Keep video in sync with audio

OpenRA.Game/Widgets/VqaPlayerWidget.cs

@@ -12,6 +12,7 @@ using System;
 using System.Drawing;
 using OpenRA.FileFormats;
 using OpenRA.Graphics;
+using OpenRA.Support;
 
 namespace OpenRA.Widgets
 {
@@ -23,41 +24,42 @@ namespace OpenRA.Widgets
 		Sprite videoSprite;
 		VqaReader video = null;
 		
+		float invLength;
 		public void LoadVideo(string filename)
 		{
 			video = new VqaReader(FileSystem.Open(filename));
-			timestep = 1e3f/video.Framerate;
-			
+			timestep = 1f/video.Framerate;
+			invLength = video.Framerate*1f/video.Frames;
+
 			var size = OpenRA.Graphics.Util.NextPowerOf2(Math.Max(video.Width, video.Height));
 			videoSprite = new Sprite(new Sheet(new Size(size,size)), new Rectangle( 0, 0, video.Width, video.Height ), TextureChannel.Alpha);
 		}
 
-		int lastTime;
+		bool first = true;
 		bool advanceNext = false;
+		Stopwatch sw = new Stopwatch();
 		public override void DrawInner(World world)
 		{
 			if (video == null)
-			{
-				LoadVideo(Video);
-				Sound.PlayRaw(video.AudioData);
-			}
-			
-			int t = Environment.TickCount;
-			int dt = t - lastTime;
-			
-			if (advanceNext)
-			{
-				if (video.CurrentFrame == 0)
-					Sound.PlayRaw(video.AudioData);
-				advanceNext = false;
-				video.AdvanceFrame();
-			}
-			
-			if (dt > timestep)
+				LoadVideo(Video);
+						
+			var nextFrame = (int)float2.Lerp(0, video.Frames, (float)(sw.ElapsedTime()*invLength));
+			if (first || nextFrame > video.Frames)
 			{
-				lastTime = t;
-				advanceNext = true;
+				video.Reset();
+				sw.Reset();
+				Sound.PlayRaw(video.AudioData);
+				
+				nextFrame = 0;
 				videoSprite.sheet.Texture.SetData(video.FrameData());
+				first = false;
+			}
+			
+			while (nextFrame > video.CurrentFrame)
+			{
+				video.AdvanceFrame();
+				if (nextFrame == video.CurrentFrame)
+					videoSprite.sheet.Texture.SetData(video.FrameData());
 			}
 			
 			Game.Renderer.RgbaSpriteRenderer.DrawSprite(videoSprite, new int2(RenderBounds.X,RenderBounds.Y), "chrome");