What Is The Frame Rate?
It can be a little daunting to start with a video, particularly when you hear so many technical sound terms such as the frame rate or fps.
Even though you've heard about frame rate, you can't know what your videos are best for. After all, when selecting a frame rate, there are many variables to be taken into account.
We will explain the definition of frame rate has been broken down and why it is important in a simple guide. Also we will show a very important technical parameter which is the frame rate (Framerate), or the number of frames per second.
Definition
Frame rate is a unit of how many frames will be broadcast (or recorded) in one second. The term fps (frames per second) is frequently used.
A video is a series of still images. Depending on the speed of the succession of these images, we have get a more or less fluid or jerky video. For information, our brain reads a series of still images as a continuous action thanks to two phenomena: ‘retinal persistence’ and the ‘phi effect’.
When choosing the frame rate, there are generally two main motivations: workflow and/or a special effect.
The Workflow
Workflow is a very important concept in the film production chain.
In summary, the workflow is the fact of optimizing the various technical parameters to ensure continuity and consistency throughout the film production chain. In general, we start from the target of distribution of the film to define the parameters that we will apply from the shoot. However, other technical elements, such as special effects, may require some adaptation.
Coming back to Framerate (frame rate), there are "standards" to which it is always good to refer to respect a good workflow.
At the very beginning of Cinema, following various experiments, we quickly realize that a minimum of 10 frames per second was necessary to have an illusion of movement. To keep things fluid, we are running at approximately 16 fps (between 14 and 20 depending on the operator and the projectionist).
With the advent of synchronous sound, this frame rate was not sufficient to obtain all sound frequencies. It was therefore necessary to increase the number of images per second without exaggerating, because the film is expensive. However, 24fps seemed a good quality/price compromise.
Then we invented television. In summary, to ensure good consistency, the number of images per second has been synchronized with the frequency of the electrical network; .and being at 50Hz in Europe, television is at 25fps and in the United States (or Japan), as they are at 60Hz, they have adopted 30fps.
Is Higher Fps A Better Quality?
A higher fps does not mean a better video quality. You don't adjust the file output size (i.e., 1080p/4k) when you change the frame rate. You can have the same 1080p HD quality performance if you are shooting 24fps or 120fps. But a higher frame rate can make the shoot easier if you take handheld. But a better frame rate can benefit you. All camera shakes are less evident, given that it is slowed down.
Can You See Over 60fps?
The answer is Yes! In less than one millisecond, the human eye can respond to visual signals or convert them into a frame rate of 1,000 fps. However, with the displays we use to view video, most LCD displays are refreshed at only 60 Hz (hz). Eventually, it would only deliver 60fps for our eyes even though we looked at anything at 1,000fps.
What Frame Rates Are High Speed Considered?
Any frame rate at or above 60fps is a high frame rate. For instance, 60fps, 120fps and 240fps are considered high-speed and mostly used for slow motion video applications. Certain cameras can even go up to a thousand frames per second. In videos of a bullet in slo-mo, or a balloon, you have probably seen some examples of this image rate.
Summary Of Standards:
Cinema: 24fps
European TV: 25fps
Television USA & Japan: 30fps
And there, I see you coming. You can tell me that sometimes other choices are possible, more barbaric: 23.976 fps, 24.975 fps, or 29.97 fps. What is that?
These are standards that appeared when cathode-ray televisions began broadcasting in color. They can be explained by complicated technical calculations, but remember that this was the solution to avoid interference between black and white signals and color analog signals. And at the risk of being mistaken: it is hardly used anymore!
Conclusion
Today you have three standards to know: 24fps, 25fps, and 30fps. Almost all broadcasting media (cinema projector/television/computer) are capable of reading these three standards. Our advice would therefore be: stick to the conventions if there is no artistic intention behind them.
But, you can also have fun with choosing the frame rate to give a particular effect. The Hobbits trilogy, for example, was shot at 48fps, which results in much smoother footage. This is reminiscent of video games which are typically 60fps. Shortly, feel free to do some tests!
The Effects
Exceptionally, you can change the frame rate when shooting to create "effects". Of course, we want to talk about slow motion and/or speed up! However, even if you shoot at a different frame rate, the goal is to keep the broadcast frame rate set by the workflow, which is what will create the expected effect.
The Fast Track
To do a time-lapse (we sometimes talk about TimeLapse), it is necessary to reduce the number of frames per second. For example, if we record one frame per second, and broadcast at 25fps when we watch the movie, we will see 25 seconds broadcast in 1. This is time-lapse x5.
We have the opportunity to go into more detail on this process, but we will leave it to you to imagine the importance of doing the calculations. For example, we know we want a 5-second shot where we see the sun go down. If you want to shoot the sunset for two hours, you have to determine the frame rate.
Slow-motion
On the other hand, if you want to get a nice slow motion, it is important this time to increase the number of frames per second. If we shoot 100fps and play them at 25fps, we get 4x slow motion. Likewise, you will have to think carefully beforehand about the type of slow-motion you want to achieve and the phenomenon you want to film.
We hope the notion of frame rate is become clearer to you also, we wanted to point out that the frame rate is necessarily linked to the exposure time and that it is always to be taken into consideration, but that is another story!