Added a loop for Ultra quality

The loop implemented attempts to lower the bitrate until the targeted size
is met. It will run 10 times or until the target size is met. If it goes past 10
passes, it will give the user an error message with recommendations.

Author: MasterOfWebM

Helper.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Text;
@@ -45,5 +46,24 @@ public static double getFileSize(String file)
 
             return Math.Round(fileSize / 1024, 2);
         }
+
+        /// <summary>
+        /// Calls ffmpeg to encode the video
+        /// </summary>
+        /// <param name="command">The base command string (passes are entered automatically by this class)</param>
+        /// <param name="fileOutput">The path to the output</param>
+        public static void encodeVideo(String command, String fileOutput)
+        {
+            String commandPass1 = "-pass 1 -f webm NUL";
+            String commandPass2 = "-pass 2 ";
+
+            // Pass 1
+            var pass1 = Process.Start("ffmpeg", command + commandPass1);
+            pass1.WaitForExit();
+
+            // Pass 2
+            var pass2 = Process.Start("ffmpeg", command + commandPass2 + "\"" + fileOutput + "\"");
+            pass2.WaitForExit();
+        }
     }
 }

formMain.cs

@@ -61,14 +61,14 @@ private void btnConvert_Click(object sender, EventArgs e)
 
             // Base command where each element gets replaced
             String baseCommand = "-y {time1} -i \"{input}\" {time2} -t {length} -c:v libvpx -b:v {bitrate} {scale} -threads {threads} {quality} -an ";
-            String commandPass1 = "-pass 1 -f webm NUL";
-            String commandPass2 = "-pass 2 ";
             String filterCommands = null;
 
             // Verification boolean just incase the user messes up
             bool verified = true;
             bool filters = false;
 
+            double bitrate = 0;
+
             // Validates if the user input a value for txtInput
             if (txtInput.Text == "")
             {
@@ -160,7 +160,7 @@ private void btnConvert_Click(object sender, EventArgs e)
             }
             else
             {
-                double bitrate = Helper.calcBitrate(txtMaxSize.Text, txtLength.Text);
+                bitrate = Helper.calcBitrate(txtMaxSize.Text, txtLength.Text);
 
                 // Changes the quality to what the user selected
                 switch (comboQuality.Text)
@@ -174,7 +174,6 @@ private void btnConvert_Click(object sender, EventArgs e)
                         baseCommand = baseCommand.Replace("{bitrate}", bitrate.ToString() + "K");
                         break;
                     case "Ultra":
-                        // TODO: Add a method to get the output as close to user specified filesize as possible
                         baseCommand = baseCommand.Replace("{quality}", "-quality best -auto-alt-ref 1 -lag-in-frames 16 -slices 8");
                         bitrate = Convert.ToDouble(bitrate) * 1024;
                         baseCommand = baseCommand.Replace("{bitrate}", bitrate.ToString());
@@ -200,13 +199,7 @@ private void btnConvert_Click(object sender, EventArgs e)
 
                 try
                 {
-                    // Pass 1
-                    var pass1 = Process.Start("ffmpeg", baseCommand + commandPass1);
-                    pass1.WaitForExit();
-
-                    // Pass 2
-                    var pass2 = Process.Start("ffmpeg", baseCommand + commandPass2 + "\"" + txtOutput.Text + "\"");
-                    pass2.WaitForExit();
+                    Helper.encodeVideo(baseCommand, txtOutput.Text);
                 }
                 catch (Win32Exception ex)
                 {
@@ -215,16 +208,55 @@ private void btnConvert_Click(object sender, EventArgs e)
                     Debug.WriteLine(ex);
                 }
 
-                if (Helper.getFileSize(txtOutput.Text) < Convert.ToDouble(txtMaxSize.Text) * 1024)
+                double fileSize = Helper.getFileSize(txtOutput.Text);
+
+                if (fileSize < Convert.ToDouble(txtMaxSize.Text) * 1024)
                 {
                     // Clears the output box so user's don't overwrite their previous output
-                    txtOutput.Text = null;
+                    txtOutput.Text = "";
                 }
                 else
                 {
-                    MessageBox.Show("The final clip is larger than " + txtMaxSize.Text + "MB.\n" +
-                        "This occured because the clip's resolution was too large,\n" + 
-                        "and/or because the clip was too long for the inputted size.");
+                    if (comboQuality.Text == "Ultra")
+                    {
+                        /*
+                         * Automatically attempt to create a smaller file
+                         * If it doesn't work within 10 attempts, recommend
+                         * 'Best' quality
+                         */
+                        int passes = 0;
+
+                        while (fileSize > Convert.ToDouble(txtMaxSize.Text) * 1024 && passes <= 10)
+                        {
+                            // Lowers the bitrate by 1k
+                            bitrate -= 1000;
+
+                            // Replacing the whole command just in case the file name contains the same numbers
+                            baseCommand = baseCommand.Replace("-b:v " + (bitrate + 1000), "-b:v " + bitrate);
+
+                            Helper.encodeVideo(baseCommand, txtOutput.Text);
+                            passes++;
+
+                            // Gets the filesize after encoding
+                            fileSize = Helper.getFileSize(txtOutput.Text);
+                        }
+
+                        if (fileSize < Convert.ToDouble(txtMaxSize.Text) * 1024)
+                        {
+                            txtOutput.Text = "";
+                        }
+                        else
+                            MessageBox.Show("Could not get the file size below " + txtMaxSize.Text + "MB.\n" +
+                                "Try using 'Best' quality, and if that doesn't work,\n" +
+                                "you must reduce your resolution and/or shorten the length.",
+                                "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                    }
+                    else
+                    {
+                        MessageBox.Show("The final clip is larger than " + txtMaxSize.Text + "MB.\n" +
+                            "This occured because the clip's resolution was too large,\n" +
+                            "and/or because the clip was too long for the inputted size.");
+                    }
                 }
             }