devices should also benefit from incorporating
these into the aggregate signal.
Finally, Teradek’s Landman points out that
all providers in the space are agnostic as to the
cell signal, since the key technology is how efficiently they can mux them together. So supporting new technologies should occur soon after they become relevant.
Choosing a Vendor
All of this has been interesting (I hope), but
you’ve probably read this article to assist with an
upcoming buying decision. So here is some specific advice for that. Step 1 is always to plot out
how you’ll be using cellular bonding, which can
range from simple, stream-to-Facebook-Live applications, to point-to-point video transmissions
to decoders in your studio, to more complicated
hybrid schemas that involve encoders, decoders,
and the cloud.
In particular, if you have existing encoders
that you need to use, you’ll want a transport-only solution. Recognize, however, that integrated encoding/bonding solutions may provide a
more-functional solution overall. That’s because
within an integrated solution, the encoder can
adjust the data rate of the encoded video upward
or downward to reflect the available bandwidth,
improving quality when bandwidth is plentiful,
but preventing dropped frames and stoppages when bandwidth drops. If you’re streaming
from a notebook running vMix into a modem-only solution, there’s no back channel for adjusting the encoded bitrate if bandwidth drops,
so you risk stoppages—or you’ll have to stream
at a less-aggressive data rate to avoid them.
Then assess product requirements like miniaturization or ruggedization to identify which
families of solutions can meet your needs. From
there, ask the following questions and take these
steps before buying a cellular bonding solution,
whether from one of the vendors included in
this discussion, or any other.
Recognize that there are multiple factors
that impact throughput beyond the speed of
the underlying cellular modems. Specifically,
the underlying technologies that differentiate
products from these companies include how ef-
ficiently they can bond together the signals, and
how fully they can utilize the bonded signal. All
companies also offer some form of error cor-
rection to maintain a robust signal when pack-
ets are lost. As you’ve learned, cellular bonding
systems use different codecs, including H.264,
H.265, and Streambox’s ACT-L3 codec.
All of these factors impact the bandwidth
necessary to transmit a sufficiently high-quality
video signal, and they impact each device’s ability to maintain that bandwidth. The best way to
figure out how a particular device will perform in
your area is to ask producers who are already using it. While you’re at it, you should ask how many
modems they’re using, and from which provider.
• What’s the minimum functional bitrate?
While it’s probably not relevant in most
regions in the U.S., minimum bitrate becomes
critical in many other countries. If you’ll
be operating outside of the U.S., this is one
number you need to know.
• What’s the available cloud functionality?
When you choose a cellular bonding
modem, you’ll likely also be buying into the
cloud solution offered by that company. So
understand what you’ll need from the cloud
before buying the hardware, and understand
what it will cost, particularly if you’ll use
the cloud service to transcode from HEVC
or ACT-L3 to a format your target CDN or
social media service can accept.
By this point, most cloud services should be
able to remotely update, configure, and control
their encoders, provide previews of all streams,
route streams to multiple points (including social media services), and archive the streams. If
your usage will be primarily local or regional,
most cloud services should work well. However, if you’ll be routing signals around the globe,
you should understand whether the cloud service has the infrastructure and protocols to efficiently support this.
Take these steps, and follow the guidelines
provided within this article, and you should be
able to configure, acquire, and use a functional
system that reliably gets your signal up to the
cloud, and to multiple output points from there.
Jan Ozer ( firstname.lastname@example.org) is a streaming
media producer and consultant, a frequent contributor to industry
magazines and websites on streaming-related topics, and the
author of Video Encoding by the Numbers. He blogs frequently at
Comments? Email us at email@example.com, or check
the masthead for other ways to contact us.