Orban Optimod-PC 1101, Operating Manual

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INTRODUCTION ORBAN MODEL 1101
to constrain the peak level of the digital signal feeding the D/A converter to
–0.5 dBfs or lower. For this reason, it is wise to set OPTIMOD-PC’s output level
control to –0.5 dBfs when driving linear PCM path that does not contain an audio
encoder. As discussed above, if there is a codec in the signal path, set OPTIMOD-
PC’s output level control to –3 dBfs or lower.
OPTIMOD-PC’s processing has a second output after the multiband compressor but
before the look-ahead peak limiter, which is where the majority of the delay occurs.
This output feeds one of the inputs to the output routing switcher in the Orban I/O
Mixer application.
When driven by the multiband compressor alone, the input/output delay is ap-
proximately 3-4 ms (depending on whether the analog or digital input is used and
whether sample rate conversion is used). This delay can still be uncomfortable to
some, but many DJ/presenters find it acceptable and almost anyone can get used to
it.
Such problems can be avoided completely if the DJ/presenter’s headphones are driv-
en directly from the program line or, better, by an inexpensive analog compressor
connected to the program line. If the DJ/presenter relies principally on headphones
to determine whether a digital radio station is on the air, simple loss-of-data and
loss-of-audio alarms should be added to the system. Such alarms could be config-
ured to cut off audio to the DJ/presenter’s phones when an audio or carrier failure
occurs.
Streaming and Netcasting Applications
This section was written in late 2011. As the state of the art in netcasting is changing
with ferocious rapidity, we expect it to become outdated quickly. Please check
Orban’s web site, www.orban.com, for newer information.
Using OPTIMOD-PC in Streaming Applications
You need an audio source connection (either analog, AES3 digital, or S/PDIF digital).
The digital input can accept any sample rate from 20 to 96 kHz. You can also use any
stream available within the computer’s internal WAVE audio system, such as a digi-
tal playout system.
One of the outputs of OPTIMOD-PC’s routing switcher sends audio back into the
computer’s internal WAVE audio system. You will ordinarily connect this stream to
the input of an encoder application, like Orban OPTICODEC-PC Streaming Encoder,
RealNetworks Real/Helix Producer, or Microsoft Windows Media Encoder running on
the same host as OPTIMOD-PC. You then apply the encoded output of the encoder
to a netcast server application, which may operate on the same machine as the en-
coder, or on a different machine on your network. In the latter case, you will route
the encoded audio to the netcast server application through your network. (See
Processing for Audio Codecs on page 3-6.)