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24P and 30FPS what are the differences? what are the disadvantages?
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In video technology, 24p refers to a video format that operates at a true 24 frames per second (or typically, 23.976fps) framerate with progressive scanning (not interlaced). Originally, 24p was used in the non-linear editing of film-originated material. Today, 24p formats are being increasingly used for aesthetic reasons in image acquisition. Capturing video at 24p offers film-like motion, which is arguably more suitable for narrative projects and creates more film-like images. Some vendors market 24p products as a cheaper alternative to film acquisition.

Most film is projected in movie theaters at 24 frames per second - making it the highest resolution of any media format in common use today. The secret is 24p, that is, 24 frames per second, presented progressively.

Video always runs at around 30 (29.97) frames. Until now, film was converted to video by doubling some of the frames on a regular basis, so that it ended up at 30fps. And, even more awkwardly, to be converted to the PAL standard, film was simply sped up 5%, to the 25 frames-per-second that?s required for that format. Neither of these processes is perfect.

24P disadvantages:

  • Lower motion sharpness/smoothness  (if you move the camera too fast, the motion will look jumpy and choppy) It's prone to causing "artifacts", which look like a kind of "comb" effect, especially in slow motion or in still grabs from moving video. They are caused by the relative movement between two fields that make up a single frame. It's a fact of life, though, that 1080p, (1920 by 1080 progressive), which might appear to be the perfect format for high definition video, would generate too much data for current consumer technology, so we might have to wait a while for that.
  • Lower still-image sharpness 
  • Very hard to get it looking like video again if that's what you really wanted. 
  • Most edit systems are able to use 24P and 23.98 interchangeably, however you may have to pullup/pulldown your audio to match.
  • Most consumer-level video editors (particularly non-HD ones) are designed for 30 frames per second, and the addition of 24p is sometimes awkwardly implemented. Incorrect user settings can result in a 24p frame at the edge of an edit existing on only one NTSC field, thus cutting its resolution in half. If a non-linear editor is incapable of removing pulldown, the standard 2:3 pulldown pattern should be used when shooting
  • It?s hard to tell the difference between film?s 24 frames per second and video?s 29.97 frames, especially when the frames are doubled to prevent flickering.  And, with the official video standards not specifying whether home TVs will display progressive or interlaced signals, or 24 or 30 frames per second, the new TVs will be able to display any and all of these formats.


24P advantages:

  • Frame-grabbed stills from the video are free of interlace "comb" edges on moving images 
  • Some people seem to like the slightly "jerky" look of PS-mode video.
  • While editing video at 23.98 frames per second, you will also find that you can render faster as your hard drives have to send less frames per second to FCP, and the Mac's processors have less work to do.
  • 24 versus 30 frames represents 20% less frames that need to be processed, that need to sit on a disk, that need to be rotoscoped, manipulated and stored. That?s more efficient.
  • 24p cameras is that they offer nonlinear gamma settings as adjustable contrast profiles that can emulate the response of film to light.
  • If you remove the extra frames and edit in a 23.98p timeline, you can make a 24p DVD (See pages 45 and 90 of the DVD Studio Pro 3 manual for full details on making a 24p DVD) which will look better than the same video as a "normal" 29.97 DVD because less frames of video have to be fit on the disc and hence a higher bit rate can be used for the remaining frames.
  • More Accurate Inverse Telecine


30 FPS disadvantages:

  • None, other than the inferior quality  of stills captured from video of moving images (when computer-video/streaming videos are made, deinterlacing is easy, so it is not necessary to do this while shooting, damaging the original for TV-viewing)
  • Lower spatial resolution...a big disadvantage when compared to film
  • The problem with 30 is that it limits your distribution to 30P or 60i; it does not convert smoothly to PAL (50i) or film (24 fps.) So if your only intended release is 60i NTSC and 720/60P or 1080/60i HDTV (and the internet), then 30P is OK. But if there is a chance of a PAL release or European HDTV, then avoid 30P. 

30 FPS advantages:

  • Smooth motion-rendering
  • Best sharpness for both moving and still video images

Last update: 07:23 PM Thursday, April 5, 2007

 



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