Arguments: DurationArgument

#33 

* added format provider to correctly parse the video's duration

* added DurationArgument

FFMpegCore.Test/ArgumentBuilderTest.cs

@@ -214,5 +214,12 @@ public void Builder_BuildString_Codec_Override()
 
             Assert.AreEqual(str, "-i \"input.mp4\" -codec:v libx264 -pix_fmt yuv420p -y \"output.mp4\"");
         }
+
+        [TestMethod]
+        public void Builder_BuildString_Duration() {
+            var str = GetArgumentsString(new DurationArgument(TimeSpan.FromSeconds(20)));
+
+            Assert.AreEqual(str, "-i \"input.mp4\" -t 00:00:20 \"output.mp4\"");
+        }
     }
 }

FFMpegCore.Test/VideoTest.cs

@@ -3,6 +3,7 @@
 using FFMpegCore.FFMPEG.Enums;
 using FFMpegCore.Test.Resources;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System;
 using System.Collections.Generic;
 using System.Drawing.Imaging;
 using System.IO;
@@ -318,5 +319,27 @@ public void Video_With_Only_Audio_Should_Extract_Metadata()
             Assert.AreEqual(video.Duration.TotalSeconds, 79);
             Assert.AreEqual(video.Size, 1.25);
         }
+
+        [TestMethod]
+        public void Video_Duration() {
+            var video = VideoInfo.FromFileInfo(VideoLibrary.LocalVideo);
+            var output = Input.OutputLocation(VideoType.Mp4);
+
+            var arguments = new ArgumentContainer();
+            arguments.Add(new InputArgument(VideoLibrary.LocalVideo));
+            arguments.Add(new DurationArgument(TimeSpan.FromSeconds(video.Duration.TotalSeconds - 5)));
+            arguments.Add(new OutputArgument(output));
+
+            try {
+                Encoder.Convert(arguments);
+
+                Assert.IsTrue(File.Exists(output.FullName));
+                var outputVideo = new VideoInfo(output.FullName);
+                Assert.AreEqual(video.Duration.TotalSeconds - 5, outputVideo.Duration.TotalSeconds);
+            } finally {
+                if (File.Exists(output.FullName))
+                    output.Delete();
+            }
+        }
     }
 }

FFMpegCore/FFMPEG/Argument/ArgumentStringifier.cs

@@ -201,5 +201,10 @@ internal static string StartNumber(int v)
         {
             return $"-start_number {v} ";
         }
+
+        internal static string Duration(TimeSpan? duration)
+        {
+            return !duration.HasValue ? string.Empty : $"-t {duration} ";
+        }
     }
 }

FFMpegCore/FFMPEG/Argument/Atoms/DurationArgument.cs

@@ -0,0 +1,27 @@
+using System;
+
+namespace FFMpegCore.FFMPEG.Argument
+{
+    /// <summary>
+    /// Represents duration parameter
+    /// </summary>
+    public class DurationArgument : Argument<TimeSpan?>
+    {
+        public DurationArgument()
+        {
+        }
+
+        public DurationArgument(TimeSpan? value) : base(value)
+        {
+        }
+
+        /// <summary>
+        /// String representation of the argument
+        /// </summary>
+        /// <returns>String representation of the argument</returns>
+        public override string GetStringValue()
+        {
+            return ArgumentStringifier.Duration(Value);
+        }
+    }
+}