DaySequerra Eclipse LBR4 - Manual (Page 6)

6
LBR4
User
Manual
Introduction
DaySequerra’s LBR4 Intelligent Low Bit Rate Digital Loudness Processor measures and corrects
perceived loudness of four stereo channels of program audio using the industry-standard ITU-R
BS.1770/1 and Eclipse Loudness Measure algorithms. This proprietary algorithm was developed by
after extensive research into human hearing and perceived loudness.
LBR4 is specifically designed to improve the audio performance of low bit rate HD Radio multicasts,
DAB and DRM channels with particular focus on stereo at 24 kbps.
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 Eclipse Loudness Measure 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 and correction over
time. It features the Eclipse Loudness Measurement technology to provide accurate loudness
measurements and newly developed psychoacoustic processing with look-ahead gain correction to
make audio level adjustments that are transparent to listeners. DaySequerra’s proprietary Eclipse
codec pre-processing engine has been specially tuned for operation at 24 kbps, 32 kbps, 48 kbps, 64
kbps, and 96 kbps bit rates to significantly reduce artifacts from lossy codecs and low-bit rate
transmission.
To improve system reliability and up-time, LBR4 uses a robust dual DSP-based processing platform
rather than the PC-based approach to completely avoid broadcast disruptions caused by operating
system lockups. A set of user-definable alarms can alert an operator of input loss. An Ethernet
interface provides field software updates.