DaySequerra NLC5.1ST - Manual (Page 7)

NLC5.1ST User Manual
7
Introduction
Broadcasters need a solution to effectively measure, and ultimately control the abrupt changes in
loudness that sends viewers diving for their remote controls during commercial breaks and action
scenes. The DaySequerra NLC5.1ST surround loudness control simultaneously measures the
perceived loudness of 5.1 surround program audio along with 2.0 auxiliary stereo using the industry-
standard ITU-R BS.1770/1 loudness measure or the DTS-Neural Loudness Measure (NLM) algorithm.
NLC5.1ST then uses the proprietary DTS-Neural Loudness Control, an advanced loudness leveling
algorithm, to apply the appropriate gain or attenuation to maintain the broadcaster-defined loudness
level. The resulting audio has a naturally open, dynamic quality without the annoying side-effects of
traditional energy-based volume management solutions.
Loudness is a perceptual property of an audio signal when it is reproduced acoustically. It is a complex
non-linear function of amplitude, frequency and bandwidth. Current audio level meters measure the
level of audio signals expressed as the amplitude of the signal - either the RMS (root mean square)
voltage of an electrical signal or the sound pressure of an acoustical signal. Neither of these
measurements, although widely accepted, provides accurate indications of how viewers will perceive
the loudness of the audio programming.
The DTS NLM algorithm uses a perceptual model of human hearing to more accurately detect spectral
and density differences, inter-channel relationships and temporal overlaps in any audio content,
resulting in a more accurate perceived loudness measurement over time. This proprietary algorithm
was developed by after extensive research into human hearing and perceived loudness.
To improve system reliability and up-time, NLC5.1ST uses a robust DSP-based processing platform
rather than a PC-based approach to completely avoid broadcast disruptions caused by operating
system lockups. An Ethernet interface provides long-term logging and field software updates capability.
An optional factory-installed HD/SDI module will allow for measurement of 8 channels of program audio
from group 1 or group 2 with user specified mappings within the group. A set of user-definable alarms
can alert an operator of input loss, signal clipping and high or low signal levels referenced to the
desired loudness level.
When NLC5.1ST is used ahead of an AC3 (Dolby Digital) transmission, the target loudness level will
also match the Dialnorm metadata information, thus providing consistent, enjoyable audio for all
viewers.
Whether pre-screening content at an ingest point or controlling the loudness of a broadcast air-chain,
the DaySequerra NLC5.1ST is your key to reduce viewers complaints and improve audience
satisfaction.