(p);
                        p = new Paragraph();
                    }
                    else if (!string.IsNullOrWhiteSpace(line))
                    {
                        expectStartTime = true;
                        p.Text = (p.Text + Environment.NewLine + line).Trim();
                        if (p.Text.Length > 500)
                        {
                            _errorCount += 10;
                            return;
                        }
                    }
                }
                if (p.EndTime.TotalMilliseconds > 0)
                    subtitle.Paragraphs.Add(p);

                bool allNullEndTime = true;
                for (int i = 0; i < subtitle.Paragraphs.Count; i++)
                {
                    if (Math.Abs(subtitle.Paragraphs[i].EndTime.TotalMilliseconds) > 0.001)
                        allNullEndTime = false;
                }
                if (allNullEndTime)
                    subtitle.Paragraphs.Clear();

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

        }
    }

↑ V3022 Expression '!string.IsNullOrWhiteSpace(line)' is always true.

↑ V3095 The 'line' object was used before it was verified against null. Check lines: 49, 80.