LMn Manual

Using LM2n/LM6n
LM2n / LM6n Manual 13
Each LM6n log file is a simple text document
that can be opened in any text editor. You can
easily copy and paste the information from a log
file into other applications – e.g., into your e-mail
client.
Fig. 10.: A sample LM6 log file, opened in a text
editor
An LM6n log file will contain…
– plug-in version information in the header
section
– overall statistics (including start and end
time and Descriptor data as seen on the Stats
page)
– the actual Loudness log with one line per
measurement in the following format, with
data separated by tabs:
– Date
– Time
– Loudness value.
Universal Descriptors
and Dolby LM100
Unlike methods that measure dialog only, LM2n/
LM6n may be used with any type of audio –
which includes dialog, of course. If you wish to
measure dialog, it is recommended to do a man-
ual spot check of a program or a film. Find 10 to
30 seconds of regular dialog and measure it with
LM2n/ LM6n. Where dialog may be soft, regu-
lar or loud, and shift by more than 15dB inside
a film, regular dialog tends to be less ambiguous
and more consistent across a program.
For compatibility with a proprietary measure
such as Dolby LM100, only some of these meters
are updated to use ITU-R BS.1770 and Leq(K)
while others are locked at Leq(A). The software
version of LM100 should be 1.3.1.5 or higher in
order for it to comply with BS.1770, and to have
its average loudness reading be compatible with
Center of Gravity in LM5 or Program Loudness in
LM2n/ LM6n . Even used just on speech, Leq(A)
is not a precise approximation to perceived loud-
ness, so please update the unit to BS.1770 to
obtain similar readings and predictable results.
To measure dialog with LM2n/ LM6n the same
way Dolby LM100 is sometimes used, solo the
Center channel during a spot check to momen-
tarily disable the channel weighting specified in
BS.1770, if you’re working on a 5.1 stem.
Universal descriptors
and AC3 Meta-data
The “Dialnorm” parameter in AC3 metadata
should indicate the average loudness of a pro-
gram. Basic dynamic range and level control that
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 LM2n / LM6n is directly
compatible with Dialnorm in AC3. Most broad-
cast stations work with a fixed dialnorm setting,
for instance -23 LUFS. This would be the Pro-
gram 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.