TC Electronic DB4 MKII - Manual (Page 88)

LM6
84 DB4 / DB8 MKII Algorithms
rely on this parameter may take place in the con-
sumer’s receiver. Therefore, its value should not
be far off target, or the consumer results become
highly unpredictable.
Program Loudness in LM6 is directly compatible
with Dialnorm in AC3. Most broadcast stations
work with a fixed dialnorm setting, for instance
–23 LUFS. This would be the Program Loudness
target level for any program.
If your station is more music than speech, better
inter-channel leveling may be obtained with dial-
norm permanently set 1 or 2 LU lower than the
Program Loudness target level.
True-peak meters
The peak meters of LM6 display true-peak as
specified in ITU-R BS.1770. True-peak meters
give a better indication of headroom and risk
of distortion in downstream equipment such as
sample rate converters, data reduction systems
and consumer electronics than digital sample
meters used e.g. in CD mastering. Note that the
standard level meters in most digital worksta-
tions and mixers are only sample peak (Final Cut,
Avid, ProTools, Yamaha etc.), and should only be
used as a rough guideline of the headroom.
Note that the meter scale is extended above
0 dBFS. Most consumer equipment distorts if
you see readings above 0. It’s not a problem to
have true-peak level going to -1 dBFS in produc-
tion, but legacy platforms (analog, NICAM etc.)
and some data-reduction codecs may distort
unless true-peak level is kept lower. With Dol-
by AC3 and with low bitrate codecs, -3 dBFS
should be considered the limit, while legacy plat-
forms requiring emphasis may need even fur-
ther restriction. Like described in EBU R128, it’s
recommended to make full use of the headroom
with true-peaks going to -1 dBFS in production,
and to only restrict peak level further during dis-
tribution/transmission.
LM6 algorithm – main page
LM6 algorithm – main page
Descriptors 1 and 2
Loudn. Range
Loudness Range, standardized in EBU R128 and
abbreviated “LRA”, displays the loudness range
of a program, a film or a music track. The unit is
LU, which can be thought of as “dB on the av-
erage”.
The Loudness Range descriptor quantifies the
variation of the loudness measurement of a pro-
gram. It is based on the statistical distribution
of loudness within a program, thereby excluding
the extremes. Thus, for example, a single gun-
shot is not able to bias the LRA number.
EBU R128 does not specify a maximum permit-
ted LRA. R128 does, however, strongly encour-
age the use of LRA to determine if dynamic treat-
ment of an audio signal is needed and to match
the signal with the requirements of a particular
transmission channel or platform.
Consequently, if a program has LRA measured
at 10 LU, you would need to move the master
fader +- 5 dB to make loudness stay generally
the same over the duration of the program. (Not
that you would want that).
In production, Loudness Range may serve as
a guide to how well balancing has been per-
formed, and if too much or too little compres-
sion has been applied. If a journalist or video
editor isn’t capable of arriving at a suitable LRA,
he could be instructed to call an audio expert
for help.