https://issuu.com/newbayeurope/docs/tvte_june_2016/1
A 4K wireless link has been the missing piece in the live UHD workflow but developments at NAB shows the problem is being surmounted.
At
the risk of restating the obvious, 4K is four times the size of 1080p
video, which is a huge amount of data to transfer across a wireless
link. It’s a problem that has, and hasn’t yet, been solved. It’s
been solved in the sense that there are wireless 4K systems out there
but there's debate about the whether such systems are currently
practical.
For
Domo
Tactical Communications
(formerly Cobham) it’s all about making 4K production work, that
is, to get it on a screen properly. Latency is the primary issue,
especially for sports. Until the latency reduces, 4K will continue to
be a challenge, says Domo's broadcast sales director, JP Delport.
“For
example, if people are using H.265 algorithms to encode data, which
on paper is 50 per cent more efficient than H.264, there’s still a
heck of a lot of encoding going on, which by its nature increases
latency. Until such point that Domo can provide the industry with a
demonstrably usable 4K solution, we’re going to stick with 1080p.
4K can be done, and we’re working on it, but it will only be
unveiled when it’s absolutely ready at the lowest possible, usable,
latency.
There
are a variety of ways to bring 4K to TV screens in the RF domain.
Delport believes it will require the adoption of a new encoding
algorithm, which will be H.265 or HEVC.
“If
we want to do 4K in H.264 it’s possible that that amount of data
could be modulated with our MIMO (multiple input/multiple output)
technology over a wireless link. But it seems to me the obvious way
to go is DVB-T2 with an H.265 encoder, which is where we are heading.
Our current latency is one frame. Anything more than that would just
not be suitable for 4K. Until we’re 100 per cent sure that we can
have a 4K wireless camera at the side of a football field that has
one frame or less of latency, there’s no point.”
The
SOLO7-OB Tx camera-back transmitter is Domo's first 1080p60 solution.
It has integrated camera control and swappable RF modules. It’s
able to work at 4:2:2 chroma and does H.264/MPEG-4 AVC video
encoding. Its latency ranges from 1s to an ultra-low 10ms and fits
directly onto the back of an ENG type camera.
At
NAB this was demoed with a bi-directional link using MIMO IP Mesh
technology firing 26 Mbit/s in combination with a Sony HDC-P1 camera
mounted on a remote-controlled pan and tilt head. The unit takes
HD-SDI from the camera, encodes the audio and video data to IP, and
transmits it wirelessly to Domo’s MIMO IP Mesh system.
“Because
IP Mesh provides an exceptionally high bit rate for bi-directional IP
links, we can transmit A/V data one way while camera control and
remote control data travels the other for control of pan and tilt,
plus camera control data for colours, iris, etc. within the camera.
Typically, this would require three separate frequencies, but with
the SOLO8 SDR and IP Mesh combination, it’s three data streams in a
single bi-directional link, which makes the entire remote camera and
control system completely wireless. This, claims Delport, is a
genuine “first”.
The
data rate required to send 4K is about 19Gbps. “When you are trying
to compress that amount of data, all the issues related to
compression such as quality loss, added latency, and increase
susceptivity to errors are increased dramatically,” says
Uri Kanonich, vp, marketing, Amimon.
The
firm's Connex technology doesn’t use regular compression, rather a
unique video-modem solution. “This allows us to send today HD 1080P
signals with less than 1ms latency and the same chipset will allow to
do the same for 4K UHD,” says Kanonich.
The
Connex mini is the latest addition to the Connex range. Unveiled at
NAB, this is a ultra-small transmitter supporting 1080p, full HD
wireless video at a range up to 1500ft, ideal for airborne drones as
well as other unmanned systems.
“Drones
require the support of both high range and transmitter robustness,
adding to the already hard task of sending 4K. An additional critical
parameter is the mobility of the drone,” says Kanonich. “The
wireless link must be able to maintain the connection in all
directions and while moving.”
Amimon
previewed a solution for 4K straight from the lab. “The latency we
are already able to present is practically zero, and the quality is
just amazing,” claims Kanonich.
“The unit's size we envision to be the size of the Connex mini.
There's no need to increase size to support 4K UHD. But it will be
next year before we launch it in actual products.”
BBC
R&D's system
is completely bespoke using relevant parts of DVB-T2, DVB-NGH and
MIMO to maximise channel capacity.
“Having
extra bit-rate allows for lower latency video coding,” says project
engineer John Boyer. “The latency of the system is variable as
interleaving can be dialled in by the user to improve link
ruggedness, but the video coding is seven frames code/ decode delay.
We expect future coder developments to reduce that delay.”
The
UHD system uses extensions of an original HD version. “The new UHD
system has additional advanced RF techniques, so we are expecting
good performance and expectations are fuelled by range tests that we
have done,” says Boyer.
BBC
R&D is liaising with the industry to perform trials.
Vislink
is already providing what it says is the world’s first end-to-end
wireless 4K/UHD live-video solution. The UltraLite module is designed
for integration with existing UHD cameras, allowing customers to
quickly and cost-effectively upgrade.
“We know that being wireless creates new and different points of view for the audience and allows the cameraperson flexibility when capturing action shots from different moving points,” says Ali Zarkesh, VP, product management, Vislink. “It allows the viewer to really be there, and now they can do all that with UHD”
Vislink’s
system provides broadcasters with a simple upgrade path if they want
to move to a 4K/UHD wireless live solution. The firm says they can
upgrade existing cameras with the lightweight attachment that mounts
onto a variety of 4K cameras and, with the UltraDecoder (on the
receive side), they can use their existing wireless.
360-degree
wireless streaming
It's
well worth noting one other exciting new product launched at NAB,
designed for streaming
panoramic video and monitoring the results. Teradek's Sphere
features a patent-pending video processing platform for iOS and OSX.
Sphere’s hardware interface features four HDMI inputs and a
built-in H.264 encoder that can encode up to 10Mbps, providing a
“realistic 360ยบ-video experience.”
It
was paired with four GoPros at NAB and by adjusting each camera’s
white balance, tint, exposure and lens distortion in real-time,
Sphere is able to display and stream a consistent panoramic video. It
streams to Apple laptops and iOS devices over WiFi where users can
record or view live 4K (4x1080p) content as a pan
and zoom across all four video feeds stitched together; by moving the
iOS device the camera feed moves with it and on VR headsets.
For
remote viewing, the Sphere app can be used to live stream to any
compatible 360-degree online video platform, including Wowza and
YouTube.
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