Keep video in sync with audio

OpenRA.FileFormats/Graphics/VqaReader.cs

@@ -109,9 +109,13 @@ namespace OpenRA.FileFormats
 
 			CollectAudioData();
 			
-			// Load the first frame
-			currentFrame = 0;
-			AdvanceFrame();
+			Reset();
+		}
+
+		public void Reset()
+		{
+			currentFrame = cbOffset = cbChunk = 0;
+			LoadFrame();
 		}
 		
 		void CollectAudioData()
@@ -150,6 +154,15 @@ namespace OpenRA.FileFormats
 
 		public void AdvanceFrame()
 		{
+			currentFrame++;
+			LoadFrame();
+		}
+		
+		void LoadFrame()
+		{			
+			if (currentFrame >= Frames)
+				return;
+			
 			// Seek to the start of the frame
 			stream.Seek(offsets[currentFrame], SeekOrigin.Begin);
 			BinaryReader reader = new BinaryReader(stream);
@@ -176,8 +189,6 @@ namespace OpenRA.FileFormats
 				// Chunks are aligned on even bytes; advance by a byte if the next one is null
 				if (reader.PeekChar() == 0) reader.ReadByte();
 			}
-			if (++currentFrame == Frames)
-				currentFrame = cbOffset = cbChunk = 0;
 		}
 		
 		// VQA Frame

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
 {
@@ -23,40 +24,41 @@ 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);
+						
+			var nextFrame = (int)float2.Lerp(0, video.Frames, (float)(sw.ElapsedTime()*invLength));
+			if (first || nextFrame > video.Frames)
+			{
+				video.Reset();
+				sw.Reset();
 				Sound.PlayRaw(video.AudioData);
+				
+				nextFrame = 0;
+				videoSprite.sheet.Texture.SetData(video.FrameData());
+				first = false;
 			}
 			
-			int t = Environment.TickCount;
-			int dt = t - lastTime;
-			
-			if (advanceNext)
+			while (nextFrame > video.CurrentFrame)
 			{
-				if (video.CurrentFrame == 0)
-					Sound.PlayRaw(video.AudioData);
-				advanceNext = false;
 				video.AdvanceFrame();
-			}
-			
-			if (dt > timestep)
-			{
-				lastTime = t;
-				advanceNext = true;
+				if (nextFrame == video.CurrentFrame)
 					videoSprite.sheet.Texture.SetData(video.FrameData());
 			}