Just recently bought a PS3 and so fairly new to Blu Ray. Can someone explain what Uncompressed PCM audio is. I have a home cinema system so i use 5.1 DD. But I keep seeing this option in Blu Ray menus for 5.1 uncompressed PCM audio. What exctly is it and what do you need to listen to it? I selected it once and got no sound. Just wondering what the difference is between this and 5.1 DD.