- What
is HEVC (H.265)?
- How
does HEVC (H.265) work?
- The
impending format war: HEVC (H.265) vs. VP9 vs. AV1.
- Who
will win out in the end?
You may have heard a lot about HEVC (H.265) recently. Apple
integrated this next-generation codec into MacOS High Sierra, and professional
NLEs FCP X and Premiere Pro recently
were updated to support it as well. And other hardware and software vendors
keep announcing new support almost every month.
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This increasingly loud fanfare should come as no surprise
to anyone in the video industry. HEVC (H.265) promises to deliver high-quality 4k
video that is up to 75% smaller than before, and paves the way to an
even more ambitious 8k HDR future. This sort of performance is what we dream
about as video professionals, and HEVC (H.265) could radically simplify and improve the
jump to ultra-high definition content production.
If HEVC (H.265) takes off, it will shape the industry for years
to come. But there is growing competition
in the realm of futuristic codecs. Challengers like VP9 and AV1 have powerful
allies in the fight for our screens. So it’s time to sit down and take a good
look at HEVC (H.265) , and discover how it can benefit your video workflows.
What is HEVC(H.265)?
In short, HEVC (H.265) is the successor to the H.264 codec. If
you’ve read our definitive guide to codecs, you
should already be familiar with H.264. HEVC (H.265) was specifically created to provide
UHD HDR deliverables with wider color gamut’s, rather than just the HD SDR
Rec.709 deliverables of H.264.
The choice to use any particular codec is always partly
informed by what particular hardware is available. With CPUs in the last decade
or so becoming ever more powerful, cheaper, and more abundant, there has been
an industry-wide trend to trade storage space on hard drives for computation
via CPUs.
HEVC (H.265) is just the latest continuation of the trend in
trading storage for computation. In years past, digital intermediates like ProRes or DNxHR would
eventually be converted to H.264 for web or broadcast. HEVC (H.265) , on the other hand,
requires even less storage space than H.264, yet it requires even more CPU
power.
What this means is that the networks that we already use
to deliver our HD SDR Rec. 709 video will be able to deliver more data into our
video: higher dynamic range, wider color gamuts, and larger resolutions. The infrastructure won’t immediately require more
bandwidth. The more powerful CPUs that live in our new smart TVs, tablets, and
phones can decode more data out of the networks without requiring more
bandwidth, all else being equal.
Claims about being able to more efficiently compress data
into cutting-edge video codecs are exciting—but should you believe all the hype
about equivalent quality?
An initial
working group study that took place from 2013 to 2016 found
that HEVC (H.265) “clearly exhibited a substantial improvement in compression
performance, as compared to AVC [H.264].” The study tested two different kinds
of images: “natural” content and “synthetic” content. The “natural” content
consisted of real-world images captured by a camera, and the “synthetic”
content was from Sintel,
a test movie created with the 3D graphics application Blender. The
study found that HEVC (H.265) reduced the bit rate of natural content by 51% to 74%, and
synthetic content by 75%, with no loss of perceptible video quality.
How does HEVC (H.265) work?
What’s under the hood that magically allows for lower
data rates with equivalent visual quality? The answers are extremely technical,
and if you are so inclined, you can check out the slides from
Vivienne Sze of MIT and Madhukar Budagavi
from Samsung or the July 2012 issue of IEEE Consumer Electronics Magazine.
But for video professionals, here is a quick breakdown of HEVC (H.265) ’s compression
methods.
From Macroblocks to CTUs
Whereas H.264 would break an image down into squares of
pixels called “macroblocks,” HEVC (H.265) breaks down the images into “Coding Tree
Units” (CTUs) that can be up to 64×64 pixels. Each macroblock within H.264 can
have only interframe or intraframe prediction,
but not both.
Interframe
compression is when pixels are borrowed from adjacent
frames in a video, and intraframe
compression is when pixels are borrowed from within the
same video frame.
In HEVC (H.265) , CTUs actually use a combination of inter- and
intraframe compression. This means that there are more methods of preserving detail in complex
images.
You may have heard the term “macroblocking” to refer to
artefacts—those nasty compression artifacts when the 16×16 squares can’t
reproduce the fine details of a particular texture, like smooth gradients in
clear skies or blocky clouds with a wide variety of luminance. In contrast
to H.264’s macroblocks, HEVC (H.265) ’s CTUs don’t even need to be squares, so there’s
much more flexibility in how different parts of the image are compressed.
From 8 to 35 intra prediction modes
In H.264 intraframe compression, there are only eight
ways for each block to borrow nearby pixels. With additional computational
complexity, HEVC can use up to 35 different methods to borrow nearby pixels.
New kinds of filtering
HEVC (H.265) also uses new kinds of filtering to eliminate
would-be artefacts, such as sample
adaptive offset (SAO) and adaptive loop
filtering (ALF). These filtering methods provide a big
improvement over what is available for h.264.
HEVC (H.265) in post-production today?
All these technical capabilities are impressive,
and you might want to start using HEVC (H.265) for all your projects immediately.
Unfortunately, HEVC (H.265) doesn’t yet have universal support
for encoding and decoding in every post-production app, so you might need to
practice some patience before you can benefit from its impressive technical
capabilities. However, updates are steadily rolling out that enable HEVC (H.265) support.
- Apple
FCP X: Support for HEVC (H.265) first appeared in Final Cut Pro X 10.4, which was released back in
December 2017, but requires macOS High Sierra.
- Adobe
Premiere Pro: Premiere Pro
supports the import of HEVC (H.265) media with
resolutions up to 8192×4320, and can export to 720p, 1080p,
4K, and 8K, at 8-bit or 10-bit.
- Avid
Media Composer: As of this writing, HEVC (H.265) has not yet
been supported in Media Composer. If presented with it,
Avid MC users will need to convert to DNxHD.
- Blackmagic
Design DaVinci Resolve: As of April 2016, HEVC (H.265) can only
be decoded on macOS.
Who wants HEVC (H.265) ?
The Broadcast Television Industry
One of the big drivers of HEVC (H.265) will be the transition to
ATSC (Advanced Television System Committee) 3.0—the next collection of
technical standards for how television stations will broadcast out to viewers. Since the very outset of ATSC 3.0 planning, ATSC selected HEVC (H.265) as the core codec.
ATSC 3.0-compliant networks can broadcast 4K now. Later, if and when there’s a
demand for 8K, similar HEVC (H.265) pipelines will let broadcasters comfortably
upgrade without much difficulty.
There are several indications that HEVC (H.265) could take off in
a big way for broadcast. Over 2 billion devices already support it, so
producers and networks have a big incentive to make content for that user base.
Several high-profile deployments have showcased HEVC (H.265) ’s technical feasibility,
like the 2016 World
Series and the 2018
PyeongChang Olympic Winter Games.
Apple
To date, Apple has provided a few different tools for HEVC (H.265) encoding. Devices running iOS 11 can already handle 8-bit HEVC (H.265) content, so long as the device contains at least an A10 Fusion chip. For newer
macOS devices, Apple supports 8-bit HEVC (H.265) hardware encoding, and the High Sierra
update introduced 10-bit HEVC (H.265) software encoding.
Apple supports HEVC (H.265) in one form or another across their
entire product line, so it’s quite possible to deliver HEVC (H.265) content to hundreds
of millions of users almost anywhere.
Microsoft
It should be no surprise that Microsoft has mirrored
Apple in HEVC (H.265) adoption, though their support has been less consistent.
Originally, HEVC (H.265) was natively supported inside of Windows 10. But, Microsoft
dropped native HEVC (H.265) integration with the 2017 Fall
Creators Update, and now requires downloading and installing a
free Windows 10
extension.
In either case, Windows 10 should have no problem
handling HEVC (H.265) content, which pushes the codec’s reach to over 700 million more
mobile and desktop devices.
Living Room Companions
Of course, the living room is still a major media
consumption environment, and HEVC (H.265) has a growing presence there. The heavy
support of HEVC (H.265) by broadcasters means that TV manufacturers have a huge reason
to get behind the codec. Samsung, Sony, and LG have all started shipping
TVs that natively decode HEVC (H.265) , enabling much smoother live 4k content than
before. And video-on-demand apps are showing some HEVC (H.265) support too. Netflix has
been playing around with x265 (an open-source HEVC
encoder), Amazon Prime has adopted
the codec, and Hulu began UHD streaming with HEVC (H.265) as
well.
This broad support for HEVC (H.265) has already captured a huge
portion of the global media consumption market. However, rivals are fighting
back.
The Format Wars
A primer on HEVC (H.265) wouldn’t be complete without the
necessary context that HEVC (H.265) is but one challenger in the next-generation format
war. HEVC (H.265) has a good head-start over the competition but the jury is definitely
still out.
The Moving Picture
Experts Group (MPEG) is the body that oversaw the
development of HEVC (H.265) . They’re also the ones who oversaw development of MPEG-2,
MP3, and H.264 in years past. Because codec development is a big, complicated,
sprawling process, all the assorted businesses and organizations that help
develop such formats typically join patent pools to
recuperate the costs of development.
The patent pools are able to license the usage of the
codecs. Device manufacturers and software developers pay license fees to use
the codecs in their products. The cost of this licensing is then incorporated
into the price of the hardware or software.
This business model has worked for decades, but HEVC (H.265) hasn’t yet taken root like H.264 did because now HEVC (H.265) faces a worthy
competitor: VP9.
VP9
YouTube (owned by Google) was never fully satisfied with
the licensing agreement for H.264, and back in 2010 Google acquired a video
compression company that owned VP8, a comparable alternative to H.264. YouTube
then open-sourced
VP8 in the WebM container, unleashing into the world an
alternative to H.264 without any licensing fees.
By 2015, it was clear that YouTube didn’t want to license HEVC (H.265) , and didn’t bother with it. Instead, they adopted
VP9. VP9 is to VP8 as HEVC is to H.264.
AV1
In 2015, Amazon, Cisco, Google, Intel, Microsoft,
Mozilla, and Netflix created the
Alliance for Open Media (AOM). In 2016, AMD, ARM and
NVIDIA joined AOM and
AOM announced the new codec in development, now known as AV1. Bitmovin, the
co-creator of the MPEG-DASH video streaming standard, joined AOM in 2017. Hulu followed,
along with Facebook.
In July 2017, it was looking
like Apple was going to be the main backer of HEVC (H.265) , which could
have fueled a long and wasteful format war, but in a surprise twist, Apple quietly
joined AOM this past January as a founding member. The AOM
website was updated to include Apple on their list, without any kind of press
release, and Apple refused to respond to a request for comment. What this means
for the future of HEVC (H.265) is anyone’s guess, but since most major players are
members of AOM, it’s difficult to understand why they would want to pay the
licensing costs for HEVC (H.265).
In spite of AV1’s significant backing, HEVC (H.265) remains a
strong contender largely because of its significant head-start. HEVC (H.265) now has wide support in software and hardware, and
AV1 is starting from scratch. Because of the significant processing power
required to decode either of these two new codecs, it is impractical to expect
devices to play them back unless they have been specifically designed to
support hardware decoding. While most software can be updated reasonably
quickly to support new codecs, hardware is another story.
Leonardo Chiariglione, the founder and chairman of
MPEG, worries that
AOM won’t be able to fund research and development as well as MPEG would, and
the fast pace of innovation we’ve seen for 30 years from MPEG is about to slow
down.
Whither HEVC (H.265)?
Though many consumer devices, NLEs, and operating systems
support HEVC (H.265), the streaming industry is poised to adopt AV1. HEVC (H.265) may
be useful as a broadcast deliverable for ATSC 3.0 television networks, but
Google, Amazon, Apple, Hulu and Netflix all seem like they’re going to swing
toward mass adoption of AV1. On March 28 of this year, just in time for
the NAB 2018,
the AV1 1.0 spec was released.
It’s just a 1.0 spec, so while we wait for the industry to start shipping
products to encode and decode AV1, HEVC (H.265) could still take off. (YouTube
recently posted an AV1 beta launch playlist.
By downloading a beta of Chrome 70 and
tweaking a setting on YouTube, you can actually see YouTube’s implementation of
the AV1 codec in action.)
In fact, we may very well see a future where broadcast TV
defaults to HEVC (H.265) while streaming media defaults to AV1, and this isn’t just
because of the disagreement over licensing. Early results show that AV1 will be
100x slower at live media encoding than HEVC (H.265). This makes
AV1 technically unsuitable for wide swaths of broadcast 4k content, but isn’t
much of an issue for streaming companies who deal with relatively little live
content.
As you can see, a lot has been invested in the
development of these technologies, and the ability to save a significant amount
in licensing fees makes open source codecs like AV1 compelling. But, the speed
and adoption of HEVC (H.265) can’t be ignored. Your guess is as good as ours as to
which will ultimately win.
Have you already adopted HEVC (H.265)? Share your thoughts with
the community, and let us know how it has changed your workflow.
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Source: https://blog.frame.io/2018/09/24/hevc-format-wars/
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