High Frame Rate, or HFR, is a TV and movie practice that relates to the number of frames used per second. It's a well documented practice, but rarely do directors go above the standard 24 frames per second for their movies. That's started to change though, as the technology available becomes more capable, for filming, broadcasting and displaying higher frame rates.

So what exactly is HFR, what content uses it and how can you watch it? Allow us to explain.

What is HFR?

HFR stands for High Frame Rate. It relates to any content that is filmed at a higher frame rate than the standard 24 frames per second (fps) used for the majority of films. Why 24fps? It was chosen as the standard because it is the minimum frame rate that can produce decent sound quality. It was also chosen because it didn't use up too much film, so costs could be kept down.

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Fps refers to the number of discrete images displayed by a device every second. The human brain can interpret between 1 and 5 individual images as separate images, anymore and they're perceived as motion. As the number of frames per second increases, the motion becomes smoother and motion blur is eradicated. This is because the brain can't really distinguish between individual images around and above the 50fps mark.

If you're not sure exactly what effect changing the frame rate has on a picture, this website provides a great example. 

What content uses HFR?

Peter Jackson's The Hobbit trilogy, which saw the first film release in 2012, were the first wide-release films to use HFR, being filmed and shown in select cinemas at 48fps. Because not all cinemas could project the films at 48fps, all three were converted to 24fps.

Film director Ang Lee has experimented with HFR too, filming some scenes in his 2016 film Billy Lynn's Long Halftime Walk at 120fps.

The web series Video Game High School, produced by RocketJump, mixes reality with in-game sequences and has amassed a cult following, uses 24fps for read world scenes, but jumps to 48fps for scenes that are shot "in-game". The series is available on YouTube and Netflix, but can only be viewed in the mixed frame rate via RocketJump's website.

James Cameron has also stated that he intends to use HFR for the Avatar film sequels.

A lot of TV shows are broadcast at frame rates higher than 50fps, especially since the introduced of high definition TV. Sporting events in particular benefit massively from higher frame rates, as it vastly reduces motion blur, so the football for example is easier to see.

If you have the latest GoPro Hero 6 Black action camera, you can record 4K video at 60fps or 1080p HD video at a staggering 240fps. While 4K60 will offer super-smooth playback, you won't be able to watch HD footage at 240fps, instead, it can recorded and then edited to give super slow-motion, ideal for showing off any tricks you perform.

How can I watch HFR?

HFR films require specific equipment to be able to play them back. Not many movie theatres have the technology, but they're slowly being upgraded as the technology becomes more popular. It's taking some time because directors seem to be hesitant to adopt it in their films. Peter Jackson is the only director so far to truly embrace HFR and James Cameron is the only other one who seems willing to give it a go.

You're more likely going to get HFR content on your TV at home, because a lot of modern HDTVs have 100Hz or 200Hz refresh rates, or higher. The signal it receives will always be 24fps, but the TV will intelligently work out interpolating frames, the frames in between, and fill them in to reduce motion blur and give a smooth picture.

It's similar to when your TV upscales standard definition content to high definition or even 4K Ultra HD, it has to read the data it has to hand and then work out how best to fill in the gaps.

However, this form of HFR isn't the same as when a film is shot in HFR and then played back in at the same rate, as the TV can occasionally incur a few errors, especially during fast movement.

LG however has already demonstrated 'proper' HFR, that is, TVs rendering 100 to 120fps back at IFA 2016. The two prototype OLED models used for the demo were showing HLG (Hybrid Log Gamma) HDR (High Dynamic Range) video clips from the BBC and the European Broadcasting Union (EBU). 

We're still likely a little way off getting TVs that support 100fps+ rendering into our living rooms, but now that manufacturers have begun delving deeper into the technology, we'd expect to hear more news about their plans soon. Our eyes are firmly set on CES, that's for sure. 

Advantages of HFR

Higher Frame Rate content will give a much smoother image compared to 24fps content. It's capable of showing up greater detail within scenes. It's especially useful for gameplay as it can significantly reduce lag. You may not necessarily need this in your bedroom at home, but for competitive gamers in eSports tournaments, it could be the difference between winning and losing.

Disadvantages of HFR

Just as some may view a smoother image as an advantage of HFR, others will see it as a disadvantage. It comes down to personal preference, but many see the smooth motion of HFR films as too "soap opera-like", and they lose a sense of theatricality.

If a film is shot in HFR, then the set, prop and costume designers all have to take extra care when creating items for the film. HFR films show up a lot more detail than non-HFR movies, so any discrepancies, such as being able to see modern day technology or items in a period film, will be seen by the audience. 

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