Uncompressed PCM 5.1 via Optical Link

[JayAuritt]

Okay, for many this might seem a stupid/elementary question, but for the technically-challenged like myself, it's something I need to know.

I have a PS3, connected to the TV via HDMI for video and to a receiver via Optical cable for audio. When I first set up the PS3 I chose the PCM option for audio, and was instructed later through one of the forum threads that I should have it set up as Bitstream, which I then did.

Now.....I just watched The Departed, selecting the PCM audio option on the disc rather than the Dolby Digital 5.1. My receiver indicated that 2 channels were being utilized, instead of the 5.1 channels I usually see when watching a DD or DTS disc.

Is this correct, and was I truly getting PCM 5.1 sound (it sure sounded good to me)? Or, in the case of watching a movie with PCM audio should I change the PS3 audio option from Bitstream to PCM?

I hope that makes sense.