Add first draft of keyframe extraction for Matroska

src/Jellyfin.MediaEncoding.Keyframes/KeyframeExtractor.cs

@@ -0,0 +1,56 @@
+using System;
+using System.IO;
+using Jellyfin.MediaEncoding.Keyframes.FfProbe;
+using Jellyfin.MediaEncoding.Keyframes.FfTool;
+using Jellyfin.MediaEncoding.Keyframes.Matroska;
+using Microsoft.Extensions.Logging;
+
+namespace Jellyfin.MediaEncoding.Keyframes
+{
+    /// <summary>
+    /// Manager class for the set of keyframe extractors.
+    /// </summary>
+    public class KeyframeExtractor
+    {
+        private readonly ILogger<KeyframeExtractor> _logger;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="KeyframeExtractor"/> class.
+        /// </summary>
+        /// <param name="logger">An instance of the <see cref="ILogger{KeyframeExtractor}"/> interface.</param>
+        public KeyframeExtractor(ILogger<KeyframeExtractor> logger)
+        {
+            _logger = logger;
+        }
+
+        /// <summary>
+        /// Extracts the keyframe positions from a video file.
+        /// </summary>
+        /// <param name="filePath">Absolute file path to the media file.</param>
+        /// <param name="ffProbePath">Absolute file path to the ffprobe executable.</param>
+        /// <param name="ffToolPath">Absolute file path to the fftool executable.</param>
+        /// <returns></returns>
+        public KeyframeData GetKeyframeData(string filePath, string ffProbePath, string ffToolPath)
+        {
+            var extension = Path.GetExtension(filePath);
+            if (string.Equals(extension, ".mkv", StringComparison.OrdinalIgnoreCase))
+            {
+                try
+                {
+                    return MatroskaKeyframeExtractor.GetKeyframeData(filePath);
+                }
+                catch (InvalidOperationException ex)
+                {
+                    _logger.LogError(ex, "{MatroskaKeyframeExtractor} failed to extract keyframes", nameof(MatroskaKeyframeExtractor));
+                }
+            }
+
+            if (!string.IsNullOrEmpty(ffToolPath))
+            {
+                return FfToolKeyframeExtractor.GetKeyframeData(ffToolPath, filePath);
+            }
+
+            return FfProbeKeyframeExtractor.GetKeyframeData(ffProbePath, filePath);
+        }
+    }
+}