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Are smooth pans really possible?

928 Views 13 Replies 10 Participants Last post by glavs, Sep 10, 2003

glavs

Discussion Starter · Sep 9, 2003

If anyone has the Mummy DVD, please try this out - play the opening scene where the camera pans down from the sun, to the pyramid, down to ground level, and then horizontally, from left to right, ending on an image of a chariot riding into the city.

Does anyone have a system that can play this scene completely smoothly? I've tried a myriad of software DVD players, using both the DVD-ROM and and the ripped movie on my harddrive as sources. I'm currently using a Toshiba 4800 STB fed into the H3D component input and it seems better, but it's still not silky smooth.

My question is - is it possible that the DVD is just encoded in such a way that the pans for that particular DVD are just inherently not totally smooth? I would assume that it's a possible explanation, but was wondering if anyone could say definitively.

Thanks.

-Gene

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Paul_Seng

· #2 · Sep 9, 2003

Gene, there was a thread in the digital PJ's forum about panning. If you do a search there you might find something, but I think some have come to a conclusion that it is the source of the material causing this.

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jkaiser

· #3 · Sep 9, 2003

It may also be a motion compensation issue. I don't know if tomsMoComp can solve it but from what I gathered from the Phillips motion compensation announcement I posted a week or two ago, the following is the norm...

When converting from the DVD which is 29.? or 24 frames per second depending upon video or film sourcing. To make your 60hz (or what ever your refresh rate is) multiple copies of a frame are created and sent out the stream. Now instead of the source frame sequence of ABCDE, your stream sequence may be AABBCCDDEE. This is noticed as on pans since so much is changing. Motion Compensation averages the 2 sequential frames (AB) and creates the sequence (AXB where X is the averaged frame).

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Wireless

· #4 · Sep 9, 2003

I see it at the theater and on my CRT running at [email protected] I think it is source related. Horizontal pans seem more smooth than my previous projector, a DLP, but are still noticable.

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Aaron Oz

· #5 · Sep 9, 2003

Source.

Next time you go to a commercial film projection theater, watch the pans closely. Your eyes will start to water. It's a blurry, micro-stuttering mess.

Our brains have just accepted this for movies and nobody says anything. My HTPC now pans smoother than the theater. I'm not saying they are anywhere near perfect, but the pans are much better than film in the theater.

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littledeath

· #6 · Sep 9, 2003

Quote:

Originally posted by Aaron Oz
Source.

Next time you go to a commercial film projection theater, watch the pans closely. Your eyes will start to water. It's a blurry, micro-stuttering mess.

Our brains have just accepted this for movies and nobody says anything. My HTPC now pans smoother than the theater. I'm not saying they are anywhere near perfect, but the pans are much better than film in the theater.

Lol I agree completely , the first time I noticed this in a theater was while watching DantÃ©s peak ,since then it has become so obvious that some action movies are actually less jerky on the dvd then in the theater for me , funny how also divx makes pans sometimes a lot smoother then on the original dvd ( I guess its part of the encoding) . But blaming it on dvd is certainly not completely right ,IMO the main culprit is 24fps .

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glavs

Discussion Starter · #7 · Sep 9, 2003

Since I've constructed my home theater, I haven't been to a commercial theater, so I haven't had the luxury of comparing. Nonetheless, your comments surprise me. I can understand micro-stuttering due to the nature of digital media being an approximation of the original analog form (encoding). But to hear that film is also jerky is quite a revelation. Are you saying that 24 fps is not enough of a "refresh rate" for human eyes? This can't be a new phenomenon. Is it just that I never noticed it before at the theaters? My screen is much smaller than a theater screen, so I can't imagine that the theater screen would have hid the problems any better.

Very curious indeed.

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tigerdave

· #8 · Sep 9, 2003

Well, it sure is nice to know that I'm not the only one who has noticed this crazy phenomenon. Whenever I'm in the theater, I too get woozy whenever a camera pans. The entire image is just plain blurry.

When "The Blair Witch Project" first came out, I thought I was going to hurl -- right there in the theater.

And did I mention that I can spot any monitor running at 60Hz refresh rate from a mile away? I can even see 75Hz. I try to run all of my PC monitors at 100-120Hz refresh. My eyes have just become too sensitive over the years.

On my Pioneer RPTV, I can see a greenish "ghosting" around certain on-screen images if I quickly look from one side of the screen to the other.

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glavs

Discussion Starter · #9 · Sep 9, 2003

Don't get me started on refresh rates. I can't believe that people cannot see flickering on CRT monitors at 60 or 75 Hz. I need at least 85 Hz before the screen looks stable to me. This is not something that I developed over the years - I've always been that sensitive to flicker.

I wonder if sensitivity to refresh rates is in any way related to the pan stuttering phenomenon we've been talking about.

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e vey

· #10 · Sep 9, 2003

--I can't believe that people cannot see flickering on CRT monitors at 60 or 75 Hz.--

I can't. I believe you when you say you can. I am getting older and maybe that has something to do with it.

My high frequency hearing has been shot for years, so when the audiophiles, get going I just shrug.

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Martin Rendall

· #11 · Sep 9, 2003

I can see 60hz (and get a headache), but not really 75hz, although I think I can A-B 75hz and 85hz, as long as its not a DBT. On the other hand, I can barely detect 72hz. The mind is a wonderful thing.

On an earlier subject, I think that 24fps was chosen as the bare minimum number of frames which would trick humans into perceiving continuous motion. That is, the cheapest it could be done at the time. There's no way that it could be considered optimal.

Look at FPS games like Quake... completely unplayable at 24 fps... starting to get convincing around 90fps, and still not completely smooth at 300fps. Which brings to mind a (severly off topic) question: what good is a quake frame rate greater than the screen refresh rate?!?

Martin.

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littledeath

· #12 · Sep 10, 2003

IMAX HD runs at 48fps , pretty sure they wouldnt be doing it if 24 fps was all thats necessary. Also sometimes on crt monitors certain refreshrates seem to be less annoying at certain resolutions than others which I believe may have something to do with focus . Flat sceen monitors (to me anyways) feel a fair bit more flickerish than the conventional ones but thats somewhat understandable regarding all the extra circuitry need to run them. If you cant see the effects of the low refresh just wave your hand in front of the monitor then set it to a higher refresh. It'll look more solid , just a simple trick

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ICE9

· #13 · Sep 10, 2003

This really bothers me in the theatre. I find it is even more pronounced in movies with alot of digital editing.

Quite often it is a digital pan/scan in the 4:3 version of a movie.

It can also be very pronounced in movies with alot of digital video. For instance, i hated Star Wars Ep1&2 in the theatre because all of the digital editing was designed for DVD framerates. When it was put on film it caused all the large vehicles to have a jittery look to them. When watched on DVD this is not noticeable at all because the original source was the same framerate.

At times I have considered launching a campaign to abolish digital pans.

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glavs

Discussion Starter · #14 · Sep 10, 2003

It seems as though another variable is screen size/distance, no? For instance, I have never seen stuttering watching movies on TV (HBO for instance) on my 27" tv located across the room from my sofa (say, 10-15 feet away). I would imagine that the stutter is still there, just not noticable.

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