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Old February 10th, 2011, 05:01 PM   #16
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If you follow my link...

If you follow the link that I provided above, you can find detailed explanations by many folks, including Chris and Trish Meyer. Chris evens tells how to "make it all go away" and use the old, wrong values.
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Old February 11th, 2011, 02:40 PM   #17
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Originally Posted by Ernesto Mantaras View Post
cropping 13 pixels off the top and bottom would only make the image end up even thinner..
When you crop off the top and bottom and the picture is set to scale to fit it will make itself fit the screen vertical. The black lines will now be outside the frame. Just try it.
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Old February 11th, 2011, 05:43 PM   #18
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Ann, you're right, that cropping thing worked to eliminate distortion (I had thought Harm meant to crop on export, not on AME, I'm sorry Harm! read it wrong). The problem is it's actually taking away info unnecesarily (well, it's necessary to bypass this problem, but it's a shame to be forced to erase part of my video to be able to expor to DVD).

Dave, thanks for your answer. The source image is a 1920x1080 video, and output to a 720x576 with 1.46 PAR. Please try to encode an HD video to widescreen PAL DVD and you'll get that exactly (unless the 26 vertical pixels are cropped...).

And about video cameras capturing 16.45:9 images... Why do you say that? I've never seen distorted images coming from them when editing with the "wrong" PAR. And how would that work on any HDV camera? You record HDV which is 16:9, then capture it in DV format and you have to watch it stretch while editing?
Or, put another way, when you watch that footage on a regular TV, your watching horizontally stretched material then?
I mean, really, you are saying that TV has always been 16:45:9 and hiding tiny portions of the sides by stretching the image to then show a real 16:9 image? (well, underscan takes away a lot more, but that's another story). Why is my "Scott Pilgrim vs. the World" DVD have a filled image instead of being sitting in the middle with two black bars on the sides (it's not because of the 1.85:1 aspect ratio working ala 13 pixel cropping, mind you...).

I sound and feel stubborn. But I feel like I'm not being understood at all.
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Last edited by Ernesto Mantaras; February 11th, 2011 at 06:09 PM. Reason: Mistake when naming other users
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Old February 11th, 2011, 05:52 PM   #19
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Todd, thanks. But the problem isn't in After Effects. I work in HD (I'll take note of the link if I have to do an SD comp). The problem comes when exporting to SD DVD, so it's Adobe Media Encoder that causes the big hassle right now. I mean, I can use ProCoder (have been using it for a long time now). It's just that AME looks better to me. Much less blurred, it holds a lot more detail from the HD source.
Oh, and I had noticed this problem once I exported an HD project directly to DV. There were the black bars, and it seemed quite odd, but it's only now that I realized why that was.
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Old February 11th, 2011, 07:40 PM   #20
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Originally Posted by Ernesto Mantaras View Post
...................................................

Dave, thanks for your answer. The source image is a 1920x1080 video, and output to a 720x576 with 1.46 PAR. Please try to encode an HD video to widescreen PAL DVD and you'll get that exactly (unless the 26 vertical pixels are cropped...).

And about video cameras capturing 16.45:9 images... Why do you say that? I've never seen distorted images coming from them when editing with the "wrong" PAR. And how would that work on any HDV camera? You record HDV which is 16:9, then capture it in DV format and you have to watch it stretch while editing?
Or, put another way, when you watch that footage on a regular TV, your watching horizontally stretched material then?
I mean, really, you are saying that TV has always been 16:45:9 and hiding tiny portions of the sides by stretching the image to then show a real 16:9 image? (well, underscan takes away a lot more, but that's another story). Why is my "Scott Pilgrim vs. the World" DVD have a filled image instead of being sitting in the middle with two black bars on the sides (it's not because of the 1.85:1 aspect ratio working ala 13 pixel cropping, mind you...).

I sound and feel stubborn. But I feel like I'm not being understood at all.
Ernesto, I don't think you are being stubborn and I DO understand, honestly. I am trying to find a way to clearly explain but obviously failing so far...... which is MY problem, not yours !

This situation only applies to standard definition, and I am sure you will understand it completely if you can bring yourself to accept the following statements.......

The image that is intended to be seen by the viewer as a 16 x 9 image is contained in the central 702 x 576 section of a 720 x 576 digital file.

The 9 pixel wide strips at each side were never intended to be seen by the viewer.

........ now, since all this was developed, we have got loads of devices (like computers) that let us look at the whole of that 720 x 576 file, and we now see those two strips which we were never intended to see. If you watch that digital video on domestic television equipment you should not even see the 9 pixel wide strips at the left and right.


To complicate matters, when cameras started to record to SD digital formats in widescreen, they tended to fill the whole 720 x 576 with picture, but still only the central 702 x 576 section was the 16 x 9 image destined for the viewer..... the 9 pixels at each side were never intended to be seen.

Now lets come to your test frames. You have just said that these are downsized HD.

Well, HD is true 16 x 9 and goes from top to bottom and side to side of a 1920 x 1080 digital file.

....so you can see that, if what I say is true, it will correctly downsize to the central 702 x576 area of an SD digital file.... and leave the two black bars that are never intended to be seen. That is what you got.

The points I've made (sorry if I've sounded a bit heavy handed in my explanation) are mentioned in the links that Todd sent you, and I would recommend reading some of those as well.

If you get a spare moment, you could try a small test. Make a short DVD test of your resized HD, complete with black bars at the sides, and look at it on a conventional TV, played from a conventional DVD player, and see if you see the black edges... in theory you should not.

I am going to go and do that same test myself now and will let you know what I see.....

Hope this might help explain a bit.

dave

( ..we'll discuss "Scott Pilgrim vs. the World" another time....d. )
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Old February 12th, 2011, 12:11 AM   #21
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Thanks for your thorough response, Dave.

I think I understand the basics of it all, but what bothers me is this: have we worked on distorted images all this time? Because what I get from what you say and what I've understood of the readings, is that SD never shot real 16:9, it was always that little more. And if that''s so, I've always edited with an aspect ratio that shrunk my images horizontally but I never noticed it. And the PAR applied by programs like BSPlayer and Media Player Classic was wrong too. And the only real image I was getting was from playing my DVDs or DV cams on the TV, which stretched the image that little more to make it look right. It's only now that it has been fixed and we're back on track with a 16.45:9 image on DV like it was always meant to be seen. Is that right?

It was never the black bars that bothered me. I know I won't see them on a TV screen because of the underscan, and I don't care about seeing them on a monitor, so long as the image isn't distorted, and that's what I've been getting from playing the DVD files on my computer. Perhaps I can't tell the difference when watching the image on a TV? (coincidentally I had to record a DVD yesterday to show some short films on a film festival of sorts, and got to "test" it)

Again, it's the distortion that I see that bothers me! Because if every playing device I know played the footage on a 16.45:9 aspect ratio (1.46 PAR) the image would be faithful to the original, but what I see is the old 1.42 PAR, the 16:9 aspect ratio for DV and DVD, and so the image, now sitting in the middle, in that 702x576 area, looks squeezed.
By the way, considering that, I'll have to refrain from the 13 pixel cropping. It doesn't fix the problem, it only fills the black sides. To fix the problem, like I once said (and then got lost) is to squeeze the image vertically leaving two black stripes on the top and bottom, thus ending with an apparently scaled down 16:9 image (all this if all the media players play the material in a 1.42 PAR, like I -perhaps- wrongly think).

So, do DVD players as well as cameras display/record a 16.45:9 image with the 16:9 one sittting in the middle?

Please, after we clear this whole thing (if we ever do) let's talk about Scott Pilgrim! :P
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Old February 12th, 2011, 01:47 AM   #22
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Thanks for your thorough response, Dave.

I think I understand the basics of it all, but what bothers me is this: have we worked on distorted images all this time?
If your source image was from an SD camera and you didn't stretch it, compress it, rotate it etc. ....and then you output it to a DVD or back on to tape, then no, you probably haven't been working with a distorted image.

The thing to think about here is how the footage is interpreted and what are the settings of the composition. If the imported SD widescreen is interpreted under the old Adobe rules and used in a composition that is also set to the old Adobe rules then the image will not have been dimensionally distorted at all. It will travel through the system intact, it's the final display system that will not show the edges of the shot , but that is OK because the camera was taking the shot "knowing" that those edge bits were off the side of the display. All is correct.

Let us imagine that the shot has a large, perfectly circular clock face in the middle of shot. That would be displayed correctly as circular. ...so what's the problem?

If you now rotate the shot by 90 degrees the circular clock face would no longer be a perfect circle because the AEs maths are wrong.... and that's because it's working with an inaccurate pixel aspect ratio.

A different example... same shot of the clockface (not rotated or anything) ..looks fine. You now import a square pixel graphic of a white circle on black. It is interpreted as square pixels. You add it as a layer at 50% transparency over the clock shot and try to match it to the clock face. You'll find it won't quite fit because it is oval..... the maths are wrong because of the inaccurate pixel aspect ratio in the composition settings.

If you repeat these two exercises with the new Adobe settings (both interpreting the footage and for the composition settings) all of it would work correctly.

Quote:
Because what I get from what you say and what I've understood of the readings, is that SD never shot real 16:9, it was always that little more.
Think of it more that the SD camera shot it 16 x 9 plus a little bit more picture at the sides... and that bit more picture is going to get cropped off when it is displayed on a 16 x 9 television, leaving you with a genuine unsquashed and unstretched 16 x 9 picture. This is what happens for video going straight from the camera to the screen.... part of the "system" and nothing to do with After Effects.....except that you need to know it's there! ...and the pixel aspect ratio numbers need to know it's there as well !

Quote:
And if that''s so, I've always edited with an aspect ratio that shrunk my images horizontally but I never noticed it.
If you've followed what I said above, you will understand that is not necessarily the case. If the input is genuine SD footage and the interpretation is THE SAME as the composition settings, then the footage may well have survived the trip intact even if the PAR numbers were wrong.... any errors might have show up in different ways, as I explained above.

I will reply to the rest of your points later as I have to go now..... but I will say I have no detailed experience of BSPlayer or Media Player Classic so can't really comment on them.....

..anyway, Part 2 to follow....

dave

Last edited by Dave Jervis; February 12th, 2011 at 02:19 AM.
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Old February 12th, 2011, 07:01 AM   #23
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I guess this all went wrong when they decided there should be black bars along the side... the logic left back then... leaving us with an avalange of seemingly random numbers :-p

But in the end you can always place your true 16:9-(HD)footage in a wider BBC-PAR-sized composition.
Or export your SD project for web as a true 16:9 by cutting the edges in a new composition or during export.
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Old February 12th, 2011, 10:00 AM   #24
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hahaha Yeah, it almost seems as if all that extra math was put in there to prevent outside people to take over production on the BBC. :P

I have no problem with placing the 16:9 image in the BBC PAR video! I'm ok with black bars, always have been since letterbox. Where I do have a problem, however, is in the fact that what I see when playing the footage (at least digitally, maybe far from a computer monitor, on a TV I never noticed) is distorted. Because like I mentioned, BSPlayer, Media Player Classic, I believe that Windows Media Player and the program I used to use to encode (ProCoder) all use the 1.42 PAR. I guess they all followed the Adobe standard and now are all screwed up and they'll have to catch up?

DVD's in my case are only for delivery, to be played on DVD domestic DVD players that will be watched through a regular TV and a projector, but lately quite more often also on LCD TVs... If anyone can actually confirm that all these devices actually play the footage with the (now) correct BBC 1.46 PAR, then everything's OK, because digital delivery is controlled h264 anyways, so no PAR issues to be found there when coming from HD.
But I'm rethinking now about all my SD short films that I encoded on a 720x404 resolution...

Dave, thanks again for taking the time to answer with such care! Yeah, I read the Chris Meyer article and saw that wheel example. The distortion worry I mentioned had to do more with working with and staring at a distorted image while editing for years, and designing a bunch of graphics that will now look distorted under the BBC PAR (perhaps my footage wheel is perfectly rounded now, but whatever digital wheel I may have made is now oval... )
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Old February 12th, 2011, 03:33 PM   #25
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If your dvd plays ok on the pc and distored on tv check the settings of the dvd player and the tv.
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Old February 12th, 2011, 05:15 PM   #26
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All the computers I remember watching DVDs on play it with a 1.42 PAR, which to me always seemed to look right, thinking that the images were 16:9 images. What looks distorted to me is the HD footage encoded to DVD on AME, like what I showed in the image, because it's encoded with the 1.46 PAR but then played everywhere with a 1.42 PAR.

My DVDs played on a regular DVD player and a regular TV look alright. Because they seem to play on a perfect 16:9 aspect ratio, but maybe there's always been that .45 extra stretch that justifies those black bars on the sides for real 16:9 footage. That's exactly what we're talking about. I'm just now discovering that DV 16:9 was never 16:9!

So, it all boils down to confirming whether or not DVD players, projectors and media player programs know this as well. Because at least in PC (as far as I've seen) they all play the footage in 16:9, 1.42 PAR. It's easily to notice on a 16:9 monitor: the image fills the screen, instead of leaving two little bars on the top and bottom (kinda like 1.85:1 film would).
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Last edited by Ernesto Mantaras; February 12th, 2011 at 05:31 PM. Reason: Accuracy of concepts.
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Old February 12th, 2011, 07:17 PM   #27
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Hi Ernesto, ...a briefer post from me this time as it's clear you have a pretty full understanding of the situation now......

You have asked an important question though..... how much of the hardware and software uses the "correct" values for pixel aspect ratio.... I think it's true to say you will encounter systems that use both the old and new values. I know this isn't very satisfactory but I don't get too stressed about it myself for four reasons....

1. The people who see and compare the differences on several systems tend to be in the business and aware of the issues. Many end users will see results on just one system and accept it as accurate. If the "industry" tries to get it so that it look right on the domestic viewing systems, then that is probably a good situation to aim for. This is not a defence of the unsatisfactory state of things, just an observation.

2. The magnitude of the possible error is in the region of a 2.5% stretch or squeeze. A tube television from 20 years ago probably had width and height controls somewhere that could easily be set to a worse error than 2.5%. If there are 4 people sitting side by side watching a TV, the two on the ends will be looking at the screen from an angle that could easily distort the perceived "width" of the picture by that kind of amount... and I try not to think about the view from the end seat in the front row of a cinema! Any error is "wrong", but just how "wrong" is it....

3. Awareness of this issue will prompt people (...us..! ) to try to find a way of delivering the most correct version to the end user... ( I am hoping that's what we are doing dicussing this here...now....)

4. It applies to SD only.... and, in time, this issue is just going to disappear as HD, BD and a range of more sopisticated computer and internet delivery systems take over the universe.... Anyone for holographic 3D video ... I've just been watching a prototype on TV... ?

regards

dave
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Old February 12th, 2011, 10:52 PM   #28
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Originally Posted by Ernesto Mantaras View Post
All the computers I remember watching DVDs on play it with a 1.42 PAR, which to me always seemed to look right, thinking that the images were 16:9 images. What looks distorted to me is the HD footage encoded to DVD on AME, like what I showed in the image, because it's encoded with the 1.46 PAR but then played everywhere with a 1.42 PAR.

My DVDs played on a regular DVD player and a regular TV look alright. Because they seem to play on a perfect 16:9 aspect ratio, but maybe there's always been that .45 extra stretch that justifies those black bars on the sides for real 16:9 footage. That's exactly what we're talking about. I'm just now discovering that DV 16:9 was never 16:9!

So, it all boils down to confirming whether or not DVD players, projectors and media player programs know this as well. Because at least in PC (as far as I've seen) they all play the footage in 16:9, 1.42 PAR. It's easily to notice on a 16:9 monitor: the image fills the screen, instead of leaving two little bars on the top and bottom (kinda like 1.85:1 film would).
I am trying to understand the issue here. I exported a full TIFF sequence from Premiere to Encore and authored a PAL DVD (16:9). But it plays back fine on every kind of player. I don't see bars on the sides ever, nor the top and bottom. I used CS3.

Is the difference between 1.46 and 1.42 negligible?
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Old February 13th, 2011, 12:15 AM   #29
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I am trying to understand the issue here. I exported a full TIFF sequence from Premiere to Encore and authored a PAL DVD (16:9). But it plays back fine on every kind of player. I don't see bars on the sides ever, nor the top and bottom. I used CS3.

Is the difference between 1.46 and 1.42 negligible?
You don't see any difference because the PAR was changed in CS4, it's still the same in CS3. The difference small but can be noticed.

Dave, I agree with you on the fact that it's perhaps not a big deal, specially with the death of SD. Well, it isn't that much of a big deal, really... But I'm usually very careful with everything regarding getting the image right and not being able to have control over that frustrates me. Not finding any logic on the whole issue made it even worse.
But I guess I can live with a little distortion if the DVDs are ever played on PCs (at least until players and editing programs catch up).

On TVs, first off I'll hope they all follow the BBC specification (if anybody knows anything about that specific subject, please comment). And if they don't, I know 98% of the people watching my stuff won't ever realize there's any 2.5% distortion going on on the image. After all, I never noticed it if it was there while I authored full framed 16:9 DVDs... Or any non BBC standard PAR DVD, let's say...

So, no more worries about the black bars on the side and the possible distortion on some playing devices and/or programs, I guess. :P
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Old March 4th, 2011, 06:55 AM   #30
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Re: CS5's PAL 16:9 aspect ratio is WRONG

I agree with Ernesto and think that this change is seriously stupid. DVD's have been 1.42 for ages, the've all shown perfectly and we've been making dvd's for a long time without any problems.

But now we are forced to add black bars to the side of video because BBC uses 702x576?

Also ALL of our other applications (3d etc) tend to work in 1024x576. Try to squeeze that in.

Awesome.
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