Add OutputToNull method to handle the null muxer argument

FFMpegCore.Test/ArgumentBuilderTest.cs

@@ -766,6 +766,13 @@ public void OutputPipe_MaxLength_ShorterThanMacOSMax()
         Assert.IsLessThan(_macOsMaxPipePathLength, pipePath.Length);
     }
 
+    [TestMethod]
+    public void Builder_BuildString_Null_Output()
+    {
+        var str = FFMpegArguments.FromFileInput("input.mp4").OutputToNull(opt => opt.WithCustomArgument("-filter_complex ebur128")).Arguments;
+        Assert.AreEqual("-i \"input.mp4\" -filter_complex ebur128 -f null -", str);
+    }
+
     [TestMethod]
     public void Builder_BuildString_LowPassFilterDefault()
     {

FFMpegCore/FFMpeg/Arguments/OutputNullArgument.cs

@@ -0,0 +1,16 @@
+namespace FFMpegCore.Arguments;
+
+public class OutputNullArgument : IOutputArgument
+{
+    public string Text => "-f null -";
+
+    public Task During(CancellationToken cancellationToken = default) => Task.CompletedTask;
+
+    public void Post()
+    {
+    }
+
+    public void Pre()
+    {
+    }
+}

FFMpegCore/FFMpeg/FFMpegArguments.cs

@@ -156,7 +156,7 @@ public FFMpegArgumentProcessor OutputToPipe(IPipeSink reader, Action<FFMpegArgum
     {
         return ToProcessor(new OutputPipeArgument(reader), addArguments);
     }
-
+    
     private FFMpegArgumentProcessor ToProcessor(IOutputArgument argument, Action<FFMpegArgumentOptions>? addArguments)
     {
         var args = new FFMpegArgumentOptions();
@@ -180,6 +180,11 @@ public FFMpegArgumentProcessor MultiOutput(Action<FFMpegMultiOutputOptions> addO
         Arguments.AddRange(args.Arguments);
         return new FFMpegArgumentProcessor(this);
     }
+
+    public FFMpegArgumentProcessor OutputToNull(Action<FFMpegArgumentOptions>? addArguments = null)
+    {
+        return ToProcessor(new OutputNullArgument(), addArguments);
+    }
 
     internal void Pre()
     {