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24p Digital Video

The fact that the frequency of AC power – 50Hz in Europe and 60Hz in the USA – was used to lock video frames in each of the PAL and NTSC video standards, was a principal factor in the frame rates used by each of formats – 25 fps and 30 fps (more correctly 29.97 fps) respectively. The different frame rates used by TV video formats and the motion picture industry, where the standard is 24 fps, has long been handicap to broadcasters and film makers wishing to reach as wide an overseas market as possible.

Until now, film has been converted to video by doubling some of the frames on a regular basis, so that it ended up at 30 fps. And, even less satisfactory, conversion to the PAL standard has required that a film be sped up by 4%, to the required 25 fps. Neither process is perfect, and motion artefacts simply can’t be avoided. However, Hitherto, convergence has been but a distant hope, with neither the TV or motion picture industries showing any willingness to change.

Wisely, both the ATSC and DVB digital television standards include 24 fps formats, and it is the 24p format that is enabling the convergence between TV and film to become reality and which has the potential to become a universal mastering format. 24p has a resolution of 1920×1080, like the 1080i format, but runs at 24 fps like film. Its key advantage is that all world TV standards – PAL, NTSC and HDTV – can be down-converted from a single digital master without the loss in quality associated with PAL/NTSC transfers.

Some believe the 24p format could replace film for high-quality drama, commercials and even movies, a view that gained a lot of credence when George Lucas decided to shoot – using the new 24P HD cameras from Sony – and even project his recent Star Wars movies in video. The advantages are savings on undeveloped film and lab processing costs, speeding up production and easing getting special effects material into computers. It is possible that the format could also be used for theatrical distribution via satellite – a move that would eradicate duplication expenses as well as improving security.

 

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