PhoenixSubtitle

using Nikse.SubtitleEdit.Core.Common;
using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;

namespace Nikse.SubtitleEdit.Core.SubtitleFormats
{
    /// <summary>
    /// Implements https://web.archive.org/web/20080213213927/http://trac.annodex.net/wiki/PJS
    /// https://github.com/SubtitleEdit/subtitleedit/pull/1964#issuecomment-249379407
    /// </summary>
    public class PhoenixSubtitle : SubtitleFormat
    {
        //2447,   2513, "You should come to the Drama Club, too."
        //2513,   2594, "Yeah. The Drama Club is worried|that you haven't been coming."
        //2603,   2675, "I see. Sorry, I'll drop by next time."

        private static readonly Regex RegexTimeCodes = new Regex(@"^(\d+),\s*(\d+),", RegexOptions.Compiled);
        private static readonly char[] TrimChars = { ' ', '"' };

        public override string Extension => ".pjs";

        public override bool IsTimeBased => false;

        public override string Name => "Phoenix Subtitle";

        public override bool IsMine(List<string> lines, string fileName)
        {
            if (fileName?.EndsWith(".pjs", StringComparison.OrdinalIgnoreCase) == false)
            {
                return false;
            }
            return base.IsMine(lines, fileName);
        }

        private Paragraph ToParagraph(string line) => StartTime(line, 0);

        // 5710,5754,"There isn't anything|in sector 14."
        private Paragraph StartTime(string line, int index)
        {
            // 3144,3217,"Alien VS. Predator"
            var ch = line[index];
            int from = index;
            if (!char.IsDigit(ch)) return null;
            while (char.IsDigit(line[index])) index++;
            return EndTime(int.Parse(line.Substring(from, index - from)), line, index);
        }

        private Paragraph EndTime(int startTime, string line, int index)
        {
            var ch = line[index];
            if (ch != ',') return null;
            index++;

            while(char.IsWhiteSpace(line[index])) index++;

            int from = index;

            while (index < line.Length && char.IsDigit(line[index])) index++;
            if(index == line.Length) return null;

            return Text(startTime, int.Parse(line.Substring(from, index - from)), line, index);
        }

        private Paragraph Text(int startTime, int endTime, string line, int index)
        {
            // skip:,"
            if (line[index] == ',') index++;
            if (line[index] == '"') index++;
            int len = line.Length;
            if (line.Length - 1 > 0 && line[len - 1] == '"') len--;
            var text = string.Join(Environment.NewLine, line.Substring(index, len - index).Split('|'));
            return new Paragraph(text, FramesToMilliseconds(startTime), FramesToMilliseconds(endTime));
        }

        public override void LoadSubtitle(Subtitle subtitle, List<string> lines, string fileName)
        {
            subtitle.Paragraphs.Clear();
            _errorCount = 0;
            for (var i = 0; i < lines.Count; i++)
            {
                string line = lines[i].Trim();

                // too short line
                if (line.Length < 4)
                {
                    _errorCount++;
                    continue;
                }

                var paragraph = ToParagraph(line);
                if (paragraph != null)
                {
                    subtitle.Paragraphs.Add(paragraph);
                }
                else
                {
                    _errorCount++;
                }
            }
        }

        public override string ToText(Subtitle subtitle, string title)
        {
            const string writeFormat = "{0},{1},\"{2}\"{3}";
            var sb = new StringBuilder();
            foreach (var p in subtitle.Paragraphs)
            {
                string text = HtmlUtil.RemoveHtmlTags(p.Text, true);
                // Pipe character for forced line breaks.
                text = text.Replace(Environment.NewLine, "|");
                sb.AppendFormat(writeFormat, MillisecondsToFrames(p.StartTime.TotalMilliseconds), MillisecondsToFrames(p.EndTime.TotalMilliseconds), text, Environment.NewLine);
            }
            return sb.ToString();
        }

    }
}

https://github.com/SubtitleEdit/subtitleedit/blob/1ee22c8f6b95402286bbec47bf1fd70a1d5812d7/src/libse/SubtitleFormats/PhoenixSubtitle.cs