Dolby Laboratories Multichannel Audio Tool DP570 - Manual (Page 108)

92 Dolby ® DP570 Multichannel Audio Tool User’s Manual
A Guide to Dolby Metadata
There are separate metadata parameters that govern the Lo/Ro and Lt/Rt downmixes.
Certain metadata parameters allow the engineer to select how the stereo downmix is
constructed and which stereo analog signal is preferred, but Lt/Rt is the default selection
in all consumer decoders. See
Parameter Definitions on page 92 for the definition of
individual parameters.
During downmixing, as we have seen, the adjustment of Dynamic Range Control
parameters is limited. Broadly speaking, the stereo outputs use the Line mode compression
profile while the mono signal uses RF mode compression. As with dynamic range control,
downmixing is ultimately dependent upon each consumer’s unique listening
environment.
While the engineer must optimize the multichannel mix for reproduction in an ideal
listening environment, it is also important to preview the mix in downmixing conditions
to ensure compatibility with different playback systems when selecting the downmixing
metadata parameters. These previews can be achieved in real time using the DP570
Multichannel Audio Tool.
D.6 Parameter Definitions
This section explains both professional and consumer metadata parameters in greater
detail.
Metadata parameters include:
• Universal parameters
• Extended Bitstream Information (Extended BSI) parameters
Extended BSI parameters are active only when both the producer chooses to use them and
the consumer’s decoder is capable of reading them. All decoders can successfully decode a
metadata stream without Extended BSI parameters, and Extended BSI parameters translate
seamlessly to decoders that read only universal parameters.
D.6.1 Universal Parameters
All universal parameters are supported by Dolby E encoders and decoders; all except
Program Configuration and Program Description Text are supported by all Dolby Digital
encoders and decoders.
Program Configuration
This parameter determines how the audio channels are grouped within a Dolby E
bitstream. Up to eight channels can be grouped together in individual programs, where
Note: Universal parameters include both professional and consumer metadata. Table D‐1
on page 85 distinguishes between professional and consumer parameters.