Hartnett: Trends in Codecs
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 length.
we talk with Comrex Technical Director Tom Hartnett. Watch the
website for the rest in the series.
the most important recent change or improvement in broadcast codec
The innovation in the telecom world to include “HD Voice”
modes in non-broadcast products. Mobile phones, business desktop
phones and softphone apps now all consider “telco quality” audio
to be outdated, and are adding in high-fidelity codecs. Skype’s
been doing this for years. Nobody is better positioned to benefit
from that than radio. You just need studio hardware that can talk the
“state of the art” in algorithms?
AAC-ELD is still the winner for remotes and will continue to be
for some time, as it provides the perfect balance between low network
usage and low delay.
its heels is Opus, which has only a slightly inferior sound but a big
benefit for the telecom world in being free (as in speech and beer).
Opus is being adopted quickly by Web developers. For non-delay
intensive application (like streaming) HE-AAC is still king.
good are low-bitrate codecs, and how much better can we expect
performance to get?
The algorithms themselves are “good enough” now for the vast
majority of applications. Innovation in this field has moved to
things like error resiliency and variable bitrate operation on poor
relevance does the new AES67 standard have?
It’s early, and the new standard doesn’t include important
elements like presence and discovery. So it’s not perfect. But from
a product developer’s point of view it now opens up opportunity in
more pure-software products. Most hardware codecs consist of analog
and digital audio I/O tied to some type of internal computer. If we
can now support the audio side via Ethernet (and remain AoIP
vendor-agnostic), we can look at removing the custom hardware element
completely and go pure software on a server. Especially for products
that support lots of audio I/O channels, the idea of removing
handfuls of large XLR connectors is very attractive. Of course, this
only holds true for the studio side of any link, since field
broadcasts are still tied to old-fashioned analog for now.
the impact of the decline in POTS, ISDN and other older services on
It can be frustrating for a broadcaster to have to change his
paradigm, and expensive to buy new gear. But in the case of IP, it
comes with one pretty cool feature that can be quite enabling:
wireless over 3G/4G. If 4G coverage is good (and you’re not trying
to cover an event with thousands of mobile phone users present), this
becomes the ultimate broadcast tool — completely portable with zero
setup, no installation cost and great audio. And 4G networks are
getting better deployed every day.
is your newest product or notable feature?
Our BRIC-Link Product, which is our entry-level simple hardware
codec, is a huge seller for us. One of the many notable features of
this box is the ability to push an Icecast-style stream to your
webstream hosting company. We’re enhancing that aspect of the
product by supporting an HTTP push mode that delivers FLAC (lossless)
compression. This way the streaming company gets a perfect signal to
start with before compressing to MP3 or AAC, eliminating any lossy
transcoding. BRIC-Link can even act as a small-scale streaming server
itself, delivering dozens of HE-AAC streams to listeners using web
advances in consumer audio and IP infrastructure, do you foresee a
day when broadcasters don’t even need specialized “broadcast”
codecs to move high-quality audio around?
We find that even when a consumer-grade product starts to shadow
our offerings, many broadcasters will still need to rely on pro-grade
gear with solid support. I’m thrilled that budget broadcasters are
using Skype and similar stuff for remotes — first off, because I
believe local presence is such an important aspect of the radio
business, and cheap ways of achieving that makes radio better; but
also because when they hit a certain threshold of success, they’ll
call us for the “good stuff.”
more important element in providing “codecs to consumers” is the
ability for listeners to connect to the station in high fidelity.
This is something we’re aggressively promoting with our STAC-VIP
talkshow system. Radio will sound so much better when everyone calls
in using codecs!
has spent a lot of time and resources on the video side of the
industry. Will we see more of that?
Our LiveShot product does for video what we’ve done for audio,
but that doesn’t make it a TV-only product. We’re finding the
line is blurring, and it’s not an either/or thing. Radio stations
are making the transition from audio providers to media providers via
the Web, and often via cable TV.
also a nice side effect of all the video development we’ve done in
recent years. It turns out moving video over 4G networks is a lot
more challenging than audio, due to the tenfold increase in network
required. But we’ve licked that, and now we’re busy backporting
all the R&D we’ve done to make our audio codecs more resilient
on bad networks.
else we should know?
At the risk of sounding a bit cagey, I’m really excited about
the work being done by Web companies like Google in integrating
real-time, high-quality media streaming into their products. I can
see this stuff being available on every browser and on every computer
or smartphone soon, and it gives radio an opportunity to forever rid
itself of poor-quality telephone audio. We’ll be talking a lot more
about that in 2014.
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