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Basic question about blu-ray, HD, 24p

flexy

flexy

Diamond Member
I have a HD plasma which has a so called "24p" mode which is supposed to play movies "as in the theater" with the right vertical frequency, 24hz (actually 23.9, but for the sake of simplicity lets just assume its 24hz)

*) the plasma is hooked up via DVI --> HDMI on my PC, and all the content is coming from the PC. I dont have a blu-ray player.

*) i cannot output respective set a screenmode with 24 vertical frequency with any media player. All what DVI/HDMI supports is various kinds of screen resolutions, but all are 60HZ. I also cannot set such a resolution in ATI control panel. (The card is an old X850). The manual of the TV also says that there is no such thing as a 24hz PC resolution.

*) does a blu-ray player actually output real 24 frames/seconds and is the only way to enjoy such "real 24p" movies via a blu-ray player? Why is this not possible via a PC connection DVi --> HDMI?

thx
 
The difference between 60p and 24p won't take away from the enjoyment of the movie (IMHO). Not sure about the PC resolution question.

My projector is a lowly 720p / 60Hz machine and I still very much enjoy Blu-ray on my 100" screen 🙂
 
There is no benefit to running a movie at that refresh rate, it's just a gimmick. I think the movies look better on my plasma than they do on the big screen to be honest.
 
I have some ideas as to why you're having issues setting 24hz output on your HTPC.

One: you may not have the right video card for it.

Two: your video or _monitor_ drivers might think you're hooked up to a monitor, not an HDTV, and are thus eliminating the 24hz option automatically.
 
its not marketing. how do you get 24 fps divided equally into 60 or 50hz?
you can't. which is why there are issues. now its also a problem solved by 120hz and such higher refresh as well as they divide evenly.
 
Malak said:
There is no benefit to running a movie at that refresh rate, it's just a gimmick. I think the movies look better on my plasma than they do on the big screen to be honest.
Click to expand...

Thats up to debate 😛

The 24p comes from movies that are shot on film and thus 24frames per second. Video isn't recorded at 24p so it's comes in at whatever rate it was recorded in ntsc or pal.

Purists want to see how the film was recorded and show in the cinema at home. For this you will need a device to output 24p and for your plasma/ lcd/ projector to be able to show a 24p image without sampling it but to show it natively.

If your not outputting 24p from your computer graphics card your not getting 24p. Some people notice it and others don't. Some people notice the stutter at the cinema when the image pans fast.

For me I want to see it how it was recorded. Not that I can tell a huge difference from non 24p stuff to 24p off blu ray 😛

Koing
 
I found out i can actually output a 24p resolution on my PC, but 1920/1080/24p. But my TV is a 720p TV, so it scales down and doesn't look as sharp as 1360/768. I can also check the "info" screen on the TV and the TV does indeed say "24hz".

Although i have NOT seen anything about this mysterious "24p" cinema mode...if at all it looks the same as running at the native 1360/768/60. The other problem is that my HTPC is a little old and running and playing 1920 already might be a little too much for the old X850XT in it.

The ultimate goal is indeed to sync the TV/refresh with the real 24hz frame rate to avoid that (minor) stuttering effect while panning/fast movement is happening...but as said i still need to see a difference. It just would make sense to me that the actual HDTV refresh is the same as that of the movie
 
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Koing said:
Thats up to debate 😛

The 24p comes from movies that are shot on film and thus 24frames per second. Video isn't recorded at 24p so it's comes in at whatever rate it was recorded in ntsc or pal.

Purists want to see how the film was recorded and show in the cinema at home. For this you will need a device to output 24p and for your plasma/ lcd/ projector to be able to show a 24p image without sampling it but to show it natively.

If your not outputting 24p from your computer graphics card your not getting 24p. Some people notice it and others don't. Some people notice the stutter at the cinema when the image pans fast.

For me I want to see it how it was recorded. Not that I can tell a huge difference from non 24p stuff to 24p off blu ray 😛

Koing
Click to expand...

The problem is with NTSC video as it runs at 30hz (29.97fps). For PAL, the movies are usually just sped up and nobody notices. With NTSC, you have to use 3:2 pulldown. Frames are duplicated in order to match the NTSC frame rate. It can create judder in movies with fast actions on during pans. Using 24p produces a smoother looking image.

Most people won't notice it but it's a must have for videophiles. Most TVs today AFAIK are starting to support 24p.
 
Yes they do, but i really think its a Gimmick or doesnt work, at least on my Samsung.

Setting it to 24hz i *assume* it actually refreshes at 72 or 96 otherwise i would see noticeable flicker. I see flicker eg. if i set to 60 and some other lower refresh rates, but i dont see flicker at "24hz" so i strongly assume it does 72 or 96.

I had some "test videos" in that 24hz mode to see whether that "telecine judder" goes away..but really cant see ANY difference, also with scrolling credits smoothness.

This on the background that i saw SOME people on forums posting that they had TVs with a 24p mode where they claimed to see noticeable smoother scrolling/panning...but maybe its just broken on the Samsung.
 
flexy said:
Yes they do, but i really think its a Gimmick or doesnt work, at least on my Samsung.

Setting it to 24hz i *assume* it actually refreshes at 72 or 96 otherwise i would see noticeable flicker. I see flicker eg. if i set to 60 and some other lower refresh rates, but i dont see flicker at "24hz" so i strongly assume it does 72 or 96.

I had some "test videos" in that 24hz mode to see whether that "telecine judder" goes away..but really cant see ANY difference, also with scrolling credits smoothness.

This on the background that i saw SOME people on forums posting that they had TVs with a 24p mode where they claimed to see noticeable smoother scrolling/panning...but maybe its just broken on the Samsung.
Click to expand...

Interesting article:

http://www.projectorcentral.com/judder_24p.htm
 
If you really want to see it like it is shown in the theater then you need 72hz for the output. 24hz would be awful to watch which is why film is shown at 72hz .

60hz displays are only around because of its roots in the past. Time base generators were extremely expensive when TV became mainstream in the 1940's -1950's, so they used the power line frequency to get the frame refresh rate. There was no reason to keep it when displays went to LCD other than needing to support previous formats.

The next generation of video does away with all this legacy hz nonsense and puts the playback device, blu-ray, satellite, or whatever in control of the displays frame buffer allowing 60 frames updated per second and the whole hz term goes away and becomes frames per second. Right now there is a lot of redundant hardware in getting a video from disc to screen.
 
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