fix drop frame rate

Form1.Designer.cs

@@ -109,7 +109,7 @@
             this.dataGridView1.Name = "dataGridView1";
             this.dataGridView1.ReadOnly = true;
             this.dataGridView1.RowTemplate.Height = 24;
-            this.dataGridView1.Size = new System.Drawing.Size(587, 141);
+            this.dataGridView1.Size = new System.Drawing.Size(586, 141);
             this.dataGridView1.TabIndex = 8;
             // 
             // FilePath
@@ -117,6 +117,7 @@
             this.FilePath.HeaderText = "File Path";
             this.FilePath.Name = "FilePath";
             this.FilePath.ReadOnly = true;
+            this.FilePath.Width = 272;
             // 
             // Status
             // 

Form1.cs

@@ -116,11 +116,24 @@ namespace CompressH265 {
                 return;
             }
         
+            // Get FPS
+            var fps = GetFPS(inputFilename);
+            var fpsParam = "";
+
+            if (fps > 0) {
+                fpsParam = "-r " + fps;
+            }
+
+
+            
+            // Converting
             process.StartInfo.FileName = "ffmpeg.exe";
-            process.StartInfo.Arguments = $"-i \"{inputFilename}\" -vcodec hevc -map_metadata 0 -vf yadif -crf 16 -preset medium \"{outputFilename}\"";
+            process.StartInfo.Arguments = $" -i \"{inputFilename}\" -vcodec hevc -map_metadata 0 -vf yadif -crf 20 -preset medium {fpsParam} \"{outputFilename}\"";
             process.StartInfo.UseShellExecute = false;
             process.StartInfo.CreateNoWindow = true;
 
+            MessageBox.Show(process.StartInfo.Arguments);
+            
             var rowID = nextTaskID++;
             var msgQueue = new Queue<string>();
             dataGridView1.Rows.Insert(rowID, shortName, "Preparing...");
@@ -166,6 +179,39 @@ namespace CompressH265 {
             processList.AddLast(process);
         }
 
+        private float GetFPS(string inputFilename) {
+            Process process = new Process();
+            process.StartInfo.FileName = "ffmpeg.exe";
+            process.StartInfo.Arguments = $"-i \"{inputFilename}\"";
+            process.StartInfo.UseShellExecute = false;
+            process.StartInfo.CreateNoWindow = true;
+            process.StartInfo.RedirectStandardError = true;
+            process.Start();
+            process.WaitForExit();
+            string err = process.StandardError.ReadToEnd();
+            
+            var end = err.IndexOf(" fps,");
+
+            if (end < 0) {
+                return -1f;
+            }
+
+            var start = end;
+
+            while (true) {
+                if (err[start - 1] == ' ') {
+                    break;
+                }
+                start--;
+
+                if (start < 0) {
+                    return -1;
+                }
+            }
+
+            return float.Parse(err.Substring(start, end - start));
+        }
+
         private void button3_Click(object sender, EventArgs e) {
             ProcessStartInfo info = new ProcessStartInfo();
             info.FileName = System.Reflection.Assembly.GetExecutingAssembly().Location;