144 STREAMING MEDIA INDUSTRY SOURCEBOOK 2018
humans don’t perceive a delay that small,” the company wrote in a 2013 blog post.
“But in an application where a machine interacts
with video—as is common in many automotive, industrial, and medical systems—then latency requirements can be much lower: 30ms, 10ms, or even under
a millisecond, depending on the requirements of the
system,” the company added.
While it’s unlikely that streaming video will ever
require the nanosecond accuracy of HDMI distribution, there’s still a significant amount of content
to process. A typical 1080p video signal generates
approximately 62 million pixels per second for 30
fps content, and double that for HFR content at 60
fps. A field-programmable gate array (FPGA) has
enough processing power to deal with compression
in a highly deterministic manner, since it doesn’t
face issues that a GPP is prone to, such as task
This 100–300 ms lower latency is in marked contrast to a 2-or-more second delay for HLS near-real-time streams.
While there isn’t room in this Buyers’ Guide to go
into additional detail around use cases for varying
latencies, a white paper I assisted with in 2017 (go2sm
.com/siglinlatency) covers several of the key trade-off elements, comparing low-latency live streaming
with near-real-time streaming in terms of reach
When Hardware Is Key
To wrap up this Buyers Guide, though, we’ll focus
on three key areas where hardware encoder appliances excel:
1. Ultra-High Resolutions: Software-based encoding
on the latest GPPs and CPUs, as well as on mid- to
high-end graphics processing units (GPUs), does a
rather decent job of encoding full-motion 720p HD
video content. For 1080p content, especially at high
frame rates or high dynamic ranges (HFR and HDR,
respectively) the need still exists for high-density
encoding via hardware.
Nowhere is the need for hardware acceleration
and dedicated appliances more apparent than in
the realm of 4K or Ultra HD video content. For this
resolution, which is four times that of 1080p (which
itself is four times that of 720p), the current need for
hardware-assisted encoding is indisputable, especially if frame rates rise to 50 or 60 fps for sports and
high-motion action content.
The advent of 8K panels, as demonstrated at the
Consumer Electronics Show in Las Vegas in January 2018, also requires hardware in both the encoding and decoding of content, with adoption of 8K not
slated until after 2020.
2. Baseband Video Inputs, Both Analog and Digital:
In the post-analog era, where many consumer devices have met the “analog sunset” requirements by
removing either analog output connectors or the
software functionality of these connectors, it may
seem ludicrous to suggest that baseband analog
inputs are still relevant for encoding appliances
in 2018. Yet the number of analog cameras in the
field continues to not just persist, but also, in some
emerging markets, to be on the rise. The extra-long-tail nature of analog video equipment necessitates
at least the option of analog inputs on today’s encoding appliances.
3. Real-Time Operating Systems: Real-time streaming needs a real-time operating system (RTOS).
There, I’ve said it. While we will continue to debate,
probably for the next 20 years, whether embedded
operating systems based on mainstream OS choices
(e.g., Linux variants, stripped-down Microsoft Windows OS versions, or even mobile device OSes such
as Apple’s iOS and Google’s Android OS) are proper
platforms on which to base a highly time-sensitive
appliance such as a low-latency video encoder, one
fact remains: single-purpose operating systems for
single-purpose encoding devices eliminate many of
the underlying effects that plague GPPs and mainstream OSes.
On the flip side, an encoding appliance with an
RTOS is often limited in terms of its upgrade path,
requiring the replacement of a customized, appli-cation-specific integrated circuit (ASIC) or the re-programming of an advance RISC machine (ARM),
digital signal processor (DSP), or even FPGA firmware to be able to update standards-based compliance as the MPEG, or the ITU, or other standards
bodies publish specification updates.
Hardware Still Matters
The constant need for hardware encoding for newer formats, balanced against software-only solutions
that take advantage of the latest CPUs and GPUs,
may just be the streaming industry’s analog to a CPU
manufacturer’s tick-tock approach to features and
processor size. Until resolutions, frame rates, and
color bit depths level off and solidify into consistent
standards, there will always be a need for hardware
encoding appliances, especially when it comes to
lower-latency encoding and delivery.
Tim Siglin is a streaming industry veteran and longtime contributing
editor to Streaming Media magazine.
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