Internet Protocol Television (IPTV) is growing rapidly as a means for the delivery
of video content. Both hardware and software technologies are developing to
meet this demand, with a number of scalable solutions now hitting the market.
Video distribution has come a long way since the days of analogue distribution.
With the advances of MPEG-2, H.264 and now High-Efficiency Video Coding
(HEVC) compression, it has become possible to fit more services at higher quality
into traditional distribution mediums such as satellite, terrestrial and cable. At
the same time, significant improvement in available internet bandwidth to the
end user has led to the potential for thousands of live services to be made
available at anytime to a connected home.
The combination of shrinking the needed bandwidth per service with
compression and the rise in available internet bandwidth to the end user is
leading to significant growth in streaming media, thus enabling providers to
reach their customers easily with content.
While hardware compression solutions have been the core of linear delivery
networks, software compression solutions have historically been the core of
streaming media delivery networks. As linear and streaming services converge,
it makes sense to look at architectures that leverage the benefits of each
solution and reduce the potential drawbacks.
Hardware solutions work well for single linear feeds, and they can often be
adapted for streaming services if the design of the Application-Specific
Integrated Circuits (ASIC) or Field-Programmable Gate Arrays (FPGA) allow
encoding based on the number of encoded blocks rather than on a single video.
This design also overcomes any concerns with synchronisation between
encoders as they are all managed out of the same hardware architecture.
However, if there is a need for more than eight high-resolution profiles, it might
be necessary to span beyond a single encoder design, thereby adding
complexity in order to maintain synchronisation across encoders to support ABR
alignment.
Software compression solutions have been historically utilised almost exclusively
for streaming or on-demand services. To encode a service, a server would have
a video capture card and the software encoding for the various output formats
required. Such a solution provides a significant amount of flexibility as any
component of the software architecture can be upgraded and modified based on
the application needs. However, software compression solutions have not
typically been used for linear services due to performance and reliability
concerns in a server-based solution.
A method to have the best of both worlds is a software architecture married
with purpose-built hardware. Such a solution provides the flexibility of a
software solution for generalised tasks such as transport stream (TS)
processing and table manipulation, while offloading the computational
complexity of video encoding to attached hardware. By riding the
commoditisation of server hardware and the ever-increasing processing
capabilities, this architecture is able to provide the critical advantage of scale
and channel density for OTT networks.
Mixing of software and hardware for compression solutions can provide
significant density improvements, while also providing the flexibility of software
upgrades and easier development of new features. The addition of GPU-
assisted encoding can provide a two-and-a-half to three times improvement in
encoding density for H.264 encoding, depending on the efficiency of the
software. This is a considerable jump in performance and allows for significant
flexibility in how the codec is used for compression.
While GPUs provide additional capacity for encoding, they are still designed for
general-purpose computation, albeit for a specific instruction set that can be
useful for assisting H.264 and HEVC compression. An alternate proposal is to
utilise ASICs dedicated for compression on dedicated PCIe boards in a server.
The advantage of an ASIC solution is that it has purpose-built compression
hardware with low power utilisation, and high performance for encoding only. In
this model, you are able to use software to perform all of the TS processing and
rate control and ancillary features such as audio transcoding, while the ASICs
handle the heavy lifting of the video encoding.
Both a GPU and an ASIC-based architecture will increase the cost and power
utilisation on a per-device level. While they both will provide a reduction on a
per-service basis, with the ASIC solution having almost 10 times the density, the
savings are considerably more.
Streaming media viewership has undergone tremendous growth over the last
few years. With this growth, video quality and quality of service have increased
due, in large part, to improving internet access and advances in streaming
technologies such as ABR. These improvements have led to ever-increasing
encoding complexity over traditional linear services. The increase in encoding
complexity will only accelerate with the addition of HEVC and further need to
simulcast different resolutions and codecs to handle client compatibility.
While software encoding was key to the launch of streaming media, providers
need to look at architectures that scale with the additional complexity
requirements of their customers. Hybrid software and hardware architectures
are currently the best options to provide the lower cost and greater flexibility
and scalability needed to adapt to this changing market landscape.
