Zoom : adding 'no aspect ratio change' in general settings | Page 3

Discussion in 'Improvement Suggestions' started by miljbee, August 4, 2006.

?

Would you like to be able to set up the zoom modes you want to use ?

  1. Yes, because there is some zoom modes that I never use

    99.7%
  2. No thanks, I am actually using all the available zoom modes

    0.3%
  1. miljbee

    miljbee Portal Pro

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    whaoh !
    the King Frodo posted a reply into MY post. :oops:

    no doubt, it's a great day ! thx Frodo !




    More seriously, For the math, i will try to get in this seriously, but it won't be before tonight !

    More generally, detecting real 'interresting' part of the video which is playing is a great idea, but i think it is a quiet different feature than the one i have described (smart zoom).

    the ideal would be to implement both :
    1 - smart zoom to know what type of adjustments a user can accept to have the picture best fit on his screen.

    2 - continuously auto detect 'interresting' part of the displayed video, and eventually adjusting it according to smart zoom parameters (or at least the current selected zoom mode)

    3 - adding mp the ability to remember which zoom mode was used for each video (and channel for tv).


    ... yes, i know, it makes 3 features ....

    if those 3 features were implemented, i think they could address a huge number of post on this forum ....

    Now, i have to return to the post of NLS to fully understand it, wish me good luck !
     
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  3. NLS

    NLS Portal Pro

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    :D

    We should do work on this. I will get back tonight too.

    Aspect Ratio adaptability is a major issue in video display, yet, not touched "professionaly" even by... prosfessionals.

    We can change this it is not the Theory of Chaos nor the Theory of Relativity.

    :)

    cu l8r.
     
  4. miljbee

    miljbee Portal Pro

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    ok NLS, i hadn't understand the smart expand/shrink feature, but now that i have carefully re-read your post, that is clear to me.

    I have never heard of such a feature, and i would be interrested in viewing what it can produce.

    do you know an "easy to set up" free soft that can do this so we can evaluate the functionnality ?

    concerning the curve sin, how to define the end point ? i mean how to decide the max shrink/expand value to apply ? this is a quiet difficult parameter to understand. i don't think this can be ask to the user ... if it is arbitrary decided, then there will alway be some modification request. wouldn't it be possible to include this parameter into the zoom box to present the resuklt directly to the user ?
     
  5. knutinh

    knutinh Portal Pro

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    So, you've got a display with pixel ratio 4:3 but aspect ratio 3:4? That would make it taller than it is wide, but still having the usual 800x600 resolution? Also, you've got a standard 1080p 16:9 video stream. 14:9 implies that you want to do a little stretching so as not to make the 16:9 picture too small on that weird screen.

    No cropping means that 1920 pixels should fit into 800 horisontal pixels. That means scale down horisontally by 2.4.

    Now, we have 1080 vertical pixels that should fit within 600 vertical display pixels. However, we have to keep in mind the various ratios. We want 14:9, and the display is 3:4 aspect. As we have filled the width, we must fill the height by 9/(14/3) = 1.93 or about half the 600 pixels.

    (3/4)/(14/9) = 0.4821 is the ratio between display and desired AR

    We need to fill 0.4821*100 percent of the image vertically, or 289 pixels in order to have a 14:9 visual image.

    300-289/2 = 156
    300+289/2 = 445

    Video source rect would be [1 1920 1 1080] (x1, x2, y1, y2)

    Display rect would be [1 800 156 445] (x1, x2, y1, y2)

    We are filling 100% of the available display width and 48% of the height. As the display AR is 0.75, we see that we have a visual AR of ((3/4)*(600/289)) = 1.5571 where the goal was 14:9 = 1.5556

    -k
     
  6. NLS

    NLS Portal Pro

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    No this is NOT something that will be configurable by the user. This is pretty standard in all 16:9 TV (haven't you seen any?).

    No I don't think there is any easy to setup free soft that does it. I am not sure if either progdvb or mytheater does this (I think it was one of the two... not sure though... maybe some other dvb software).

    Anyway the idea is something like that (made in MS Paint in 5 min):

    [​IMG]

    i.e. you leave the center (the action area) normal (so actor heads won't show "wide" etc.), while as you move further to the edges it is streched more and more.

    In practice it works so good that many times you are not sure if a film is indeed 16:9 or stetched. Even circles that are near the centerer still look circles, while circles that are closer to the edge are "soft" deformed (and not much) so you may not even notice it.

    As I said, MP should decide that resize formula (staticaly, just based on source and destination sizes) and is nothing for the user to configure.

    You probably have seen in in 16:9 TV. If not, visit a friend or a shop and try it. :)
     
  7. knutinh

    knutinh Portal Pro

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    You seem to like these tall displays! =)

    We've got a 0.9 AR display with 1.33:1 AR video in and 1.33:1 desired AR (no visual stretching). I cant see that the supplied info tells whether to use source cropping, so Ill assume that it isnt desired.

    720x576 pixels representing a 4:3 visual image should be presented on a 1024x768 pixel display that has visual dimensions 0.9:1. It is evident that we need som goode ol' black bars.

    (4/3)/(0.9/1) = 1.4815

    This is the visual relation between source video and output display. In order to fit a "wide" (4:3) image inside the nearly rectangular 0.9:1 monitor we need to fill the height with information only 1/1.4815 of the available height, or 67.5%. When there are 768 available pixels, we should employ 518 vertical pixels and 1024 horisontal ones.

    video source rect : [1 720 1 576]
    display rect : [1 1024 125 643]

    -k
     
  8. miljbee

    miljbee Portal Pro

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    if it's true, and i believe you, then mp should definitively implement that !

    then, one more question has to be added to the smart zoom config :

    the user preferences would be simple questions :

    would you accept some aspect ratio modifications to display a picture ?
    A:Yes, B:No, C:Yes but limited
    if C, enter the max aspect ratio error you would accept : C%
    (if A, C=100%, if B, C=0%)

    would you accept to lose (crop) a part of the picture ?
    at the top and bottom of the screen ?
    D: Yes, E: No, F:Yes but limited
    if F, enter the % of the height you accept to lose : G %
    (if D, G=100%, if E, G=0%)

    at the left and right of the screen ?
    H: Yes, I: No, J : Yes but limited
    if I, enter the % of the width you accept to lose : K %
    (if H, K=100%, if I, K=0%)

    Would you allow smart expand/shrink (and a link to explain the feature) ?
    M:Yes - No

    please sort by preference order the action that mp should take to compute smart zoom :
    - crop
    - smart expand/shrink
    - AR change

    This way, we could have a 4:3 picture filling nearly a whole 16:9 screen with very little deformation. This would really be a very special MP feature.

    perhaps that for a tech preview, all this params could be set to some default "hardcoded" value. if they are all combined together, you don't need huge values for all of them, and this could do the trick without confusing the user about what percent of AR or picture he whish to lose.

    Perhaps we could start with
    Crop : 10% Max
    Smart Expand/Shrink on
    AR modification : 5% max

    the algo would select these parameters in this order.

    now the maths that will enable smart expand/shrink need to be defined more precisely. anyone has an idea ?
     
  9. knutinh

    knutinh Portal Pro

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    The problem with that kind of progressive distortion is that certain programs looks very bad. For instance discussion programs with a panel of people, the poor guys sitting at the sides will have enormous heads =)

    What about distributing the distortion over all possible grounds?:
    1. Some clipping top and bottom (14:9 is often possible)
    2. Some compression/stretching of the entire image
    3. Some non-linear stretching, most on the sides
    4. Leave some black bars

    This sounds like the most sensible compromise to me if one wants to fill as much as possible screen estate with a 4:3 signal or vica verca.

    -k
     
  10. jawbroken

    jawbroken Portal Pro

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    Personally I hate that progressive distortion thing. I don't mind giving up the sides of my screen to view 4:3 video on my 16:9 screen. When a camera pans or tracks sideways with progressive distortion it ripples and gives me a headache. But as long as you can turn it off that is fine.

    But I think this topic is more about aspect ratios and user defining or automatically scaling, not non-linear distortion operations like progressive distortions that, I imagine, are a lot harder and more processor intensive than scaling and shifting.
     
  11. NLS

    NLS Portal Pro

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    indeed

    being ugly in the minds of some people and being CPU intensive for those who want to use it, doesn't mean it shouldn't be implemented

    people that like it (and can "afford" it) will use it... the others won't

    ALL 16:9 TV on planet Earth right now implement this feature. So it must be nice to some people (I know I always see TV like that and yes the guys near the edges look weird :) ...but since I am not one of them, I don't care... after all who cares about "video clarity" in a discussion show hehehe)
     
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