jellyfin/MediaBrowser.MediaEncoding/Subtitles/SrtParser.cs
Bond_009 febb6bced6 Review usage of string.Substring (part 1)
Reduced allocations by replacing string.Substring with ReadOnlySpan<char>.Slice
2020-07-22 13:39:24 +02:00

103 lines
3.9 KiB
C#

#pragma warning disable CS1591
using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Text.RegularExpressions;
using System.Threading;
using MediaBrowser.Model.MediaInfo;
using Microsoft.Extensions.Logging;
namespace MediaBrowser.MediaEncoding.Subtitles
{
public class SrtParser : ISubtitleParser
{
private readonly ILogger _logger;
private readonly CultureInfo _usCulture = new CultureInfo("en-US");
public SrtParser(ILogger logger)
{
_logger = logger;
}
/// <inheritdoc />
public SubtitleTrackInfo Parse(Stream stream, CancellationToken cancellationToken)
{
var trackInfo = new SubtitleTrackInfo();
var trackEvents = new List<SubtitleTrackEvent>();
using (var reader = new StreamReader(stream))
{
string line;
while ((line = reader.ReadLine()) != null)
{
cancellationToken.ThrowIfCancellationRequested();
if (string.IsNullOrWhiteSpace(line))
{
continue;
}
var subEvent = new SubtitleTrackEvent { Id = line };
line = reader.ReadLine();
if (string.IsNullOrWhiteSpace(line))
{
continue;
}
var time = Regex.Split(line, @"[\t ]*-->[\t ]*");
if (time.Length < 2)
{
// This occurs when subtitle text has an empty line as part of the text.
// Need to adjust the break statement below to resolve this.
_logger.LogWarning("Unrecognized line in srt: {0}", line);
continue;
}
subEvent.StartPositionTicks = GetTicks(time[0]);
var endTime = time[1].AsSpan();
var idx = endTime.IndexOf(' ');
if (idx > 0)
{
endTime = endTime.Slice(0, idx);
}
subEvent.EndPositionTicks = GetTicks(endTime);
var multiline = new List<string>();
while ((line = reader.ReadLine()) != null)
{
if (string.IsNullOrEmpty(line))
{
break;
}
multiline.Add(line);
}
subEvent.Text = string.Join(ParserValues.NewLine, multiline);
subEvent.Text = subEvent.Text.Replace(@"\N", ParserValues.NewLine, StringComparison.OrdinalIgnoreCase);
subEvent.Text = Regex.Replace(subEvent.Text, @"\{(?:\\\d?[\w.-]+(?:\([^\)]*\)|&H?[0-9A-Fa-f]+&|))+\}", string.Empty, RegexOptions.IgnoreCase);
subEvent.Text = Regex.Replace(subEvent.Text, "<", "&lt;", RegexOptions.IgnoreCase);
subEvent.Text = Regex.Replace(subEvent.Text, ">", "&gt;", RegexOptions.IgnoreCase);
subEvent.Text = Regex.Replace(subEvent.Text, "&lt;(\\/?(font|b|u|i|s))((\\s+(\\w|\\w[\\w\\-]*\\w)(\\s*=\\s*(?:\\\".*?\\\"|'.*?'|[^'\\\">\\s]+))?)+\\s*|\\s*)(\\/?)&gt;", "<$1$3$7>", RegexOptions.IgnoreCase);
trackEvents.Add(subEvent);
}
}
trackInfo.TrackEvents = trackEvents.ToArray();
return trackInfo;
}
private long GetTicks(ReadOnlySpan<char> time)
{
return TimeSpan.TryParseExact(time, @"hh\:mm\:ss\.fff", _usCulture, out var span)
? span.Ticks
: (TimeSpan.TryParseExact(time, @"hh\:mm\:ss\,fff", _usCulture, out span)
? span.Ticks : 0);
}
}
}