This is somewhat puzzling and I wonder members might have insight to provide.
I use the PS3 (SuperSlim) to access streaming services like Netflix, Amazon and Vudu with output via HDMI.
When I play a show on Netflix that is noted as SuperHD 5.1, when the stream starts, the Dolby Digital+ indicator lights up on my Pioneer AVR.
Yet when I play streams on Amazon or Vudu that are noted as being 5.1 the indicator does not light up. And I have the PS3 set to output bitstream. But even more puzzling is, those streams do sound like they are in 5.1 with discrete audio coming from each speaker. This is not Dolby PLII since the sounds are very discrete and positioned correctly in the sound stage.
Do Amazon or Vudu send down PCM 5.1 for their 5.1 titles on the PS3? On my Roku 2 box when I pay a Vudu title that is advertised as being 5.1 the Dolby Digital + indicator does come on.