here is the explaination from dolby themselves;
In a Blu-ray Disc player, soundtracks decoded from the disc, as well as audio elements streamed or downloaded from an Internet connection or generated internally in the player, are decoded as digital PCM signals. PCM is the format players use to perform all internal audio processing operations, including mixing. In the mixing stage, secondary audio, button sounds, streaming commentary, and other non-disc-audio are mixed with the primary 5.1 or 7.1 soundtrack from the disc. The result is the complete audio presentation as intended by the content creator.
The built-in decoding of these high-definition formats enables full playback compatibility with next-generation A/V receivers as well as earlier A/V receivers not equipped with Dolby Digital Plus and Dolby TrueHD decoders.
Depending on the model, Blu-ray Disc players can output internally decoded soundtracks as follows:
As a multichannel PCM signal via HDMI
As a multichannel analog signal via analog connections
As a Dolby Digital signal via a coaxial or digital connection*
Many Blu-ray Disc players offer the choice of all three.
A/V Receivers with Dolby Digital Plus and Dolby TrueHD Decoding
Advanced A/V receivers feature HDMI 1.3 inputs and built-in Dolby Digital Plus and Dolby TrueHD decoders. This enables the receiver to decode high-definition theatrical (primary) soundtracks transported in their native format directly from Blu-ray Disc players equipped with HDMI 1.3 and bitstream out capability.
HDMI 1.3 provides all the standard HDMI benefits, including a single-cable connection for both audio (bitstream and PCM) and video as well as the proper application of the receiver’s DSP postprocessing, including bass management.
In addition, decoding theatrical soundtracks in your A/V receiver can enable full 96/24 digital audio capability when it is not supported in the player. Your system will also be ready for Dolby Digital Plus and Dolby TrueHD signals from future set-top boxes, Internet audio and video sources, and downloadable HD media devices.
this is from the Dolby web site. the only advantage i can see it that for the newer AVR, the AVR can enable the full 96/24 digial audio capabilty.. that's about it. I have a PS3 and i believe that it does support 96/24digital audio, so....in conclusion, after reading this, bitstream out or PCM.. is about the same. that means that last night, the dark knight (no pun intended)was played back at lossless audio. congrats.
