Confused 24fps

[admin_exported]

What does this mean, 24fps ?

Also 50hertz and 100hertz are they all related in anyway ?

I was told that if watching fast action sports such as football or tennis a 100hertz TV would deal with the moving images better than 50hertz. Is this correct ?

So where does 24fps fit in to all this, if at all ?

Ta

 

[Andrew Everard]

Movies are shot at 24 frames per second, but until now have had to be speeded up a bit to suit the frame-rate of TVs, which in the PAL system is 25fps. This gives a slight upward pitch-shift in the soundtrack, and can cause slightly juddery movement, most obvious in slow panning shots, which can seem to jerk a little, thanks to the 'pulldown' system used to turn 24 frames every second into 25.

Now, with the arrival of Blu-ray, films can be delivered on disc at their original frame rate - cue lots of 'as the director intended' razzamatazz - but the TV through which you play such discs needs to be able to handle the 24fps frame rate.

50Hz is the European PAL TV standard - ie 25 frames a second, composed of 50 fields, or half frames, in the interlaced TV standard. Basically the TV writes a field made up of every odd line of picture info, followed by another made up of every even line, and leaves image retention in your brain to do the rest.

100Hz scans each line twice - that's in very simple terms! The jury's still out on the benefits of 100Hz over 50Hz for certain types of programming, even though this has been available for yonks. It varies according to the manifacturer's implementation - some users prefer 100Hz, while others are happier with 50Hz.

However, of course 24 doesn't go into either 50 or 100 exactly, so TVs able to show 24fps need to be able to write at a multiple of 24, usually meaning 48Hz or 96Hz.

 

[Anonymous]

I'm no expert, but heres my take, in english...it relates to movie playback from a high definition source (HD-DVD or BluRay).

Movies are originally shot in 24 frames per secnd and then typically sped up slightly for easier conversion for television display television (2.4% faster). Most HD source players allow the film to be sent to the television at exactly the correct speed that the director intended. The problem occurs that some TV's handle this 24fps feed badly.

Pioneer (and some others) set their screen refresh rate to a multiple of 24 (72 Hz) to allow a very good playback of this material. Others convert the 24fps to display on a 60Hz panel using something called 3:2 pull down by displaying some frames more than others, which can result in a jerky picture. Some TV manufacturers such as panasonic make a reasonably good stab at this.

The upshot is - if you want to see the film at exactly the speed the director intended, you need good handling of 24fps. If you couldn't care - there are wider cheaper choices available.

(Edit Just realised Andrew beat me to it.