I have a Toshiba HD-A2 HD DVD player. In the setup menu it has the option for PCM or Bitstream. What is the difference and what should it be on? Every so often I think the player goes back the default settings and I can't get Dolby Digital sound. It goes to ProLogic. I can never figure out which setting it should be on. If anyone could explain this me I would greatly appreciate it.

What type of home theater receiver do you have? It should only be set to PCM if your receiver can handle it.

Its an older RCA surround sound receiver. If it should be on PCM, then what is Bitstream for?

Bitstream is any type of digital output, DD, DTS, PCM, whatever.

PCM is a particular type, Pulse Code Modulation like you'd get from a CD and is generally 2-channel stereo.

I tried to watch The Big Lebowski HD DVD today and on PCM it plays in prologic. On Bitstream it plays in Dolby Digital but it has no sound. Whats going on?

You want it on bitstream unless you had a newer receiver with HDMI. That is very odd that you aren't getting any sound, though. Did you make sure the audio options on the actual disc were set to dolby digital too? It could be defaulting to PCM and that is why you aren't hearing it. I am sure you do, but just in case, you also have either a coax or optical cable running from the A2 player to your receiver, right?

Optical cable. I played some regualar DVDs on Bitstream and everything was cool. HD DVDs are the only giving me problems right now. They used to be fine. Oh, well. I'll figure it out tomorrow. thanks

Bitstream is more than what X said above. It is the native signal off the disc. That is why DVDs work, since their DD/DTS is compatible with your receiver. HDDVDs might have newer codecs, if you use bitstream with these neither the optical connection nor your receiver can handle it. There ought to be a setting to output DTS via optical from what I read on these forums. The A2 will downconvert the newer codecs to DTS in this situation. That is probably your optimal setting with that equipment.