Model DP569 User’s Manual Metadata
A–19
Surround Phase Shift
This parameter causes the Dolby Digital encoder to apply a 90-degree phase shift to
the surround channels. This allows a Dolby Digital decoder to create an Lt/Rt
downmix simply. For most material the phase shift has a minimal impact when the
Dolby Digital program is decoded to 5.1 channels, but provides an Lt/Rt output that
can be Pro Logic decoded to L, C, R, S, if desired. However, for some phase-critical
material (such as music) this phase shift is audible when listening in 5.1 channels.
Likewise some material downmixes to a satisfactory Lt/Rt signal without needing this
phase shift. It is therefore important to balance the needs of the 5.1 mix and the Lt/Rt
downmix for each program.
Surround Phase Shift
Setting
Enable (default)
Disable
A.5.2 Extended Bitstream Information Parameters
In response to requests from content producers, Dolby Laboratories recently modified
the definitions of several metadata parameters from their original definition as
described in ATSC document A/52. The original parameters were rarely, if ever used.
The revised definitions allow more information to be carried about the audio program
and allow more choices for stereo downmixing. When the metadata parameters
carried in Dolby Digital were first described, they were generically called Bitstream
Information or BSI. We refer to the alternate parameter definitions as Extended BSI.
Because the revised definitions affect metadata parameters that were not used by the
consumer decoders, all decoders will be compatible with the revised bitstream. Newer
decoders that are programmed to detect and decode the new parameters will be able
to implement the new features the Extended BSI provides.
Products that allow emulation of the effects of metadata, such as the DP570, normally
have a feature that allows emulation of a new (or compliant) decoder or a legacy decoder.
Preferred Stereo Downmix Mode
This parameter allows the producer to select either the Lt/ Rt or the Lo/Ro downmix
in a consumer decoder that has stereo outputs. Consumer receivers are able to
override this selection, but this parameter provides the opportunity for a 5.1-channel
soundtrack to play in Lo/Ro mode without user intervention. This is especially useful
on music material.
Preferred Stereo
Downmix Mode Setting
Not Indicated
Lt/Rt Preferred
Lo/Ro Preferred