Move cancellation check outside of the ThrowIfExitCodeNotZero() and call it separately in all the async code paths.

This preserves the original semantics and contract (throw only if the ffprobe exits with a non-zero code).

FFMpegCore.Test/VideoTest.cs

@@ -82,6 +82,40 @@ public class VideoTest
         Assert.IsTrue(success);
     }
 
+    [TestMethod]
+    [Timeout(BaseTimeoutMilliseconds, CooperativeCancellation = true)]
+    public async Task Video_MetadataBuilder()
+    {
+        using var outputFile = new TemporaryFile($"out{VideoType.Mp4.Extension}");
+
+        await FFMpegArguments
+            .FromFileInput(TestResources.WebmVideo)
+            .AddMetaData(FFMetadataBuilder.Empty()
+                .WithTag("title", "noname")
+                .WithTag("artist", "unknown")
+                .WithChapter("Chapter 1", 1.1)
+                .WithChapter("Chapter 2", 1.23))
+            .OutputToFile(outputFile, false, opt => opt
+                .WithVideoCodec(VideoCodec.LibX264))
+            .CancellableThrough(TestContext.CancellationToken)
+            .ProcessAsynchronously();
+
+        var analysis = await FFProbe.AnalyseAsync(outputFile, cancellationToken: TestContext.CancellationToken);
+        Assert.IsTrue(analysis.Format.Tags!.TryGetValue("title", out var title));
+        Assert.IsTrue(analysis.Format.Tags!.TryGetValue("artist", out var artist));
+        Assert.AreEqual("noname", title);
+        Assert.AreEqual("unknown", artist);
+
+        Assert.HasCount(2, analysis.Chapters);
+        Assert.AreEqual("Chapter 1", analysis.Chapters.First().Title);
+        Assert.AreEqual(1.1, analysis.Chapters.First().Duration.TotalSeconds);
+        Assert.AreEqual(1.1, analysis.Chapters.First().End.TotalSeconds);
+
+        Assert.AreEqual("Chapter 2", analysis.Chapters.Last().Title);
+        Assert.AreEqual(1.23, analysis.Chapters.Last().Duration.TotalSeconds);
+        Assert.AreEqual(1.1 + 1.23, analysis.Chapters.Last().End.TotalSeconds);
+    }
+
     [TestMethod]
     [Timeout(BaseTimeoutMilliseconds, CooperativeCancellation = true)]
     public void Video_ToH265_MKV_Args()

FFMpegCore/FFMetadataInputArgument.cs

@@ -0,0 +1,62 @@
+using System.Text;
+
+namespace FFMpegCore;
+
+public class FFMetadataBuilder
+{
+    private Dictionary<string, string> Tags { get; } = new();
+    private List<FFMetadataChapter> Chapters { get; } = [];
+
+    public static FFMetadataBuilder Empty()
+    {
+        return new FFMetadataBuilder();
+    }
+
+    public FFMetadataBuilder WithTag(string key, string value)
+    {
+        Tags.Add(key, value);
+        return this;
+    }
+
+    public FFMetadataBuilder WithChapter(string title, long durationMs)
+    {
+        Chapters.Add(new FFMetadataChapter(title, durationMs));
+        return this;
+    }
+
+    public FFMetadataBuilder WithChapter(string title, double durationSeconds)
+    {
+        Chapters.Add(new FFMetadataChapter(title, Convert.ToInt64(durationSeconds * 1000)));
+        return this;
+    }
+
+    public string GetMetadataFileContent()
+    {
+        var sb = new StringBuilder();
+        sb.AppendLine(";FFMETADATA1");
+
+        foreach (var tag in Tags)
+        {
+            sb.AppendLine($"{tag.Key}={tag.Value}");
+        }
+
+        long totalDurationMs = 0;
+        foreach (var chapter in Chapters)
+        {
+            sb.AppendLine("[CHAPTER]");
+            sb.AppendLine("TIMEBASE=1/1000");
+            sb.AppendLine($"START={totalDurationMs}");
+            sb.AppendLine($"END={totalDurationMs + chapter.DurationMs}");
+            sb.AppendLine($"title={chapter.Title}");
+            totalDurationMs += chapter.DurationMs;
+        }
+
+        return sb.ToString();
+    }
+
+    private class FFMetadataChapter(string title, long durationMs)
+    {
+        public string Title { get; } = title;
+        public long DurationMs { get; } = durationMs;
+    }
+}

FFMpegCore/FFMpeg/FFMpegArguments.cs

@@ -109,6 +109,11 @@ public sealed class FFMpegArguments : FFMpegArgumentsBase
         return WithInput(new MetaDataArgument(content), addArguments);
     }
 
+    public FFMpegArguments AddMetaData(FFMetadataBuilder metaDataBuilder, Action<FFMpegArgumentOptions>? addArguments = null)
+    {
+        return WithInput(new MetaDataArgument(metaDataBuilder.GetMetadataFileContent()), addArguments);
+    }
+
     public FFMpegArguments AddMetaData(IReadOnlyMetaData metaData, Action<FFMpegArgumentOptions>? addArguments = null)
     {
         return WithInput(new MetaDataArgument(MetaDataSerializer.Instance.Serialize(metaData)), addArguments);

FFMpegCore/FFProbe/FFProbe.cs

@@ -84,7 +84,8 @@ public static class FFProbe
 
         var instance = PrepareStreamAnalysisInstance(filePath, ffOptions ?? GlobalFFOptions.Current, customArguments);
         var result = await instance.StartAndWaitForExitAsync(cancellationToken).ConfigureAwait(false);
-        ThrowIfExitCodeNotZero(result, cancellationToken);
+        cancellationToken.ThrowIfCancellationRequested();
+        ThrowIfExitCodeNotZero(result);
 
         return ParseOutput(result);
     }
@@ -123,7 +124,8 @@ public static class FFProbe
     {
         var instance = PrepareStreamAnalysisInstance(uri.AbsoluteUri, ffOptions ?? GlobalFFOptions.Current, customArguments);
         var result = await instance.StartAndWaitForExitAsync(cancellationToken).ConfigureAwait(false);
-        ThrowIfExitCodeNotZero(result, cancellationToken);
+        cancellationToken.ThrowIfCancellationRequested();
+        ThrowIfExitCodeNotZero(result);
 
         return ParseOutput(result);
     }
@@ -150,7 +152,8 @@ public static class FFProbe
         }
 
         var result = await task.ConfigureAwait(false);
-        ThrowIfExitCodeNotZero(result, cancellationToken);
+        cancellationToken.ThrowIfCancellationRequested();
+        ThrowIfExitCodeNotZero(result);
 
         pipeArgument.Post();
         return ParseOutput(result);
@@ -212,13 +215,10 @@ public static class FFProbe
         }
     }
 
-    private static void ThrowIfExitCodeNotZero(IProcessResult result, CancellationToken cancellationToken = default)
+    private static void ThrowIfExitCodeNotZero(IProcessResult result)
     {
         if (result.ExitCode != 0)
         {
-            // if cancellation requested, then we are not interested in the exit code, just throw the cancellation exception
-            // to get consistent and expected behavior.
-            cancellationToken.ThrowIfCancellationRequested();
             var message = $"ffprobe exited with non-zero exit-code ({result.ExitCode} - {string.Join("\n", result.ErrorData)})";
             throw new FFMpegException(FFMpegExceptionType.Process, message, null, string.Join("\n", result.ErrorData));
         }