In the AVworld, many terms that are difficult to understand, such as high dynamic range and Ultra HD . A term that we are also seeing more and more, but which is still relatively unknown, is High Frame Rate (HFR). In this article we explain what High Frame Rate (HFR) is exactly and what it can do for you.
The frames per second
If you know a little about how video is put together then you know that a film / video consists of a large number of photos (frames) that are played in quick succession. The brain sees playing these frames in rapid succession as one smooth movement; a movie. A cinema film is recorded at 24 frames per second. This standard was established many years ago for being able to display a film smoothly, without flickering images. Filmmakers used to have to pay a lot of money for a roll of film and so the minimum required number of frames was introduced as the standard.
Nearly all films are now digitally recorded, so cost savings is no longer an argument. Yet everything is still recorded at 24 frames per second, with the reason that this number of frames provides a certain ‘look’. It gives the ‘movie look’ to movies. In our reviews we often talk about the motion options of a TV, which allow images to look smoother. If you open this option full, so that extra frames are ‘made up’, then a film often gets a home video look, and that is something that we do not want. Even now, 24 frames per second is used.
High Frame Rate (HFR)
Still, a number of filmmakers, including Peter Jackson from The Hobbit, have tried to shoot at higher frame rates. However, this did not catch on, especially because viewers described the result as ‘cheap video’ and some viewers even indicated that the combination of HFR and 3D made them nauseous. Every now and then another filmmaker tries it, but it is still not a success.
Still, HFR does have a future, because by stopping more frames in a second, you simply get smoother-looking images. And if there is one problem with TVs that many people complain about, it is that the movements are not displayed smoothly. HFR therefore seems to have a particular chance in the field of TV programs and sports.
In the Netherlands, many programs are recorded at 25 frames per second, and are broadcast at a frequency of 50Hz as ‘half’ frames. The TV then turns it into one frame by means of deinterlacing. Cameras, however, have been able to record 50 frames per second for some time, and this is increasingly being used. As mentioned above, TVs can already display more than 25 frames per second and to use this the motion options are turned on. With series and films, however, this provides the well-known home video effect. What TV manufacturers do has to do with software and an algorithm. Most of the frames that you see when you turn on the motion settings are ‘calculated’ and therefore not original. In addition to having a home video look as a result, this can cause errors in the image. HFR is therefore not the same as the motion techniques used by manufacturers of TVs. HFR is a higher frame rate in the recording, after which the recording is also broadcast with a higher frame rate.
What will the future bring?
The ITU (International Telecommunication Union) is an organization that sets standards for broadcasters on paper. Which standards must a broadcast meet? In the latest standard, called Rec. 2100 outlines what the future of broadcasting should look like. For example, we see here the Ultra HD resolution, high dynamic range and a larger color range. There is also talk of a maximum frame rate of 100 frames per second (European). In addition, TV manufacturers will immediately start working with this development and we can expect TVs in the short term that can display a signal of 100 frames per second.
The fact that we are going to HFR has a number of important advantages. These advantages do not lie with film – after all, we want to keep that film look – but with sports and TV broadcasts. Sports in particular will look a lot better with High Frame Rate. This is because in sports there are many fast movements that must be displayed smoothly. With only 25 frames per second, this can often cause stuttering images or smeared details. As soon as we go to 100 frames per second, this problem largely disappears and a football match not only appears more realistic, but the movements you see are smoother and more natural.
At the moment there is plenty of testing with higher frame rates, by both broadcasters (especially the BBC) and TV manufacturers. Demonstrations and prototypes are already shown at trade fairs, so it will not be long before we hear important announcements on the hardware side and on the software side. However, the question now is which developments broadcasters will get to work on first. The choice is wide, including high dynamic range, Ultra HD, a larger color range, new audio standards, etc.
