Dolby Laboratories Multichannel Audio Tool DP570 - Manual (Page 44)

28 Dolby ® DP570 Multichannel Audio Tool User’s Manual
Using the DP570 Features
4.7 Measuring and Setting the Dialogue Level
The dialogue level parameter, also known as dialogue normalization or dialnorm , is a vital
element in audio content creation. The proper dialogue level value ensures that the
consumer hears different programs at the same level. See
Section D.2 for a detailed
explanation of the dialogue level parameter. The dialogue level for each program must be
carefully measured and then appropriately set. This is easy using the control in the
Dialogue Level Set area of the DolbyRemote 570, shown in
Figure 4‐4 .
Figure 4‐5
Figure 4-4 Measurement Control Options
4.7.1 Identifying Normal or Average Level Program Segments
To set the dialogue level parameter, the first and most important step is selecting audio clip
samples that represent the average loudness level of the program content. Remember that
the dialogue level parameter establishes the level for normal dialogue in the program;
quieter and louder scenes tend to show higher or lower measurements than the correct
value. Using more than one clip is worthwhile particularly in programs that feature
characters with different vocal qualities. In programs without dialogue, such as a music
concert, sections of average level need to be identified.
With representative audio clips identified, you can use the DP570 to set the dialogue level
parameter. You can use either the software interface or the front‐panel buttons; for this
operation we describe using the software interface first.
4.7.2 Measuring the Average Loudness of Identified Clips
The measurement feature complies fully with ITU‐R Rec. BS.1770 Algorithms to Measure
Audio Programme Loudness and True‐Peak Audio Level. Measurement includes the addition of
two distinct measurement modes relating to the measurement period itself: infinite and
short‐term. This section describes the behavior of both modes.
IMPORTANT NOTE REGARDING MEASUREMENT ACCURACY:
Measurements are most accurate when they cover signals with similar spectra, such as
dialogue; the more similar the spectra, the more accurate the measurement. This is why we
recommend the use of ITU‐R Rec. BS.1770 measurements to provision the dialogue level
Note: These changes harmonize both the core measurement algorithm and the
measurement modes between the DP570, the LM100 Broadcast Loudness Meter,
and the DP600 Program Optimizer.