Bitstream & PCM

DocfosterDocfoster
edited December 2010 in Digital
I got an HD freeview box for Xmas.
Not a strict audio topic at first glance, but bare with me...
Gloucester is waiting till April for its digital switch over, but I thought the box would be something actually useful to put on the xmas list.
With big screen sport, HD (via HDMI) provides a massive improvement over SD broadcasts.

I made sure that I stipulated an HD freeview box with a digital audio output to feed my DAC.
Everything's connected up and working fine, and anticipating gloucester's spring switch from analogue to freeview HD.

In the meantime, i've been exploring the The HD box's audio capabilities. The setup menu allows one to switch digital audio output from 'bitstream' to 'PCM'. My limited understanding is that PCM is the more faithful mode of digital transfer. Can anyone shed any light on these 2 different signals?
Switching between the 2 produces a large difference in volume levels - bitstream is significantly louder. It also sounds more like bad-digital (swishy and compressed). Are these perceived qualities usual?

Ben

Comments

  • uglymusicuglymusic
    Yikes! That sounds confusing.

    PCM stands for Pulse Code Modulation, which I would have thought meant Digital Out in this context. And Bitstream is one kind of DAC technology, so I'd have thought that meant Analogue Out.

    But that doesn't sound like what's happening with your box, so this is a long and rambling way of saying 'I haven't got a clue!"
  • AlanAlan
    edited December 2010
    Dunno. ~:>
  • DocfosterDocfoster
    The bitstream/PCM choice effects the digital output (HDMI and coax).
    No biggie.
    Ben
  • uglymusicuglymusic
    There's always the eternal advice - RTFM  O:)
  • DocfosterDocfoster
    It's on a cd, and my laptop charger is broken so I can't view it at the moment (awaiting new one through the post).
    Will take a good look when i have some power.
    Ben
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