Chapter 6 Audio Modules
AHC-561 Module
© 2015 Harmonic Inc. All rights reserved.
60
Electra 9200, Rev O
Connecting the AHC-561 Audio Input Cables
Connect a coaxial cable with BNC connectors from the digital audio port to the audio source:
n
On the encoders, the digital audio ports are DGTL AUD1, DGTL AUD2. DGTL AUD3, and
DGTL AUD4.
n
For multi-channel audio, use three cables to connect the surround mix, connecting L/R to
DGTL AUD1, C/Lfe to DGTL AUD2, and Ls/Rs to DGTL AUD3, which maps the channels
to AES3 pairs as defined by SMPTE 320M.
AHC-561 Audio Encoding Features
The AHC-561 modules accept discrete AES3/SPDIF digital, or AES3 embedded in HD/SD
serial digital video inputs. For discrete AES3 inputs, sampling frequencies of 48 kHz, 44.1
kHz, and 32 kHz are supported. Embedded in digital video is supported only for 48 kHz
sampling, which must be synchronous to the video.
Dolby Digital Metadata with the AHC-561
Dolby Digital signals include metadata describing the contents of an audio stream. The
metadata can assist the decoder in adjusting listening volume, downmixing from multi-
channel to stereo, and other features. The metadata can be received via a serial stream
through the AHC-561's RJ-45 connector.
Section
describes the serial connection for this port.
Table 6–6: AHC-561 Audio Encoding Features
Feature
Support
Digital input
n
Digital multi-channel or multiple stereo inputs
n
One 5.1 surround plus one stereo pair, or four stereo pairs per
card (surround mix on three AES3 signals with channels
mapped per SMPTE 320M (L/R, C/Lfe, Ls/Rs)
n
Completely embedded audio extraction of twelve pairs from
six groups from serial digital video input (48kHz synchronous
to video only)
Input format
n
Digital: AES/EBU, S/PDIF, IEC60958
n
Embedded: from SDI (synchronous to video)
Audio encoding
format
n
MPEG-1 Layer II 2.0 (stereo) compression
n
AC-3 single 5.1 or 2.0 compression (one 5.1 and one 2.0
encoding simultaneously, or four 2.0 encodings
a
n
Dolby E to AC-3 transcoding
a
n
AC-3 metadata input connectors
a.
Requires an optional firmware license.
Extraction from serial
digital video (48 kHz
sampling only)
n
MPEG-1 Layer II
n
Select up to two pairs from any four groups
