Dolby Laboratories Multichannel Audio Tool DP570 - Manual (Page 99)

Dolby ® DP570 Multichannel Audio Tool User’s Manual 83
Appendix D
A Guide to Dolby Metadata
Metadata provides unprecedented capability for content producers to deliver the highest
quality audio to consumers in a range of listening environments. It also provides choices
that allow consumers to adjust their settings to best suit their listening environments.
In this document, we first discuss the concept of metadata:
• Metadata overview
We then discuss the three factors controlled by metadata that most directly affect the
consumer’s experience:
• Dialogue level
• Dynamic range control
• Downmixing
Finally, we define each of the adjustable parameters, and provide sample combinations:
• Individual parameters
• Metadata combinations
D.1 Metadata Overview
Dolby ® Digital and Dolby E are both data‐rate reduction technologies that use metadata.
Metadata is carried in the Dolby Digital or Dolby E bitstream, describing the encoded
audio and conveying information that precisely controls downstream encoders and
decoders. In normal operation, the encoded audio and metadata are carried together as a
data stream on two regular digital audio channels (AES3, AES/EBU, or S/PDIF). Metadata
can also be carried as a serial data stream between Dolby E and/or Dolby Digital
equipment. Metadata allows content providers unprecedented control over how original
program material is reproduced in the home.
Dolby Digital is a transmission bitstream (sometimes called an emission bitstream) intended
for delivery to the consumer at home through a medium such as DTV or DVD. It consists
of a single encoded program of up to six channels of audio described by one metadata
stream. The consumer’s Dolby Digital decoder reproduces the program audio according to
the metadata parameters set by the program creator, and according to settings for speaker
configuration, bass management, and dynamic range that are chosen by the consumer to
match his specific home theater equipment and environmental conditions.
Dolby E is a distribution bitstream capable of carrying up to eight channels of encoded audio
and metadata. The number of programs ranges from one single program (Program Config:
5.1) to eight individual programs on a single Dolby E stream (Program Config: 8 × 1). Each
program is discrete, with its own metadata in the Dolby E stream. Some metadata
parameters in a Dolby E stream automatically configure a Dolby Digital encoder at the
point of transmission, while others affect only the consumer’s Dolby Digital decoder
operation.