BEYOND HDMI: OTHER AV TECHNOLOGIES
Many AV technologies are competing for the position of
“best media transport system.” While HDMI is certainly
the current leader in connecting high-definition AV
equipment, there are a number of other technologies
that are relevant and may even play a dominant role in
content transport between devices. Below is a quick look
at several of these technologies:
Video Over Ethernet
HDBaseT uses a proprietary method for packetizing
high definition signals for transport over Category cable.
HDBaseT packets cannot be directly transported over
an Ethernet network or switched by standard Ethernet
switches. However, technology for packetizing the signal
directly into standard Ethernet frames is rapidly evolving.
Video over Ethernet (also called Video over IP) enables
the transfer of high definition signals directly on Category
cable networks using standard Ethernet switches.
The desire is to serve high quality high definition
video signals on the same network that provides data
connectivity. However, there are challenges to accomplish
this. HD video transmission requires significant bandwidth.
This bandwidth must be allocated to the AV stream
because, unlike data connections where bad packets can
be retransmitted, the AV stream is “real time” and is not
tolerant of significant error correction or packet retransmission
and latency like a normal data Ethernet transmission.
This leaves several issues to resolve:
• How to reduce the bandwidth required via
compression or other techniques.
• How to allocate or prioritize bandwidth for
sensitive AV streams for uninterrupted smooth
and synchronized audio and video.
• How to design and support an efficient and
cost-effective Ethernet network that can support
the combined data and AV bandwidth demands.
A number of manufacturers and industry alliances are
working to solve these problems, including the Software
Defined Video Over Ethernet Alliance (SDVOE), the
AVNU Alliance, and the Alliance for IP Media
Solutions (AIMS).
24 I ICT TODAY
DisplayPort
The DisplayPort video interface standard was originally
developed by the Video Electronics Standards Associ-
ation (VESA) as the next generation personal computer-
to-display interface replacing VGA and DVI. It competes
with HDMI and can be made compatible with HDMI via
cables and adapters.
The DisplayPort standard is evolving, and the most
recent adaptation is DisplayPort Alt Mode for USB
Type-C, enabling the full DP interface using a USB
Type-C connector and cable. This not only provides the
AV interface, but it also becomes the single connection
for data and power simultaneously on full-featured USB
Type-C cables.
Thunderbolt and USB
Thunderbolt is a hardware interface developed by Intel
Corporation in collaboration with Apple Inc. Starting
with Thunderbolt back in 2011 at 10 Gb/s, then prog-
ressing to Thunderbolt 2 in 2013 at 20 Gb/s, today the
latest version is Thunderbolt 3 at 40 Gb/s. It supports
USB 3.1 Gen 2 at 10 Gb/s and DisplayPort 1.4 capable
of operating two 4K 60Hz displays. Thunderbolt 3 uses
the USB Type-C connector.
One of the most recent announcements in the pro-
tocol arena is USB4. This protocol is based on Thunder-
bolt and promises to provide data transfer rates up to 40
Gb/s, display interfaces and power delivery simultane-
ously using USB Type-C cables and connectors. The
specification is expected to be released in 2020 and
promises to up the ante for device connectivity.
When designing an AV system with
the goal of reducing components
and system complexity, two options
are available: a centralized
or decentralized system.