Dr. Deepen Sinha
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
Here, Dr. Deepen
Sinha, CEO of ATC Labs. Watch the website for the rest in the series.
What’s the most
important change in codec technology that radio organizations should
IP codecs have now come of age and are finding broad acceptance, both
for remote broadcasting and STL applications. Moreover, now it
possible to not just do a two-way session with a reporter in the
field but also create a high-fidelity conference involving multiple
reporters scattered all around the globe using a flexible mixture of
hardware and software IP codecs.
quality soft codecs means you can deliver one to a reporter half-way
around the globe in seconds and have him or her be set up to do a
remote within minutes!
What is the
“state of the art” in algorithms?
think there are two to three parallel evolutions.
First is in the
field of conventional transform codecs, which have relatively high
latency (> 30–50 ms); and these can provide broadcast-quality
stereo audio in the 32–48 kbps range. Second is in the field of
codecs with algorithmic latency of 23 ms or so, which can provide
excellent audio at 80–128 kbps. And finally a third evolution is in
the field of ultra-low-delay
which have algorithmic latency of 2 ms or lower and provide
high-fidelity audio at 128–192 kbps/channel.
You have a unique
background in audio compression including personal involvement in
AT&T Bell Labs, Lucent, the PAC codec and iBiquity Digital. How
good are low-bitrate codecs, and how much better can we expect
performance to get?
low-bitrate codecs are now good enough for a lot of applications, but
I strongly feel that there is more to come, primarily given that
memory such as flash memory has improved dramatically in terms of
access time and is rapidly coming down in cost.
This opens up
several interesting possibilities for codec researchers, who even til
recently have had to make major algorithmic tradeoff to keep the
memory budget — particularly for a consumer end device. Back in
Bell Labs in the 1990s, I had caught some flak from colleagues for
stating that 8000 bps is a large number and 2 power 8000 represents
an incredibly large number of possible audio waveforms that can
be represented using these many bits in a second. What it really
meant was that if we had access to a very large memory, that could be
used to build dictionary-based coding, opening up hitherto unthought
Is there a danger
that our audio content is relying too much on compression?
codec developers and vendors should probably not oversell
compression. With the evolution in subjective testing methodologies,
it is possible to make fairly low-bitrate codecs look good through
suitable choice of testing methodologies. We often get a question,
“Why should I stream at 64 kbps or even 32 kbps when codec X in
such-and-such test was shown to be CD-quality at 24 kbps or 20 kbps?”
Our recommendation typically is that you also have to take into
account subtle artifacts — which become not so subtle over extended
listening — long-term listenability, listener fatigue and tandem
For a variety of
reasons it is still very much better to use a lesser amount of
compression if practical for a specific situation.
What is your
company’s newest product or notable feature?
introducing a powerful server-based studio IP codec called ALCO
which can simultaneously support 12 active call-groups on a 1U
server. This works with a network of our IP soft codec product ALCO
and recently introduced hardware IP codec ALCO
does the new AES67 standard have for you and your users?
standards in enterprise-level IP studio audio infrastructure are
obviously of great interest to us and our users. Let’s give it some
time and see how things evolve; but one should definitely keep it on
the radar screen.
Many people have
expressed concerns about the radio industry’s health and outlook.
What’s your take?
do not think I am qualified to comment on the latest economic
scenarios in the radio industry. But just from a technology
perspective, I think the industry now has access to exciting tools
and products that can allow broadcasters to really expand their wings
in terms of being able to constantly bring fresh new content from
virtually anywhere in the world and also be able to reach targeted
new audience and niche listenership, once again virtually anywhere in
Comment on this
or any story. Post below.