24p
In video processing , 24p is a video format that is recorded or played back at 24 frames per second ( Hertz ) (or typically 23.976 frames per second if NTSC- based equipment is used). The "p" stands for the English term Progressive Scan .
24p is the standard format for movies . It was established as the international standard for film recording and projection as early as the 1920s and represented a compromise between low flicker and film material costs, and the introduction of sound film, which on the one hand required a constant frame rate so that the speed of the sound remained the same On the other hand, only a frame rate of at least 24 frames per second allowed an acceptable sound quality. In order to reduce flicker that is still visible, cinema projectors use a lens shutter that briefly covers each film image once or twice during its projection so that it is displayed twice (48 Hertz) or even three times (72 Hertz).
In contrast to this, television pictures are mostly transmitted using the interlaced method , which was justified by the technical possibilities when using tube televisions . Films recorded on DVD are also played back in this way, with a few exceptions on a few special playback devices that have not been able to establish themselves on the market.
With the introduction of Blu-ray Disc (and HD DVD ) as a high definition system, a possibility has been provided to store films in their natural rate of 24 frames per second. This is z. B. as 1080p / 24, i.e. H. a resolution of 1920 × 1080 pixels at 24 fps. Corresponding information can usually be found on the packaging of films encoded in this way.
Blu-ray players equipped with 24p playback capability can output these films directly to a playback device ( TV or video projector ) via an HDMI cable . Whether this happens depends on whether the player is able to receive a corresponding 1080p / 24 signal and sends corresponding, so-called EDID information for connection configuration to the player.
The further processing of the image signal coming in via the HDMI cable on the playback device can take place in different ways, with different effects on the displayed image, especially when moving in the film. Each method has advantages and disadvantages.
The most “cinematographic” approach consists in increasing the image frequency, as with cinema projectors, to 48 or 72 images per second by displaying each image two or three times in a row (so-called 2: 2 or 3: 3 pulldown).
Another approach is to not simply display the one or two subsequent images of each "original image" as repetitions, but rather to calculate an intermediate image based on the next image to be displayed in order to display movements more smoothly.
Finally, there are also playback devices that turn the 24p film into a 60 Hz sequence, which corresponds to the normal frame rate of flat screens (so-called 3: 2 pulldown, which is also used in television companies before films are broadcast).
In order to be able to easily integrate video recordings in the context of cinema film productions , video cameras have also been developed that can record in 24p (e.g. HDCAM ). This trend was later followed by camcorders and digital SLR cameras . The AVCHD format, which will become popular from around 2008, provides for such formats.
Various filmmakers advocate the replacement of 24p by the HFR format, which is controversial.
See also
Individual evidence
- ↑ Detlev Schnick: What you need to know about 24p, 3: 2 pulldown and jerking . hifi-regel.de. September 8, 2007. Retrieved October 14, 2011.