InBroadcast - May 2023 - 40

40
www.inbroadcast.com | Vol: 13 - Issue 5 | May 2023
InAudio
Processing for the future
of broadcast audio cont'd...
Lawo processing and mixing
systems used last year to live stream
immersive Dolby Atmos signals of
the Tomorrowland Festival
The recently released WorkflowCreator app
for Minnetonka's AudioTools Server
arranged on the basis of having
the control surface in the studio or
control
racks
room while the processing
are located in a separate
been applied to over-the-air (OTA)
broadcasts for more than a decade.
" Overall, broadcasters have things
well
in hand for their terrestrial
signals, " he comments. " What has
changed in recent years is the growth
in streaming platforms. Programming
streams to the same levels as OTA
and OTT content is fine if viewers
watch everything on the same device
- typically a TV set - but -23dB or
-24dB LUFS [Loudness Units relative
to Full Scale] isn't
loud enough
when watching on a mobile device,
especially in a noisy environment. "
Schindel notes that " most of the
major streaming platforms " have
now settled on -16dB, which puts
them closer to podcasts
(-18dB)
than OTA broadcasts (-23dB or -24dB
depending on region).
Streaming
has also brought new challenges in
terms of where audio processing is
carried out along the distribution
chain. " For pure terrestrial OTA
signals, those that go from a
transmitter over the air to an antenna
in the viewer's home, processing
is still one of the final stages in the
transmission path, " he explains.
" Those signals are generally very
well controlled in terms of loudness.
With MVPD [multi-channel
video
programming distributor] services,
Christian Struck, Lawo
such as cable and satellite, or OTT
delivery methods, things get more
complicated, primarily due to local ad
insertion, where the station's original
commercial content is replaced by
provider-specific inventory. Since
that occurs downstream from - and
independently of - the OTA signal, it
introduces the potential for loudness
shifts
if the inserted content isn't
properly managed. The same is true
for local stations that stream their
content, as online ads are often geoand
user-targeted and aren't always
as carefully produced or managed. "
Orban's main point of processing
is at the head-end, with the signal
going into the encoders and then on
to the output distribution paths. " All
the processing is done in the studio, "
says Peter Lee. " We make sure there
are no overshoots and that it
all
sounds good at very low bit rates. The
bit rates are so low today but people
want to broadcast stereo at a high
quality. So, if you're running AAC+
at 44kb/s through an OPTIMOD, you
can still get a fairly good hi-fi quality.
For television we have the OPTIMOD
1101s or the 6300, both of which are
used by many TV channels. "
The ability to process audio signals
in different locations on a network
is something that has long been
applied
through the programme
making stage of broadcasting. Many
audio mixing consoles
are now
apparatus area, which could be some
way away. Lawo is among the console
companies that has pioneered this
approach, starting with the mc² range
of desks and now further expanded
through the A__UHD Core.
" With this separation in place - and
provided both the console and the
processing core can communicate
with each other over IP - a signal
ingested in location A can be mixed
in location B, which actually means
the mixing commands
generated
there are executed by the DSP core
in
location
C, " explains Christian
Struck, Senior Product Manager for
Audio Production at Lawo.
" Open-standards IP furthermore
allows a given signal
transmitted
destinations
to a variety
processing.
Thanks
for individual
to multicast
streams, this no longer involves
analogue - or digital - signal
splitters. Depending on the expected
deliverable, it may be necessary to
tailor a mix to specific specifications
- such as
slightly
settings for the various loudness
formats. But do not expect as many
mixes as there are delivery formats:
this would run counter to the desire
to produce more with less. "
Lawo's
audio processing has
been software-based - running on
FPGA (field
programmable gate
array) hardware - since 2018. Struck
comments that, as well as this, " the
cloud is probably
everybody's mind " , although there is
still some uneasiness about latency
at the back of
due to the ingress and egress stages
involved. Kyle Wilken at Cobalt
Digital acknowledges that " a lot of
audio processing is now done in
software " but also highlights latency
as a consideration: " This is especially
the case for live production, which
means that dedicated on-premises
hardware is often still employed. "
Larry Schindel at Telos observes
software is now increasingly
that
either replacing hardware systems or
being used in conjunction with them.
" Processing for recorded content is
easily handled by software, such as
our Minnetonka AudioTools Server
platform, " he says. " It can be run on
a local server or in the cloud. Cloudbased
hosting is an attractive choice
for users who would rather not buy
and maintain their own hardware.
Processing in the cloud
is
to be
of
also
scalable, meaning it's easy to spool
up extra resources when needed.
" Managing loudness with software
also means
transmission-path
hardware-based
hardware
like
our Linear Acoustic AERO-series
processors don't have to work nearly
as hard,
allowing broadcasters to
differing LUFS
back off on the overall processing.
Real-time processing isn't
going
away, though. It remains necessary
for live local content and as an overall
safety net before transmission and
distribution. "
Today's audio processor may not
necessarily always be a reassuring
physical, hardware presence in the
control room or mixing suite but it
is now more essential than ever in
ensuring good sound quality and
consistent output levels across the
wide spectrum of distribution chains
that make up modern broadcasting.
Linear Acoustic AERO.2000 audio-loudness manager
http://www.inbroadcast.com
InBroadcast - May 2023

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