Originally Posted by budeone
I would be telling a lie if I said I understand fully.
I am going to set up Anthem at 60 out with 4:4:4 and change my Sony Blu ray to 24. It is set at 60 now. I always thought the more frames a sec the better the pic. The picture is so good now I just cant imagine changing the player to 24 can actually make it better.
I bet you could make money setting these up for people.
Thanks once again.
When you have some time, read through the various links collected in the first post in this thread. There's some helpful material on technology and terminology for example that may make some of this a bit less of a mystery for you.
The reason why more frames per second is sometimes not better is when the original form of the content was recorded at a rate which is not an even multiple of what you are trying to use for display.
For example, if you record a movie at 2 frames per second and try to display it at 3 frames per second, you can't just flip the frames faster because that will speed up the movie and it will look unnatural. But what's to do? You don't HAVE a third frame to use each second.
Well you could display the first frame (in each second) for 1/3 second and the second frame for 1/3 second and MAKE UP a third frame for the remaining 1/3 second. The movie would play at a "natural" speed then. But how to make that third frame?
The easy thing to do would be to display the first frame TWICE (1/3 second each) and the second frame once -- or the other way around. Except now the movie kind of stutters along since some frames appear on screen for a longer period of time than others.
Or you could try to invent a third frame which is kinda sorta halfway in between what's in the first and second frame. And the problem here is that there's not really any good way to do that which the eye won't pick up as strangeness in the imaging.
Well this is just the problem with viewing movies on TV.
Film cameras used to make movies advance the film at 24 frames per second. TVs, on the other hand, put the next image frame up on the screen 60 times per second. And 60 is not an even multiple of 24. If you could just speed up the film camera to 30 frames per second it would work (just display each frame twice to make 60fps). But you can't.
So to make it work, movies are adjusted for TV broadcast. Each frame is divided up into 2 "interlaced half frames" called "fields. One field of each frame has all the even lines of the image and the other all the odd lines.
Then some additional frames are INVENTED by taking a field from one frame and merging it with the alternate field from an adjacent frame. If you take the 2,2,2,2 sequence of movie fields and duplicate some, but not all, fields to produce a 2,3,3,2 sequence the result is that you end up with the right number of fields to make all the frames you need -- some real, original frames and some invented. The result is 30 fps which can be displayed on a traditional TV just fine. This is the cornerstone of the "telecine" process.
However, some fields are now on screen for a longer time than adjacent fields and the brain can see this. Fortunately, the brain chooses NOT to see this most of the time. It tricks itself into thinking there is actually no such "cadence judder" in what it is seeing. Which is why watching movies on TV channels works so well.
But the judder is still there and there are certain TYPES of scenes where the brain actually sees it. For most people, their first realization that cadence judder exists is when they are watching the credits scroll smoothly up the screen at the end of a movie. Except it isn't QUITE smooth. It's a tiny bit jerky. That's cadence judder.
Well if you had a TV which was capable of switching it's image "refresh rate" to a multiple of 24 instead of 30, and if you had a source which would send along /24Hz movie imaging instead of doing telecine to raise it to /30Hz, then you could see the movie WITHOUT cadence judder.
And there are some TVs that will do that today.
Pretty soon now you will also start seeing TVs that are designed to use a /120Hz refresh rate. This is cool because 120 is and even multiple of BOTH 30 and 24. Which means you could switch between /24Hz content from movie film and /30Hz content from live TV cameras without having to change refresh rates in the TV.