For higher education, the pressure to deliver at anything higher than 720p doesn’t come from students, who are far more likely to
stream their curricular video to personal mobile devices than to a communal UHD TV set.
If we are to leap to a significantly higher recording resolution, our justification cannot depend
on preventing continuity errors at the same level as for entertainment video, so let’s explore
some justifications for shooting in 4K while delivering at lower, mobile-friendly resolutions.
Suppose we’re shooting a demonstration
where the subject is unpredictable: If there’s
a shot where we can’t know precisely where
to aim the camera, then having four times the
freedom of framing is useful. We recently recorded a gymnast performing on a horizontal
bar to demonstrate a concept for a mechanical engineering course. Out of respect for the
student-athlete’s time, we wanted to set up the
shots wide enough to accommodate any reasonable contingencies and let her get back to
her own business as soon as possible. In post,
we’d punch in to the framing we would have
picked if we’d had multiple takes. A 4K frame
would have offered a luxurious comfort zone.
Similarly, while shooting laboratory footage,
it wouldn’t be extraordinary for something serendipitous to happen that the presenter would
explain off the cuff. At 4K, the camera operator
need not even attempt to zoom in on what he
guesses is relevant. Shooting in 4K, we can “
enhance” in post once we’ve discussed with the
expert what to show the students, so we don’t
have to risk an otherwise solid shot.
Or maybe it’s not the subject’s position that’s
unpredictable, but the camera’s. We occasionally mount a camera to a drone, where sections
of the frame will be sacrificially shot and discarded for image stabilization purposes.
Even for talking-head shots, we can shoot
wide at 4K and punch in to the desired framing
in post, simulating a multi-camera shoot by cutting between two zoom levels from the same 4K
footage to hide edits.
I find these arguments to be compelling, but
my team members have yet to make that leap
to 4K. Now why is that?
First, the urgency simply isn’t there. The dif-
ference between HD and 4K isn’t as dramatic
as it is between SD and HD. We aren’t changing
the shape of the frame, we’re simply record-
ing four dots instead of one. HD footage won’t
look intolerably anachronistic; even when we
switch to 4K, we’ll occasionally make a mis-
take when setting focus and work from slightly
blurry footage. My intuition is that, at 4K, we’re
shooting deeper, not bigger. Most scenarios in
educational media production don’t require
that depth of resolution.
Second, I’m not convinced the 4K shooting technology is mature enough to invest in,
and camera manufacturers appear similarly
circumspect. Specifically, there are two video
codecs efficient enough to store 4K resolution
video at bitrates that suit our existing portable
media and fileservers: HEVC and AV1. HEVC
(or H.265) is the successor to the HD-standard
codec H.264, and boasts the ability to halve the
file size without compromising picture quality.
It is, however, encumbered with a complicated
and evolving licensing scheme. AV1 is the successor to the royalty-free VP9 codec (among
other projects by Alliance for Open Media participants), and is scheduled to be released by
the time this issue is published.
Camera manufacturers are conspicuously
not recording video with these video codecs.
The only cameras I know of that shoot 4K video
using the H.265 codec are sold by Samsung—
or at least, they were. CES 2017 came and went
without a significant announcement about
HEVC adoption in cameras, aside from the notably restrained (albeit impressive) features of
the Panasonic GH5’s debut firmware.
I’m waiting on the answers the camera manufacturers get to two critical questions: Will
AOMedia’s AV1 codec be good enough to adopt
over HEVC? If not, will it be good enough to push
HEVC’s licensing costs down enough to cover
the difference in quality? My bet is that we can
afford to wait another year to find out.
4K: What’s the Hurry?
Liam Moran ( firstname.lastname@example.org) produces curricular digital
media and manages the servers to store, process, and deliver
it at the Center for Innovation in Teaching and Learning at the
University of Illinois–Urbana-Champaign.
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