GUIDE TO INSTALLATION AND OPERATION
22
| HCO-3901
Note that when the ALC option is active but clean switch is not active (either the option has not been purchased, or is
available but not activated), the reference source is forced to the selected input. The user can select a different
reference here, but that selection will only become active when clean switch is activated. In this case, a warning
message will appear in the panel.
3.4.7 The Audio Embed panel
SD Audio Embed Input 1 & SD Audio Embed Input 2
Use the pulldown to select the number of audio bits to be
embedded at the output from these inputs.
Audio is processed in the HCO-3901 according to the
following rules:
1. Supported serial formats include
o
SMPTE-299,
o
SMPTE-272M-C (Embedded audio)
2. When switching PCM audio, a fade-out / fade-in is
performed on a few samples to avoid audio glitches.
3. When switching Dolby-E and AC-3 audio, no fade-out /
fade-in is performed. For Dolby-E, the channel switches
on the video switching line (i.e. between 2 packets).
4. Audio embedding is 20 or 24 bits (only for SD inputs).
5. 16 channels per input are supported
6. Note: These controls are disabled when clean switch is
disabled and the ALC option is not enabled. In this case,
the HCO-3901 acts as an intelligent 2x1 router.
3.4.8 The ALC panel
Minimizing loudness differences between segments in a playout channel is an important issue in a world where
multiple programs originating in different formats from different sources must be integrated seamlessly. The Automatic
Loudness Control (ALC) option is the solution to this need. It uses Grass Valley’s proprietary
wideband
ALC
algorithm.
•
Identified as HCO-3901-OPT-ALC-X, where X can be 2, 6, 8 or 16 input channels. The table shows the ALC
models available :
Model
Description
Output Channel Config.
PGM 1 & 2
PGM 3-8
HCO-3901-OPT-ALC-2
2-Channel ALC, up to 2 programs
Up to 2.0
N/A
HCO-3901-OPT-ALC-6
6-Channel ALC, up to 8 programs
Up to 5.1
Up to 5.1
HCO-3901-OPT-ALC-8
8-Channel ALC, up to 8 programs
Up to 7.1
Up to 7.1
HCO-3901-OPT-ALC-16
16-Channel ALC, up to 8 programs Up to 7.1
Up to 7.1
Depending on the model, different channel configurations are possible as listed in the table above. The 2-channel
ALC supports only two independent programs (either one 2.0 program, or 2 mono programs). All other ALC models
supports up to 8 independent programs (mono channel, 2.0 channels, 3.0 channels, 4.0 channels, 5.1 channels and
7.1 channels).
Figure 3.23 Audio Embed panel
