Implement FfProbeKeyframeExtractor and add tests for it

tests/Jellyfin.MediaEncoding.Keyframes.Tests/FfProbe/FfProbeKeyframeExtractorTests.cs

@@ -0,0 +1,28 @@
+using System.IO;
+using System.Text.Json;
+using Xunit;
+
+namespace Jellyfin.MediaEncoding.Keyframes.FfProbe
+{
+    public class FfProbeKeyframeExtractorTests
+    {
+        [Theory]
+        [InlineData("keyframes.txt", "keyframes_result.json")]
+        [InlineData("keyframes_streamduration.txt", "keyframes_streamduration_result.json")]
+        public void ParseStream_Valid_Success(string testDataFileName, string resultFileName)
+        {
+            var testDataPath = Path.Combine("FfProbe/Test Data", testDataFileName);
+            var resultPath = Path.Combine("FfProbe/Test Data", resultFileName);
+            var resultFileStream = File.OpenRead(resultPath);
+            var expectedResult = JsonSerializer.Deserialize<KeyframeData>(resultFileStream)!;
+
+            using var fileStream = File.OpenRead(testDataPath);
+            using var streamReader = new StreamReader(fileStream);
+
+            var result = FfProbeKeyframeExtractor.ParseStream(streamReader);
+
+            Assert.Equal(expectedResult.TotalDuration, result.TotalDuration);
+            Assert.Equal(expectedResult.KeyframeTicks, result.KeyframeTicks);
+        }
+    }
+}