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

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

            public override string Extension => ".txt";

            public override string Name => "QuickTime text";

            public override bool IsMine(List<string> lines, string fileName)
            {
                if (lines != null && lines.Count > 0 && lines[0].StartsWith("{\\rtf", StringComparison.Ordinal))
                    return false;

                var subtitle = new Subtitle();
                LoadSubtitle(subtitle, lines, fileName);
                bool isMine = subtitle.Paragraphs.Count > _errorCount;

                if (isMine && new UnknownSubtitle80().IsMine(lines, fileName))
                    return false;

                return isMine;
            }

            public override string ToText(Subtitle subtitle, string title)
            {
                const string header = @"{QTtext} {font:Tahoma}
    {plain} {size:20}
    {timeScale:30}
    {width:160} {height:32}
    {timestamps:absolute} {language:0}";

                var sb = new StringBuilder();
                sb.AppendLine(header);
                foreach (Paragraph p in subtitle.Paragraphs)
                {
                    //[00:00:07.12]
                    //d’être perdu dans un brouillard de pensées,
                    //[00:00:17.06] (this line is optional!)
                    //              (blank line optional too)
                    //[00:00:26.26]
                    //tout le temps,
                    //[00:00:35.08]
                    sb.AppendLine($"{EncodeTimeCode(p.StartTime) + Environment.NewLine}{HtmlUtil.RemoveHtmlTags(p.Text) + Environment.NewLine}{EncodeTimeCode(p.EndTime) + Environment.NewLine}");
                }
                return sb.ToString();
            }

            private static string EncodeTimeCode(TimeCode time)
            {
                //[00:00:07.12]
                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)
            {
                //[00:00:07.12]
                //d’être perdu dans un brouillard de pensées,
                //[00:00:17.06] (this line is optional!)
                //              (blank line optional too)
                //[00:00:26.26]
                //tout le temps,
                //[00:00:35.08]
                Paragraph p = null;
                subtitle.Paragraphs.Clear();
                _errorCount = 0;
                foreach (string line in lines)
                {
                    if (RegexTimeCodes.IsMatch(line))
                    {
                        string temp = line.Substring(0, RegexTimeCodes.Match(line).Length);
                        string[] parts = temp.Split(new[] { '.', ':', '[', ']' }, StringSplitOptions.RemoveEmptyEntries);
                        if (parts.Length == 4)
                        {
                            if (p == null || string.IsNullOrEmpty(p.Text))
                            {
                                try
                                {
                                    string text = string.Empty;
                                    int indexOfEndTime = line.IndexOf(']');
                                    if (indexOfEndTime > 0 && indexOfEndTime + 1 < line.Length)
                                        text = line.Substring(indexOfEndTime + 1);
                                    p = new Paragraph(DecodeTimeCodeFramesFourParts(parts), DecodeTimeCodeFramesFourParts(parts), text);
                                }
                                catch
                                {
                                    _errorCount++;
                                }
                            }
                            else
                            {
                                p.EndTime = DecodeTimeCodeFramesFourParts(parts);
                                subtitle.Paragraphs.Add(p);

                                string text = string.Empty;
                                int indexOfEndTime = line.IndexOf(']');
                                if (indexOfEndTime > 0 && indexOfEndTime + 1 < line.Length)
                                    text = line.Substring(indexOfEndTime + 1);
                                p = new Paragraph(DecodeTimeCodeFramesFourParts(parts), DecodeTimeCodeFramesFourParts(parts), text);
                            }
                        }
                    }
                    else if (string.IsNullOrWhiteSpace(line))
                    {
                        // skip these lines
                    }
                    else if (p != null)
                    {
                        if (string.IsNullOrEmpty(p.Text))
                            p.Text = line;
                        else
                            p.Text = p.Text + Environment.NewLine + line;
                    }
                    else
                    {
                        _errorCount++;
                    }
                }

                subtitle.Renumber();
            }
        }
    }

↑ V3095 The 'line' object was used before it was verified against null. Check lines: 103, 109.