Something that would need to be fixed on some day Maybe we would need to strect the subtitle bitmap (720x576) to match excatly the whole video area.
We just need to pass the destination rectangle used in PlaneScene to our SubtitleRenderer.Render method, and then stretch the bitmap to that rectangle ( because as you say, thats the actual video area). Its not hard to fix actually, but in the long run we might want to make the SubtitleRenderer a real seperate rendering 'layer' so that it doesnt need to be referenced in PlaneScene.