Dolby Laboratories DP570 - Manual (Page 98)

86 Dolby ® DP570 Multichannel Audio Tool User’s Manual
A Guide to Dolby Metadata Dialogue Level
Special Parameters
There are professional parameters in the Dolby E bitstream that are not under direct user
control, such as Timecode and Pitch Shift.
Timecode
Dolby E bitstreams carry timecode information in hours:minutes:seconds:frames format.
Pitch Shift
The Pitch Shift parameter can be generated automatically by a Dolby E decoder to control
the Dolby Model 585 Time Scaling Processor. If the input to the Dolby E decoder is not at
normal play speed (as with varispeed or program play), then the Pitch Shift Code
parameter indicates the amount of audio pitch shifting required to restore the original
program pitch.
D.2 Dialogue Level
Dialogue Level (also known as dialogue normalization or dialnorm) is perhaps the single most
important metadata parameter. The Dialogue Level setting represents the long‐term
A‐weighted average level of dialogue within a presentation, Leq(A). This level can be
quantified with the Dolby Model LM100 Broadcast Loudness Meter.
When received at the consumer’s Dolby Digital decoder, this parameter setting determines
a level shift in the decoder that sets, or normalizes, the average audio output of the decoder
to a preset level. This aids in matching audio volume between program sources.
In broadcast transmission, the proper setting of Dialogue Level ensures that the consumer
receives a standard listening level, so switching channels or watching a television program
through the commercial breaks doesn’t require adjusting the volume. Using the same
standard for all content, whether conveyed by broadcast television, DVD, or other media,
enables the consumer to switch between sources and programs while maintaining a
comfortable and consistent listening level.
The proper setting of the Dialogue Level parameter also enables the Dynamic Range
Control profiles chosen by the content producer to work as intended in less‐than‐optimal
Lowpass Filter x
LFE Lowpass Filter x
Surround 3 dB Attenuation x
Surround Phase Shift x
a. Extended Bitstream Information parameters are shown in italics.
Table D-1 Profession and Consumer Metadata Types <~Figure>(continued)
Metadata Parameter Professional Consumer