I have a 1080p projector (Panasonic AE1000U) which apparently accepts 1080p24/50/60. I am considering buying a blu-ray player soon and noticed that although encoded 1080p24, all current players convert this to 60 fps. There may be future players that ouput 24 fps, although I am not sure if this will be via HDMI or other output.

My questions are:
1. Wouldn't a 24 fps movie be best shown at 48 (like in theater) or even 72 fps?
2. Does my projector have a "native" or default frame rate, such as 60 fps, or is there some way I can set it? It supposedly accepts 24/50/60p input.
3. A review of the projector says "Vertical scanning: 50-87 Hz" - does that mean it doesn't do 48 fps but may do 72 fps?
4. If the projector won't do it, would the DVDO VP-50 (doesn't appear so from web description)?

Thanks,
Ken

I'll answer #1:

On a digital projector that supports it you can view native 24fps with no issues. Film projectors run at 48 or 72hz to reduce flicker from the needed mechanical shutter. A CRT cannot run at 24fps due to the flying spot. However a digital projector does not require any refresh other than for the native motion rate of the image. So for 24 frame film, 24hz video is best. Barring that any multiple of 24 is also acceptable, 48, 72hz. It won't make any viewing difference from 24hz though. Simply flashing the same frame twice or three times it's capture rate does not reduce motion artifacts.

What does introduce mation artifcats is 3/2 pulldown used to make 24hz into 60hz so you want to avoid that if possible.

Thanks. I learned that my projector will take a 24 fps and project is 72 Hz, presumably to reduce flicker. Sony's Pearl apparently ups this to 96 Hz.

Re #2 and #3, the projector apparently does 72 on its own. I also didn't realize that the high end Sony and Pioneer blu-ray players already can output 24p.

It apparently does this well, though I still can't decide what output to use from my Pioneer DVD player (480i, 480p, 1080i?)

Also, I need to upgrade my old DVDO scaler, but I am not sure whether the VP-50 is worth the extra bucks.

Thanks. I learned that my projector will take a 24 fps and project is 72 Hz, presumably to reduce flicker. Sony's Pearl apparently ups this to 96 Hz.


This is a commen misconception amongst delaers and even some HT magazines. There is no flicker on a digital diaplay panel. That is DLP, LCD, or LCOS. The pixels on LCD and LCOS stay lit from frame to frame unless the video content wants them off. Likewise unlit pixels stay off until the scene content needs them on. The video signal is refreshing but the display panel does not unless the frame to frame content calls for pixel changes.

DLP is a bit different in that the mirrors are under constant motion to make gray. However once at the particular dither frequiency to make a certian shade of gray, they remain at that frequency until the scene content requires a different shade of gray.

In other words digital displays don't "blank out" between frames like a CRT or mechanical projector does. It's the blanking out that makes the flicker. So running a digital display a 48, 72, 96, or even 128hz will look no different than running at 24hz with a 24hz source.

Now Sony has introduced a broadcast quality LCD monitor at NAB this year that does actually blank the display 4 to 5 times per video frame. This however is to improve black level to the point of CRT quality. But this is a special application and due to the high speed blanking it still produces no visible flicker.

I have another question related to this 24hz (btw thanks for the explanation on digital displays): is it really 24 or 23.96 ? I understand the logic for 23.96 in films is to carry the sound track in cinemas. Now with HD-DVD/BluRays, are the video (output from the players and to be projected by a display) supposed to be produced as strictly 24hz or 23.96 Hz? In another words, what is the "real native" frame rate of these material stored in disc ? (I read in this forum the Sony BR player seems to suffer from some stuttering problem when it strictly outputs 24hz)

Thanks

Thanks, Glimmie, that makes sense. I won't worry about what multiple of 24 it is then...

Regarding the frame rate of 24 fps, I believe the usual for film is actual 24 fps. Some film productions use 23.976 fps in order to accomodate NTSC video. When color was added to NTSC in 1950, the frame rate slowed from 30 to 29.97. When you do 3:2 pulldown from film to NTSC, 4 frames of film become 10 fields of video (5 frames). 23.976x5/4=29.97.

Ken

I am considering buying a blu-ray player soon and noticed that although encoded 1080p24, all current players convert this to 60 fps.
Thanks,
Ken


Not so. The Samsung BD-P1200 in addition to the Sony BDP-S1 and the Pioneer support 1080p/24 Blu-ray output. :) The Samsung also makes use of the Reon-VX HQV to upscale DVD with very good results.

Dazzer

Question: Since all new Sony SXRD HDTV's and projectors are going to be 120 Hz, What happens to a 1080p24 output from a Blu Ray player since 120Hz isn't a multiple of 24? Does that just mean that the projector will run at 72 Hz for film? 120Hz for HDTV/video only? Not sure how pauses help also...

Now Sony has introduced a broadcast quality LCD monitor at NAB this year that does actually blank the display 4 to 5 times per video frame. This however is to improve black level to the point of CRT quality. But this is a special application and due to the high speed blanking it still produces no visible flicker.

But Sony claims the 120 Hz with the new SXRD panels is for improved sharpness during motion:

http://www.sony.co.jp/SonyInfo/News/Press/200704/07-033/index.html

The magic behind Sony's SXRD line is getting an update. Currently, the three sensors that drives the whole picture was developed way back in '05 - eons ago in gadget years - but Sony has the next gen ready to go. Nah, they didn't increase the resolution past 1920x1080 but the biggest improvement in our eyes is the adoption of 120Hz. This is the latest craze in HDTVs as it helps smooth out the picture, creating a very film like response. This new speed is twice as fast as the previous generation so users should see the difference on almost every moving image with less smearing. Sony has plans to stuff these new chips into their latest HDTVs and projectors so there is yet another reason to hold off purchasing an HDTV till you can see these. Sorry 'bout that....

5 X 24 = 120

I failed calculus 2 :D

In any case, please see the above links and explain how 120 Hz helps with motion... and can we also expect better black levels? My major dissapointment seems that the new Sony Panels emphasized 120 Hz, but did not bring with them the improvements of JVC with NATIVE 15,000:1 on/off contrast... As you can see from the link the panels are only 5:000:1 :(

I was really hoping Sony would match the same native panel contrast as JVC.... oh well.... Guess the Diamond will only be a minor improvement and nothing major to get excited about...

Some film productions use 23.976 fps in order to accomodate NTSC video.


this is exactly my question. Are we saying the players for HD-DVD/BluRay are supposed to do exactly 24hz and not 23.976 ? But then when sony players are really doing this (for avc encoded disks), why the JVC RS1 is having trouble syncing ? (so is it not a sony 24p problem ?)

So if 120 will be better than 24, then is using 48 going to be better than 24?
Confused here :(

If a PJ can display both 24 and 48 FPS, and your source can do both as well are you better off with the higher multiple of 24 or the lower?

120 is no "better" than 24. 120 is a "magic" number in that it is the lowest refresh rate that works equally well with "film" (24/48) and "video" (30/60) by eliminating the need for "pulldown" completely!

Also, to find the actual refresh frequency, divide the nominal rate by 1.001 - ie. 60/1.001=59.9400599

I still don't understand how 120 Hz helps with motion scenes better than 60 or 48 Hz... as per the links I provided above. I mean the Ruby was capable of 48 Hz anyway, so it is still 2:2... how does 5:5 help.... F'it its 2:30 a.m.

I still don't understand how 120 Hz helps with motion scenes better than 60 or 48 Hz... as per the links I provided above. I mean the Ruby was capable of 48 Hz anyway, so it is still 2:2... how does 5:5 help.... F'it its 2:30 a.m.

I'm not sure how 120 hz will "impove" SXRD which already uses a refersh of 96hz on 24/48 source on the Pearl. It may be of more benefit to LCD technology to eliminate motion artefacts that are more related to the tech as opposed to 3:2.

There's no reason (apart from cost/complexity) that a display cannot take 3:2 material and playback without 3:2 judder today. To playback 3:2 at 120 hz with a 60hz signal the display must still work back to the original 24 frames to avoid judder even with 120hz refresh i.e. 6:4

This is how Tosh describes the benefits of their 120hz LCD's -

"ClearFrame™ 120Hz Anti-Blur Technology

This advanced system virtually eliminates motion blur without decreasing image brightness, or adding flicker. Images are now crisp and clear regardless of image motion. ClearFrame™ doubles the displayed frame rate to 120 frames per second or 120 Hz. ClearFrame™ utilizes superior Motion Vector Frame Interpolation (MVFI) technology. Utilizing the power of the PixelPure™ processor, MVFI creates new frames, inserting them between the original frames."

Dazzer

O.K. so 120 Hz is best for both worlds Film & Video, but just to clarify a point for a newbie here.

1 When we watch a movie on DVD is this film or video?
2 When watching a live broadcast is this considered video?
3 When watching a movie that was shot film-less, is this considered a video?

I guess my confusion is how does one know sometimes if what you are watching is film or video, and if your PJ & DVD player is set for 24 and you want to pay your home made video on it one should readjust the PJ and DVD player to 60 for the best image?

Thanks

1 When we watch a movie on DVD is this film or video?Most often 24p film, but optically telecined to 1080/24p master tapes, then to consumer discs. (Visiting imdb.com, typing in the title, then clicking the 'technical' section often pins it down). Newer discs may be made directly from digital-intermediate (DI) production recordings, either telecined at 2k or 4k from film before downconversion to 1080p, or made without film with digital-cinema cameras.
2 When watching a live broadcast is this considered video? Yes. In the U.S. it would be 480i, 1080i, or 720p.
3 When watching a movie that was shot film-less, is this considered a video?Yes. See 1. Usually shot at 24 fps to emulate film, but some movies (http://archive.avsforum.com/avs-vb/showthread.php?postid=3085589#post3085589) are shot (rarely) at 1080/60i (30i) or 720p, the HD broadcast formats.

I guess my confusion is how does one know sometimes if what you are watching is film or video, and if your PJ & DVD player is set for 24 and you want to pay your home made video on it one should readjust the PJ and DVD player to 60 for the best image?
HD videos can be made at 24p or 1080/60i or 720p and other formats, but must be converted to 1080/60i with 2-3 pulldown (adding extra TV fields to match the 1080/60i broadcast rate), or 720p (U.S. HDTV). Displays or other hardware with pulldown reversal can extract and reconstruct the original 24p frames, but then often deliver them at 60 Hz, which can cause blurring judder. Display at 24p (some displays) or even multiples (48--120 Hz) is preferred. HD video shot at 24p is growing for TV production for cost reasons. -- John

I still don't understand how 120 Hz helps with motion scenes better than 60 or 48 Hz... as per the links I provided above. I mean the Ruby was capable of 48 Hz anyway, so it is still 2:2... how does 5:5 help.... F'it its 2:30 a.m.

Simple, it doesn't! With film you have 24 pictures per second. That's all you shot. That's all you got. Simply flashing them twice or even ten times each per 24hz time slice won't make any difference in motion artifcats. The wagon wheel is still going to turn backwards no matter how many FPS in multiples of 24 you play it back at.

Ditto that form video shot at 30 frames / 60 fields, or even 60 frames. The capture rate locks the motion artifacts into the material forever.

There is technology that can estimate intermediate frames but it's a guess at best. You simply can't accuratly produce information that was not there to begin with.

Thanks, Glimmie, that makes sense. I won't worry about what multiple of 24 it is then...

Regarding the frame rate of 24 fps, I believe the usual for film is actual 24 fps. Some film productions use 23.976 fps in order to accomodate NTSC video. When color was added to NTSC in 1950, the frame rate slowed from 30 to 29.97. When you do 3:2 pulldown from film to NTSC, 4 frames of film become 10 fields of video (5 frames). 23.976x5/4=29.97.

Ken

Film is always shot at 24fps. When undergoing the telecine process it is run at 23.98 so it's compatable with 59.94 SD video. Also ATSC is 59.94 for now. Audio captured on the set is can be a t 30, 29.97, 24, or 23.98 hz. The difference is corrected in telecine. The speed change is so small we don't worry about pitch.

Film scacnned for digital intermediate is at true 24 as it is going back to film plus the digital files must also be 24hz for DCI. If a home video version is genewrated from the DI data files, they are played out at 23.98 to video tape.