X-PLATFORM
October 2016
33
BBC R&D releases first version of Turing codec
The BBC Research and Development (R&D)
department has released the first version of
the Turing codec, an open-source software
codec compliant with the high-efficiency
video coding (HEVC)/H.265 standard.
According to a new technical paper from
BBC R&D, entitled The open-source Turing
codec: Towards fast, flexible and parallel
HEVC/H.265 encoding, the main driver for
the development of the Turing codec is to
support the distribution of 4K/Ultra HD
(UHD) content in eight and 10 bits per
component, 4:2:0 format and up to 60fps.
Designed to comply with the Main
and Main 10, the Turing codec features
low memor y consumption, advanced
parallelisation schemes and fast encoding
algorithms. The final goal, according to
BBC R&D, is to achieve a fast HEVC/H.265
expect. From mobile and over-thetop (OTT) video, these services are
also benefiting from HEVC/H.265
efficiency gains of up to 50%.”
Acknowledging the bandwidth
efficiency that HEVC/H.265 has to
offer, Cousins adds that employing
HEVC/H.265 also improves picture quality for live and file-based
content in not only 4K/UHD but
also HD and SD resolutions. “By
encoding existing bouquets of HD
and SD content in HEVC/H.265,
broadcasters and service providers are able to free bandwidth to
expand their delivery options, such
as in OTT and LTE-enhanced mobile video services,” he elaborates.
For example, Slovenia-based
teleport operator Satellite Tele
communications Network (STN)
has chosen Elemental solutions to
power the unified headend delivery
of broadcast and OTT TV content
in HEVC/H.265 to its subscribers.
STN has been employing
Elemental Live, a software-based
live video processing solution
managed by Elemental Conductor
— a video network management
system — to transcode channel
content in six different profiles
for adaptive streaming. To ensure
that reliability and security requirements for content delivery
networks (CDN) are met, profiles
are published on Elemental Delta
origin servers, where the CDN
can pick up the content for multiscreen OTT delivery.
software encoder suitable for a variety of
applications.
Some areas BBC R&D focused on included reducing the memory footprint and
the complexity of encoding stages, and
attention was also paid to evaluating the
impact of HEVC/H.265 tools on compression
efficiency and complexity.
According to Saverio Blasi, senior
research engineer at BBC R&D, video
transcoding is one of the biggest challenges
today in terms of the volume of data it handles, and of its vast demand upon computing resources. Thus, the Turing codec was
“designed from scratch to be as lightweight
as possible in terms of memory consumption to allow the cost needed for encoding
to be reduced”.
With the goal of defining a set of
Designed for OTT service providers,
the EyeQ video compression solution
delivers HEVC/H.265 performance
using existing AVC/H.264-based
codecs, says Keith Lissak, senior
director, Product Marketing, Harmonic.
To date, according to Cousins,
HEVC/H.265 is in widespread
tests and early developments
across a whole spectrum of applications including satellite directto-home (DTH), contribution,
OTT, video-on-demand (VoD)
and 4K/UHD broadcasts, where
bandwidth efficiency is required
alongside high picture quality.
However, he stresses that
one of the hurdles to widespread
HEVC/H.265 adoption remains
with set-top boxes (STBs), as operators face “massive and potentially”
expensive upgrades to newer STBs.
Therefore, Cousins suggests
employing a software-defined video approach that can support both
AVC/H.264 and HEVC/H.265
streams within a single mux.
requirements to guide the development
of the encoder, the Turing codec combines two features: An optimised software
framework composed by C++11 constructs
and assembly optimisations, as well as
advanced algorithms and coding tools,
to ensure efficient encoding of videos at
different quality levels under a variety of
conditions.
Some functionalities that the Turing
codec supports include: Encoding of
slice types I, P and B; configurable intrarefresh period; coding units (CU) sizes
and prediction units (PU) types specified
in HEVC/H.265; rate control; shot change
detection; and rate distortion optimised
quantisation (RDOQ).
Currently, the Turing codec supports
three speed presets — slow, medium and
This approach, he explains, will
allow operators to upgrade their
subscribers’ STBs by integrating
HEVC/H.265, without causing
disruption to existing services.
Harmonic’s Trow maintains
his stand that HEVC/H.265 is
currently the “only real choice”
for 4K/UHD distribution. “For SD
and HD broadcast and OTT services, operators may continue to
use AVC/H.264, due to significant
traction on the client’s player and
decoder side, although the bitrate
will be twice that of HEVC/H.265.”
At IBC 2016, Harmonic introduced EyeQ, a real-time video
compression optimisation solution that delivers viewing experiences on Internet-connected
devices while reducing OTT
bitrates. Keith Lissak, senior director, product marketing, Harmonic,
says: “EyeQ is a new enhancement
for the Harmonic PURE Compression Engine, which is a softwarebased encoding and transcoding
platform.”
Designed to improve quality of experience (QoE) for OTT
service providers, EyeQ uses an
existing AVC/H.264-based codec
to enable “a more consistent”
viewing experience with enhanced
video quality and less buffering
on constrained networks, and
increases the ability to reach more
consumers over congested mobile
networks.
“With EyeQ, operators can get
fast. Conducting different experiments using the Main and Main 10 profiles to access
the performance of the Turing codec, BBC
R&D found that the performance of the
Turing codec is “generally weighted towards
achieving higher compression efficiency”,
although the Main 10 profile only supports
the medium and fast presets.
Concludin