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Steven Sullivan · Guest

As I understand it (based on e./g. the first post in this thread:

http://www.avsforum.com/avs-vb/showthread.php?t=748147

)

Dolby Digital/DTS LFE channel info is recorded such that it expects a 10 dB boost at playback
(recorded 10 dB *lower* than the other channels, to allow for all those stomping dinosaurs and
exploding UFOs). All DD decoding receivers should apply this internally to the bitstreams.
This is part of the spec for the formats.

Question:

Does anyone know for certain what the respective specs (the equivalents of the Redbook
standard for CD) for SACD and DVD-A say about signals mixed to the LFE channel in each format?
Are they calibrated like DD/DTS LFE, to ultimately allow louder signals than the other
channels? Or is it just like the other channels?

And too, does anyone here know if there is a 'standard' for treament of PCM/DSD LFE via
digital connections such as HDMI? e.g from that AVSforum post

"SACD{/DVD-Audio?} over a digital interconnect:
This is unclear, and will depend on the digital interconnect type. Normally one would expect
digital output to be "raw". But what happens when the raw LFE doesn't need a boost, because
it's come from SACD (or DVD-Audio?)?

The full connection standards aren't publically available (eg CEA-861-D for HDMI). Is there a
standard for LFE level over these connections? If there is, then the standard would be that
LFE over digital interconnects should always need a +10dB boost at the receiver (as per ITU-R
BS.775-2 and ITU-R BR.1384-1). Then any player outputting SACD (or DVD-Audio?) data would have
to attenuate its LFE by 10dB so the receiver could still apply a 10dB boost, as it does for
DD+/DTS HD sourced data."

(This is also all impacting the new HD-DVD/Blueray audio formats such as DOlby TrueHD, which
are decoded in the players and digitally streamed to the AVRs as PCM, not bitstream. There
seems to be much confusion at the gear end over how to properly reproduce the HD audio LFE)

___
-S
"As human beings, we understand the world through simile, analogy,
metaphor, narrative and, sometimes, claymation." - B. Mason