Add method to locate subtitle files for video

A method 'TryLocateSubtitleFile' was implemented in FileUtil. It attempts to locate matching subtitle files for video files in known directories. The method was integrated into 'AddInputFile' of 'GenerateVideoWithHardSubs' and simplifies the earlier implementation for finding subtitles. This change will make the process of matching video files to subtitles more efficient and cleaner.

Signed-off-by: Ivandro Jao <ivandrofly@gmail.com>

src/libse/Common/FileUtil.cs

@@ -6,6 +6,7 @@ using Nikse.SubtitleEdit.Core.VobSub;
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Text;
 using System.Text.RegularExpressions;
 
@@ -707,5 +708,57 @@ namespace Nikse.SubtitleEdit.Core.Common
 
             return false;
         }
+
+        public static string TryLocateSubtitleFile(string path, string videoFileNameNoExtension)
+        {
+            // search in these directories
+            var knownSubtitleDirectories = new[]
+            {
+                path, Path.Combine(path, "Subs"), Path.Combine(path, "Sub"), Path.Combine(path, "Subtitles")
+            };
+            foreach (var knownSubtitleDirectory in knownSubtitleDirectories)
+            {
+                var subtitleFileFromKnownDirectory = LocateSubtitle(knownSubtitleDirectory, videoFileNameNoExtension);
+                if (!string.IsNullOrEmpty(subtitleFileFromKnownDirectory))
+                {
+                    return subtitleFileFromKnownDirectory;
+                }
+            }
+
+            return string.Empty;
+
+            string LocateSubtitle(string localPath, in string localVideoFileName)
+            {
+                if (!Directory.Exists(localPath))
+                {
+                    return string.Empty;
+                }
+
+                // try to locate subtitle file that has the same name as the video file
+                var defaultSubtitles = new[]
+                {
+                    Path.Combine(localPath, Path.ChangeExtension(localVideoFileName, ".ass")),
+                    Path.Combine(localPath, Path.ChangeExtension(localVideoFileName, ".srt"))
+                };
+                foreach (var defaultSubtitle in defaultSubtitles)
+                {
+                    if (File.Exists(defaultSubtitle))
+                    {
+                        return defaultSubtitle;
+                    }
+                }
+
+                var assEnumerable = Directory.EnumerateFiles(localPath, "*.ass", SearchOption.TopDirectoryOnly);
+                var subripEnumerable = Directory.EnumerateFiles(localPath, "*.srt", SearchOption.TopDirectoryOnly);
+                var subtitleFile = assEnumerable.Concat(subripEnumerable).FirstOrDefault();
+                // subtitle file found in top directory
+                if (!string.IsNullOrEmpty(subtitleFile))
+                {
+                    return subtitleFile;
+                }
+
+                return string.Empty;
+            }
+        }
     }
 }

src/ui/Forms/GenerateVideoWithHardSubs.cs

@@ -2131,54 +2131,32 @@ namespace Nikse.SubtitleEdit.Forms
             }
         }
 
-        private void AddInputFile(string fileName)
+        private void AddInputFile(string videoFileName)
         {
-            if (string.IsNullOrEmpty(fileName))
+            if (string.IsNullOrEmpty(videoFileName))
             {
                 return;
             }
 
-            var ext = Path.GetExtension(fileName).ToLowerInvariant();
+            var ext = Path.GetExtension(videoFileName).ToLowerInvariant();
-            if ((Utilities.AudioFileExtensions.Contains(ext) || Utilities.VideoFileExtensions.Contains(ext)) && File.Exists(fileName))
+            if ((Utilities.AudioFileExtensions.Contains(ext) || Utilities.VideoFileExtensions.Contains(ext)) && File.Exists(videoFileName))
             {
                 var item = new BatchVideoAndSub();
-                item.VideoFileName = fileName;
+                item.VideoFileName = videoFileName;
-                item.VideoFileSizeInBytes = new FileInfo(fileName).Length;
+                item.VideoFileSizeInBytes = new FileInfo(videoFileName).Length;
 
-                var path = Path.GetDirectoryName(fileName);
+                var path = Path.GetDirectoryName(videoFileName);
-                var fileNameNoExt = Path.GetFileNameWithoutExtension(fileName);
+                var fileNameNoExt = Path.GetFileNameWithoutExtension(videoFileName);
-                var subFileName = Path.ChangeExtension(fileName, ".ass");
 
-                if (!File.Exists(subFileName))
+                // try locate subtitle file for the input vide file
+                var subtitleFile = FileUtil.TryLocateSubtitleFile(path, videoFileName);
+                if (File.Exists(subtitleFile))
                 {
-                    subFileName = Path.ChangeExtension(fileName, ".srt");
+                    item.SubtitleFileName = subtitleFile;
+                    item.SubtitleFileFileSizeInBytes = new FileInfo(subtitleFile).Length;
                 }
 
-                if (!File.Exists(subFileName))
+                var mediaInfo = FfmpegMediaInfo.Parse(videoFileName);
-                {
-                    var files = Directory.GetFiles(path, fileNameNoExt + "*.ass");
-                    if (files.Length > 0)
-                    {
-                        subFileName = files[0];
-                    }
-                }
-
-                if (!File.Exists(subFileName))
-                {
-                    var files = Directory.GetFiles(path, fileNameNoExt + "*.srt");
-                    if (files.Length > 0)
-                    {
-                        subFileName = files[0];
-                    }
-                }
-
-                if (File.Exists(subFileName))
-                {
-                    item.SubtitleFileName = subFileName;
-                    item.SubtitleFileFileSizeInBytes = new FileInfo(subFileName).Length;
-                }
-
-                var mediaInfo = FfmpegMediaInfo.Parse(fileName);
                 int width;
                 int height;
                 if (mediaInfo.VideoWidth > 0 && mediaInfo.VideoHeight > 0)
@@ -2189,18 +2167,18 @@ namespace Nikse.SubtitleEdit.Forms
                 else
                 {
                     var vInfo = new VideoInfo { Success = false };
-                    if (fileName.EndsWith(".mp4", StringComparison.OrdinalIgnoreCase))
+                    if (videoFileName.EndsWith(".mp4", StringComparison.OrdinalIgnoreCase))
                     {
-                        vInfo = QuartsPlayer.GetVideoInfo(fileName);
+                        vInfo = QuartsPlayer.GetVideoInfo(videoFileName);
                         if (!vInfo.Success)
                         {
-                            vInfo = LibMpvDynamic.GetVideoInfo(fileName);
+                            vInfo = LibMpvDynamic.GetVideoInfo(videoFileName);
                         }
                     }
 
                     if (!vInfo.Success)
                     {
-                        vInfo = UiUtil.GetVideoInfo(fileName);
+                        vInfo = UiUtil.GetVideoInfo(videoFileName);
                     }
 
                     width = vInfo.Width;
@@ -2209,11 +2187,11 @@ namespace Nikse.SubtitleEdit.Forms
 
                 if (width == 0 || height == 0)
                 {
-                    SeLogger.Error("Skipping burn-in file with no video: " + fileName);
+                    SeLogger.Error("Skipping burn-in file with no video: " + videoFileName);
                     return; // skip audio or damaged files
                 }
 
-                var listViewItem = new ListViewItem(fileName);
+                var listViewItem = new ListViewItem(videoFileName);
                 listViewItem.Tag = item;
                 listViewItem.SubItems.Add($"{width}x{height}");
                 var s = Utilities.FormatBytesToDisplayFileSize(item.VideoFileSizeInBytes);