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Several different frame rates, and how they are used in film and video.
Frame rate Also often described as frames per second (fps) fps ), is a term used to describe how many still frames we see in a second.MovieProducer, this will be one of the first settings you choose - 24, 25, 30. 24fps is generally considered the standard for "cinematic" frame rates. 30fps For broadcasting, the European broadcasting standard is 25fps.
In the one-second sequence below, there are several individual frames passing through each second. Specifically, there are twenty-four individual stills.
Below, we divide the footage into individual frames, with each frame representing 1/24 of a second.
Question for this section: Why 24? I find it very useful to know how the clock ticks rather than just what it is doing.ofWhy not 22 or 28.59? Why do we use these exact frame rates? Many filmmakers choose 24 fps because it is the standard fps for making your film feel "cinematic". However, cinema is just a relative term for what we think looks normal.
You may remember the many articles published in 2013 that talked about how The Hobbit movie looked like a cheap daytimeTV dramaThis is because it was shot at 48fps, which gives us a completely different aesthetic.
Why we24fpsThere are many reasons for shooting, and based on years of reading and research around the subject, there is no one specific reason. It is a combination of factors.
How humans perceive frames
We can perceive 10 to 12 passing frames as distinct individual images. As more images pass by each second, the gap between each image shortens and our brains recognize the images as motion. This was first documented by psychologist Max Wertheimer who coined the term phi.
From the early 1900s to the 1920s, there was no industry standard frame rate; there were no rules. It was simply in the best interest of the studio to keep the frame rate low — the higher the frame rate, the more film had to be used — and the more film had to be used, the more money it cost.
While higher frame rates would produce better persistence of vision, 16fps has become the unofficial standard for silent films. It’s enough to create the illusion of motion, and studio executives aren’t losing cash with every turn of the hand crank.
There are some variations on why 24fps was chosen in particular. In the video below (from Filmmaker IQ), John P. Hess explains that 24fps was chosen because the introduction of sound necessitated the start of a new modern frame rate standardization.
24fps was chosen because of math; it was an easily divisible number, and editors could calculate specific time cuts based on the number of frames. Twelve frames would be half a second; six frames would be a quarter of a second. While silent films were able to entertain the masses, filmmakers wanted to push their new medium further. They wanted audiences to hear spoken words, just as they would in theater. Additionally, the introduction of home radios offered new and exciting stories that movies and theaters could not. Pioneers in filmmaking had been experimenting with synchronized sound since the early 1900s. In the 1920s, they made their first breakthrough.
This was a failure for de Forest, but he later went on to invent Phonofilm, which introduced a method of recording a light track alongside the film. This technique made it physically impossible for the two to be out of sync, as they were in the same format.
You can watch the BritishencyclopediaA video from the film company, explaining exactly how this printed sound phenomenon is achieved.
Throughout the 1920s, various inventors and filmmakers continued to push both recording media. De Forest was advancing audio quality with his Phonofilm, while Western Electronic and Warner Brothers were pushing the boundaries of recorded disk formats with the Vitaphone, shown below.
However, the Vitaphone was about to blaze the trail for frame rate standardization. To overcome de Forest's synchronization issues with his disk format, both the Vitaphone's disk and the film projection were mechanically driven by synchronous motors powered by a common power source. This made it much harder for the sound to go out of sync.
The engineers behind the Vitaphone system chose to use a 16-inch disk format that played at 33 1/3 rpm. Spinning at 33 1/3 rpm would give the disk 11 minutes of play time, which is the same amount of time that 1,000 feet of film would play at 90 feet per minute: 24 frames per second.
Different film frame rates dictated different methods of capturing sound. This would change in 1927.
The following passage is from Moving Image Technology: From Zoetrope to Digital:
The standardization of identical filming and projection speeds is the first noticeable effect of the conversion to sound. While the reproduction of motion can, in some cases, vary over a fairly wide range without being perceived by the untrained eye, the reproduction of analog audio cannot, for the simple reason that changing the speed at which a recording is played back also changes its pitch.
In September 1927, SMPTE's Standards and Nomenclature Committee conducted a fact-finding exercise to determine what speeds to use for the emerging sound systems. The two that had entered commercial use (Vitaphone and Movietone) both used 24fps. The RCA variable-zone system, still in development, used 22fps, while de Forest Phonofilms (by then virtually out of production) ran at 20fps. Accepting this, the trends in exhibition practice over the previous decade and decisions made by the designers of the two most successful sound systems had effectively standardized on a default of 24fps.
So, we can say that 24fps is the default simply because the Vitaphone was released in 1927.The Jazz SingerIf not, 22fps will likely be the standard for shooting.
FPS vs. Shutter Speed
Shutter speed and frames per second are inevitably confused by those new to the medium. Although separate components, they both work together. While the frame rate determines the number of frames exposed per second, the shutter speed determines how long that frame is exposed.
How to Use FPS to Help Your Movies
How do you use frames per second to help you tell a story? The most common way to do this is, of course, slow motion. The old term for slow motion is overcranking, referring to the days of Lee de Forest, where camera operators would crank the film faster to increase the number of frames passing per second. This was pioneered by August Musger in the early 20th century.
The image above represents half a second of footage at 24fps. When shooting at double the frame rate (48fps), you are capturing a full 24 frames in half a second. These extra frames are then interpreted as your standard frame rate to produce slow motion.
What is downshifting?
As you may have guessed, Undercranking is the opposite of slow motion. It is a form of fast motion. However, the act of lowering the number of frames per second essentially becomes what we now know as time-lapse photography. Taking still images and conforming them to a motion sequence is more cost-effective than shooting with film or a movie camera.
For dramatic or comedic effectaccelerateGone are the days of slowing down the character. Unlike the days when movies were shot at a lower than normal frame rate and then sped up, many filmmakers can now shoot at 24 fps and increase the speed of the footage in post.
