Dolby Laboratories DP570 - Manual (Page 107)

A Guide to Dolby Metadata Parameter Definitions
Dolby ® DP570 Multichannel Audio Tool User’s Manual 95
Channel parameter can be set. You must have at least three channels to be able to add an
LFE channel.
Bitstream Mode
This parameter describes the audio service contained within the Dolby Digital bitstream.
A complete audio program may consist of a main audio service (a complete mix of all the
program audio), an associated audio service comprising a complete mix, or one main
service combined with an associated service. To form a complete audio program, it may be
(but rarely is) necessary to decode both a main service and an associated service using a
maximum total bit rate of 512 kbps. Refer to the Guide to the Use of the ATSC Digital Television
Standard, Document A/54 for further information. Although a detailed description of each
option follows, in practice, most programming uses the default setting, Complete Main. An
example of an exception to this rule is a special karaoke DVD, or an emergency service
within digital television.
Table D-5 LFE Channel Settings
LFE Channel Setting
Enabled
Disabled
Table D-6 itstream Mode Options
Bitstream Mode
Setting
Definition
Complete Main (CM) CM flags the bitstream as the main audio service for the program
and indicates that all elements are present to form a complete audio
program. Currently, this is the most common setting. The CM
service may contain from one (mono) to six (5.1) channels.
Main M&E (ME) The bitstream is the main audio service for the program, minus a
dialogue channel. The dialogue channel, if any, is intended to be
carried by an associated dialogue service. Different dialogue
services can be associated with a single ME service to support
multiple languages.
Assc. Visual Imp. (VI) This is typically a single‐channel program intended to provide a
narrative description of the picture content to be decoded along
with the main audio service. The VI service may also be a complete
mix of all program channels, comprising up to six channels.
Assc. Hear Imp. (HI) This is typically a single‐channel program intended to convey audio
that has been processed for increased intelligibility and decoded
along with the main audio service. The HI service may also be a
complete mix of all program channels, comprising up to six
channels.
Assc. Dialogue (D) This is typically a single‐channel program intended to provide a
dialogue channel for an ME service. If the ME service contains more
than two channels, the D service is limited to only one channel; if the
ME service is two channels, the D service can be a stereo pair. The
appropriate channels of each service are mixed together (requires
special decoders).