Harmonic Electra 1000, Installation Manual

Page: 13 / 71

Chapter 2 Introduction Audio Encoding Features
© 2012 Harmonic Inc. 13 Electra 1000, Version 3.0, Rev M
2.4 Audio Encoding Features
Table 2-3 describes audio encoding features supported by the encoder.
2.5 DiviTrackIP Support
DiviTrackIP statistical multiplexing provides high-performance video compression when
multiple channels share a specified bandwidth. The system maintains the overall pool
bandwidth at a constant bit rate while allocating to individual channels the optimum number
of bits on a frame-by-frame basis, driven by picture complexity information from the
LookAhead™ analysis. By assigning priorities, you can specify channels that must maintain a
high quality when stress on the system increases.
The Electra 1000 encoder works in conjunction with NMX and a ProStream™ 1000 to
support DiviTrackIP. The ProStream 1000 analyzes the complexity of all incoming video
streams and sends messages to the encoders through the IP network. All streams from an
Electra 1000 encoder must be sent to the same ProStream 1000. MPTS (multiple STC clocks
per chassis) is also supported.
Table 2-3: Audio Encoding Features
Feature Support
Stereo pairs

Up to 10 stereo pairs

Two stereo pairs per audio input card
Input format

Digital: AES3 or S/PDIF

Analog: balanced or unbalanced
Analog reference
level specification Reference levels in the range -10 dBu to +4 dBu may be specified
in 0.5 dBu steps. Alignment tone at reference level is placed at
-20 dBFS per SMPTE RP155.
Audio encoding
format

MPEG-1 Layer II (stereo) compression, and passthrough (digital
input only; embedded audio not supported)

Analog and digital

Single channel, dual, stereo, and joint stereo

Single PID per channel support with MPEG-1 Layer II
24 bit audio
sampling resolution Supported
THD+noise 0.0032% measured at –3bBFS
Audio sampling
frequency Up to 48 kHz
Input adapter gain
structure Tied to standards and industry practice
Compliant VBV Disable function supported for the audio-video buffer verifier to
allow larger buffer size
Single PID per
channel

Supported for MPEG-2 Layer II audio compression

Allows two audio circuits per adapter port for up to 20 mono
channels