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8th February 2006, 18:46 | #1 | Link |
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Aspect Ratio Signalling (ARS) Calculation Tool
In response to all those people who have enquired about how to calculate the required, aspect ratio signalling (aka: PAR, SAR and DAR) values for their "anamorphic" encodes. And how to correct the aspect ratio of their existing "square pixel" encodes.... I have conceived the first version of my ARS Calculator (see link below).
What's it for? Essentially, if you have an encode that's displayed at the wrong shape (see the port-hole).... like this say: - [IMG][/IMG] .... The ARS calculator will enable you to work out the required "Aspect Ratio Signalling" (ARS) value needed to correct the shape.... to this say: - [IMG][/IMG] How do I use the ARS Calculator? First: You need to determine the "Pixel Frame Size (PFS) of your MPEG-4 encode - Preferably without the black mattes. Second: You need to determine the actual aspect ratio of the movie. Known as the, "Movie Aspect Ratio" (MAR). This can often be found on the back of the DVD cover, or on Amazon. Third: You enter both these values into the "ARS Calculator" and then press the "Calculate" button to obtain the required "Aspect Ratio Signalling (ARS) value. Here's an example: - [IMG][/IMG] What do I do next with this ARS value? You will need to use another application called MPEG4 Modifier First: Feed (drag and drop) your MPEG-4 source into MPEG4 Modifier. Second: Enter your "ARS value" into the "Custom" boxes (as shown below). Third: Press the "Save..." button. Please Note At the time of writing both applications require Micro$oft's .NET Framework 2.0 in order to run. Anyway..... I hope you will find a use for it Cheers With Thanks My profound thanks goes to Moitah. Who was able to turn my design concept into a working reality. Many, many thanks mate
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Last edited by SeeMoreDigital; 9th October 2019 at 22:35. |
11th February 2006, 11:38 | #2 | Link |
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hm shouldnt it for a standard dvd encode (cropped or not) never be necessary to use a custom par?
btw why do you introduce new ar names and not use simply the already known ones, like pixel frame size -> resolution movie aspect ratio -> display aspect ratio aspect ratio signalling -> pixel aspect ratio
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11th February 2006, 12:32 | #3 | Link | |
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Quote:
In the case of MPEG-2 DVD images, the "theatrical" aspect ratio of the source movie (Movie Aspect Ratio) does not necessarily relate to the Display Aspect Ratio of the disc! The source movie could have a "theatrical" aspect ratio of say, 1.33:1, 1.771, 1.85:1, 2.35:1, 2.40:1 etc, etc. But the DVD disc will have a display aspect ratio of either 1.33:1 (4:3) or 1.77:1 (16:9). Whether it be PAR, SAR, DAR... at the end of the day they are all forms of "Aspect Ratio Signalling" Cheers
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11th February 2006, 12:33 | #4 | Link |
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whats the difference between movie and disc aspect ratio???
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11th February 2006, 12:56 | #5 | Link | |
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However, the DAR signalling levels will be different for PAL and NTSC disc's because they offer different resolutions (or pixel frame sizes). Think of it this way, the image element (which is theory can be any aspect ratio) is laid over a fixed pixel sized background of either 720x576 or 720x480 pixels
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Last edited by SeeMoreDigital; 11th February 2006 at 13:01. |
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11th February 2006, 13:10 | #6 | Link |
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so the point of your tool is to allow the user to find a par that is better fitting the movie than the standard dvd 4:3/16:9 pal/ntsc one?
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11th February 2006, 14:01 | #7 | Link | |
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When cropping the black mattes away, it's not always possible to obtain the "theatrical" aspect ratio, within the confines of a "mod16" encode. For example, an anamorphic (16:9) widescreen NTSC DVD with a 2.35:1 movie on it.... like this one: - ... "should" mathematically contain an image of 720x363 (give or take a few vertical) pixels... like this: - However, the nearest "mod16" pixel calculation is 720x368.... so it's five vertical pixels out. Admittedly five vertical pixels is not very much at all.... but in reality, the movie aspect ratio quoted on the back of the DVD cover can often be quite a bit out. And in the case of some DVD's.... miles out. Plus the boundary between the matte and the image could be really messy (noisy)! Here's what I do first Before generating an "cropped and resized" encode, I often find it useful to establish the actual aspect ratio of the "image" element on the disc. Using the following method: -
Cheers
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Last edited by SeeMoreDigital; 12th February 2006 at 11:37. |
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11th February 2006, 15:22 | #8 | Link | |
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Quote:
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Between the weak and the strong one it is the freedom which oppresses and the law that liberates (Jean Jacques Rousseau) I know, that I know nothing (Socrates) MPEG-4 ASP FAQ | AVC/H.264 FAQ | AAC FAQ | MP4 FAQ | MP4Menu stores DVD Menus in MP4 (guide) Ogg Theora | Ogg Vorbis use WM9 today and get Micro$oft controlling the A/V market tomorrow for free |
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11th February 2006, 16:23 | #9 | Link |
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Hey, I've got an anmorphic encode of Flight Of The Phoenix. Just for confirmation which out of these would be correct (i.e. - give the AR closest to 0% error):
1:1 option in GKnot chosen - cropped down to 720x432 (if I switch to square or PAL anamorphic (16:9) option is says 2.370 is the AR) Have tried: 1. Giving PAR of 2.35:1. On playback I get 1016x432 (using MPlayer) 2. Giving PAL (16:9). On playback I get 1048x432. 3. Calculating 720 x 432 by MAR (2.35:1) using ARS (141:100). On playback I get 1016x432. Should I not just be using the DAR GKnot gives? So 720 x 432 by 2.37:1 (155:109) or something? Last edited by Backflip; 11th February 2006 at 17:01. |
11th February 2006, 16:34 | #10 | Link | |
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Quote:
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12th February 2006, 06:00 | #11 | Link |
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The 720x432 encode with ARS @ 155.109 looks closest for me.
Interesting one though, I did a rip myself of Sith a while ago and only got (1:1) - 704x416 (0.0% AR error, w/ AR indicated as 1.692) or (PAL anamorphic (16:9) w/ AR indicated as 2.407) - 704x288. This was with all black and messy edges cropped out I think. |
12th February 2006, 13:27 | #12 | Link | |||
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Hi everyone!
Interesting thread, like SeeMoreDigital said: Quote:
Quote:
Just thought of sharing this as i find this tool extremely usefull when finding out the aspect of the movie and which resolution to use on my divx conversion. Ricardo Ps: Another neat function is that it can make an avisynth script based on the cropping made manually, example: 1- rip your "main movie"from your dvd to your Pc and use Dgindex to creat a d2v script 2- open aspect, click on the Aspect ratio dropdown menu and select "advanced" 2- click on open and select "d2v project" and delect the d2v script, manually crop and click on ok. 3-back on main menu select autosize and it wiil find the best resolution, click on "save" and it wiil produce an avisynth script based on the cropping you made that can be "fed" on to virtualdub to convert to divx/xvid without going in to the filters section, just select the codec and you´re away. Quote:
Last edited by ricardo.santos; 12th February 2006 at 14:26. |
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12th February 2006, 14:40 | #13 | Link |
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Thanks for that ricardo.....
I like that it's able to physically introduce a visible (red) matte over the existing black matte, while providing a "Target AR" at the same time... That's very useful It's a shame you have to navigate thru' so many options (ie: the "Aspect Ratio" down-arrow, the "Advanced..." option and then click on the "Open" button) to bring up the "Video Window": - It would have been much easier to have a tool which immediately opens a "video window" and allows you to drag and drop different types of video formats Cheers
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12th February 2006, 15:31 | #14 | Link | ||
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Quote:
Quote:
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13th February 2006, 11:15 | #15 | Link | |
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Quote:
the bests y ps. i'm w/bond here. he's right (as usual). cropping doesn't affect anything if par is used for resizing. of course, badly tailored dvd-s are of different kinds. (i have some of them ) |
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18th February 2006, 21:08 | #16 | Link | |
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Quote:
The objective is to find the correct "aspect ratio signalling" (PAR) value... Cheers
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Last edited by SeeMoreDigital; 18th February 2006 at 21:11. |
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12th February 2006, 20:22 | #17 | Link |
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Could someone plz approve ARS Calculator? I'd like to try this out
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19th February 2006, 00:57 | #18 | Link | ||
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Quote:
Perhaps i should reiterate the question of Bond which you refused to answer: Quote:
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19th February 2006, 01:25 | #19 | Link |
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Actually Bond did make another response, confirming my obsevations but removed it before I could respond....
But before answering the question in more detail I must enquire as to whether you accept that software media players display MPEG-2 DVD's in accordance to the ITU specs, or not. I would respectfully ask you to play a DVD in you favourite software DVD player and make a full screen grab of what your display sees.... because what your display sees, is what you see. You could even play a DVD in VLC player and capture what it see's! Then please post these images here and we will work out their aspect ratios. It would also be helpful if you elevated the brightness level in your media player before making a full screen grab, so we can work out where the DVD matte meets the black of your 4:3 monitor.... Like this say: - Cheers
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19th February 2006, 02:30 | #20 | Link | |
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Ok, i will give you an example. Imagine a screenshot from a dvd (720x576 with DAR 16x9), and the actual picture (without black borders) is 720x432. |
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