Match and mux in dropped external subtitles

Drag in subtitle files alongside .mkv files and they're matched to the right video by episode code (S04E06, zero-padding and separator insensitive, plus 4x06 as a fallback) and muxed in as extra subtitle tracks. Any subtitle format mkvmerge accepts is recognized: SRT, (S)SA, VobSub, WebVTT, PGS/SUP, USF, SAMI, TTML/DFXP, STL, Kate. Matching works regardless of drop order — subtitles dropped before their video are held pending until a matching video shows up, and vice versa. Language, forced, and SDH flags are guessed from common filename tokens (e.g. "eng", "forced", "sdh") to set the muxed track's language/name/flags; unmatched subtitles are reported in the status bar.
2026-07-08 10:37:56 +02:00
parent 304d9ad047
commit c7c125d40b
9 changed files with 511 additions and 21 deletions
@@ -0,0 +1,61 @@
+using System.IO;
+using System.Text.RegularExpressions;
+
+namespace Futonizer.Services;
+
+/// <summary>
+/// Recognises subtitle files by extension and extracts a normalized episode
+/// code (e.g. "S04E06") from a filename, used to match dropped subtitle
+/// files to the video file with the same episode code.
+/// </summary>
+public static class SubtitleMatcher
+{
+    /// <summary>
+    /// Every subtitle container/format extension mkvmerge (and therefore
+    /// Futonizer) can mux in: SubRip, (Advanced) SubStation Alpha, VobSub,
+    /// WebVTT, HDMV/PGS, Universal Subtitle Format, SAMI, TTML/DFXP, EBU-STL,
+    /// MicroDVD/SubViewer (both commonly saved with a plain ".sub" extension),
+    /// and Kate.
+    /// </summary>
+    public static readonly string[] SupportedExtensions =
+    {
+        ".srt", ".ass", ".ssa", ".sub", ".idx", ".vtt", ".webvtt",
+        ".sup", ".pgs", ".usf", ".smi", ".sami", ".ttml", ".dfxp",
+        ".stl", ".kate",
+    };
+
+    public static bool IsSubtitleFile(string path)
+    {
+        string ext = Path.GetExtension(path);
+        return !string.IsNullOrEmpty(ext)
+               && SupportedExtensions.Contains(ext, StringComparer.OrdinalIgnoreCase);
+    }
+
+    // "S04E06", "S4E6", "S04 E06", "S04-E06", "S04.E06" — the standard scene/anime tagging scheme.
+    private static readonly Regex SeasonEpisodeRegex =
+        new(@"S(\d{1,4})[\s._-]*E(\d{1,4})", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    // Fallback: "4x06" style season x episode separator.
+    private static readonly Regex SeasonXEpisodeRegex =
+        new(@"(?<![\d.])(\d{1,2})x(\d{2,3})(?!\d)", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    /// <summary>
+    /// Extracts and normalizes the episode code from a filename (e.g.
+    /// "Show.S4E6.1080p.mkv" and "Show - 04x06 - Title.srt" both return
+    /// "S04E06"), so files can be matched regardless of zero-padding or
+    /// separator style. Returns null if no episode code is found.
+    /// </summary>
+    public static string? ExtractEpisodeCode(string fileName)
+    {
+        var match = SeasonEpisodeRegex.Match(fileName);
+        if (!match.Success)
+            match = SeasonXEpisodeRegex.Match(fileName);
+
+        if (!match.Success) return null;
+
+        if (!int.TryParse(match.Groups[1].Value, out int season)) return null;
+        if (!int.TryParse(match.Groups[2].Value, out int episode)) return null;
+
+        return $"S{season:D2}E{episode:D2}";
+    }
+}