One year ago,
Radio World asked several experts to discuss trends in the broadcast
codec technology arena (Jan. 2, 2013). It was a popular topic, so we
return to it now to learn more and find out what’s new in a set of
four Q&As. Replies were via email and have been edited for
John Lackness is
VP Sales Americas for Tieline.
What’s the most
notable improvement in codec technology?
improvements to IP network infrastructure have led to broadcasting
over the public Internet becoming a new paradigm for many radio
engineers and even some codec manufacturers. Cost pressures and
demands to improve the bottom line have also driven broadcasters away
from leased lines, ISDN and satellite IP into terrestrial IP networks
for STL and audio distribution more generally.
Many engineers have
traditionally been concerned about broadcast reliability over
unmanaged IP networks, so I believe the most important recent
innovation in codec technology is the establishment of STL-grade
reliability over imperfect IP networks like the Internet. This is
achieved using codecs capable of dual redundant IP packet streaming.
simultaneously send redundant data streams from different Ethernet
ports. This delivers seamless redundancy by switching back and forth,
without loss of audio, from the nominated primary data link to the
backup link if one fails and then subsequently recovers. Using IP
links from two different IP network providers delivers optimal
redundancy over mission critical STL connections.
A number of other IP
strategies can work in tandem with this technology to optimize
reliability and audio quality; elements like forward error correction
(FEC) and automatic jitter buffering, which adjusts packet buffering
according to the prevailing health of the IP network at any given
of the art” in algorithms right now?
doubt the audio codec making the biggest impact globally in a
multitude of applications is the open-source codec Opus. Tieline sees
Opus as a game changer for the industry, just like MP3 was in the
1990s, and has added it to the Genie and Merlin codec families as
well as the Report-IT Enterprise smartphone app.
technology from the well-known SILK and CELT codecs and is adaptable
to both low-latency speech and high-quality music applications. As a
variable bit-rate algorithm it is ideal for a wide variety of
broadcast applications because of its capacity to deliver
high-quality, real-time audio over IP at low bitrates, and ultra-low
delay audio at higher bitrates.
Opus has been
ratified by the IETF and validated by the EBU, however development is
continuing in order to further improve the current implementation.
You released new
firmware in one of your codecs; why is it notable?
recent firmware release delivered four innovative new audio
distribution configuration options for Genie Distribution and Genie
Distribution WheatNet-IP audio codecs. These solutions were developed
as part of ongoing product improvement as well as customer feedback.
options include broadcasting 3 x bidirectional stereo connections, or
2 x stereo and 2 x mono bidirectional connections, or 1 x stereo and
4 x mono bidirectional connections, or 6 x mono bidirectional
connections. These solutions are ideal for broadcasters distributing
different programs from a single site to different IP addresses,
depending on the number of streams in use.
release due in early 2014 will allow these codecs to multi-unicast
three different stereo audio streams to up to 15 connections each, or
broadcast three separate stereo streams in multicast server mode and
distribute each of these streams to unlimited endpoints over
compatible IP networks.
new or features as we come into spring NAB season?
launches 2014 with the release of a new cost-effective,
high-performance, point-to-point and multi-point stereo IP audio
codec called Bridge-IT Xtra.
Bridge-IT Xtra is
recommended for low-cost studio-to-transmitter links (STLs),
studio-to-studio links and affordable remote broadcast links. The
codec has dual internal power supplies and supports six stereo
multi-unicast audio streams over the public Internet. You can also
combine Bridge-IT Xtra with Tieline’s Report-IT Enterprise
smartphone app to create a cost-effective, high-quality remote
algorithms include Tieline Music and MusicPLUS, LC-AAC, HE-AAC v.1
and v.2, AAC-LD, AAC-ELD v1 and v2, aptX Enhanced, MPEG Layer 2,
G.711, G.722 and MP3 playback. It also features an SD/SDHC card slot
for MP3 or linear audio backup.
if any, does the new AES67 standard have on you and your users?
new AES67 standard addresses the audio transport mechanism and the
clocking scheme required to achieve interoperability over competing
IP standards, but this is only part of the story.
technology partner Wheatstone Corp. was an active contributor to the
AES X-192 project group, which defined the AES67 standard.
WheatNet-IP equipment will be compliant with the standard; however
total interoperability also requires logic control for all peripheral
equipment at the control layer — elements such as routing control,
turning sources on and off, and gain control. This will require
agreement on additional standards for interoperability between
competing IP ecosystems.
with WheatNet-IP and Merlin PLUS with WheatNet-IP codecs will offer
AES67 interoperability via their onboard WheatNet audio card.
Assess the impact
of the decline in POTS, ISDN and other services.
is true that POTS and ISDN services are declining in importance
throughout the U.S. and parts of Europe as IP becomes the predominant
transport for carrying broadcast services. Drivers of this change
include the rapid improvements to wired and wireless IP
infrastructure and the cost advantages offered by IP networks. Telcos
are also influencing change by removing copper infrastructure in some
places and not installing new ISDN services in others.
and POTS services will coexist with IP for some time yet in many
regions, so flexibility is paramount. Engineers can choose broadcast
codecs capable of connecting over more than one audio transport,
which provides opportunities to connect over IP, ISDN or POTS as
required. This will assist as they transition to IP-only technology
over time, or allow them to integrate backup connections on
alternative transports should IP services become unavailable.
Do you foresee a
day when broadcasters don’t even need specialized “broadcast”
a perfect world of fiber to every premise, it is conceivable that
specialized broadcast codecs may no longer be required. However in a
world where terrestrial fiber is unlikely to be installed on such a
large scale any time soon, broadcast codecs are here to stay for the
Running fiber to
isolated STL transmitters over large distances with difficult terrain
presents other infrastructure challenges. Not to mention cost
considerations, and the integration of reliable backups over
alternative networks in case primary connections fail due to a
backhoe severing the fiber!
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