Planet Earth I was the first major nature documentary to be filmed in high definition.
When it was originally aired in 2006 it had impressive ratings in both UK and US and it
won multiple awards, including several Emmys and a Peabody award.
More than ten years later, Planet Earth II is again pushing the boundaries by being one
of the first documentaries released in HDR on 4K Blu-Ray disks.
The sequel was again produced by the BBC Natural History Unit in Bristol.
However, this time it only has six episodes, compared to the eleven episodes of Planet
Earth I.
The episodes are stored on two 66 gigabyte 4K disks, which means each disk contains 3
episodes.
One of the main reasons for reducing the number of episodes was technical complexity.
Planet Earth II is using a lot of technology that was only widely introduced in the last
10 years, including drones for aerial shots, gimbals for steady shots, as well as low light,
infrared, and thermal cameras.
The main cameras used for the documentary were RED cameras using the Dragon sensor than
can shoot video in 6K at up to a hundred frames per second and 4K at up to a hundred and twenty
frames per second.
The high frame rates allow for more cinematic slowed down footage.
This sensor is excellent for creating HDR video since it has more than 16 stops of dynamic
range and it can capture video at 16 bit, which yields trillions of colors.
What all of this means is that the producers had a lot of latitude in post production to
adjust the colors and the exposure for the final 10 bit HDR video output that is stored
on the 4K disks.
Another feature that they liked on the RED cameras is the four second pre-record buffer,
which captures four seconds of footage before the cameraman presses the record button.
This feature ensured that they didn't miss any interesting animal behavior.
In addition to RED cameras, they also used the ARRI Amira, which can capture up to 10
bit 4K video.
But apart from these high end cinema cameras they also used a variety of equipment with
lower specs, including Sony A7S which is very good in low light, Panasonic GH4 that record
4K 10 bit externally, down to even GoPro HERO 3.
Finally, in terms of drones, they used some of the first versions of the Inspire 1 and
DJI Phantom drones.
Since they used a variety of cameras the quality of some of the shots is quite uneven.
The most obvious scenes with issues are the aerial shots that you can see right now.
If we zoom into some of these images you can tell they used pretty low resolution, most
likely 2.7K or 1080p.
The producers even admitted in interviews that about 20% of footage is not 4K.
Even some of the 4K footage that they shot is not up to spec, since 4K disks require
at least 10 bit video, but some of the cameras they used like the A7S can only output 8 bit.
One potential downside of 8 bit video is that banding can be visible when shooting the sky,
but since they used the Sony A7S at night, this is not very visible.
The decision to create an HDR master in addition to SDR came quite late in the post-production
process.
But what's really interesting is that the documentary was color graded in a type of
HDR called Hybrid-Log Gamma, which was proposed by the BBC in collaboration with Japan's NHK.
It was only at the end of the mastering process that HLG was automatically converted to Perceptual
Quantizer (PQ for short), which is the standard transfer function used for 4K HDR disks.
So keep in mind that what you get when you watch these 4K disks is not real HLG, since
that's not allowed yet on 4K disks.
But HLG may be widely adopted in the future for TV and Internet delivery.
While PQ can theoretically go up to 10,000 nits, HLG tops out at 5,000.
This is not a big difference since most HDR content today goes only about to 1,000 nits.
But what's most interesting about HLG is that it is backwards compatible with SDR content.
That is, you can play the same file on SDR and HDR screens, and it will lood pretty good
on both.
This is because HLG takes into account the maximum brightness of the display, as well
as the surrounding light in the room, and adjusts the brightness accordingly.
PQ on the other hand specifies absolute brightness in nits.
What this means in practice is that HLG content can be viewed in brighter environments than
PQ.
As you may have noticed from the graph on the screen, the brightness of Planet Earth
II mostly stays at less than 500 nits.
I found this very interesting because the movies I reviewed until now all went up to
1,000 nits in brightness.
To make this more obvious I added a horizontal white line at the 500 mark.
Here's how the same graph looks sped up over a bunch of the higher brightness clips I could
find.
I don't know if this is a side effect of the conversion from HLG to PQ, but the result
is that some shots where the sun is visible have lower brightness than what I am used
to with HDR.
Still, I think HDR is used quite well here, but it is more obvious in the scenes filmed
with the higher end cameras.
In closing, let me give you my wish list for future documentaries like Planet Earth.
I think they should start mastering the content at 60 frames per second, especially for the
hunting scenes.
I also think they should make the shots more visually consistent by using 4K 10 bit footage
throughout the episodes.
I hope to see these improvements either in future BBC documentaries, or in the Netflix
documentary "Our Planet", which is being filmed by the same team that worked on Planet Earth
I, and which will debut on Netflix in 2019.