Zoom do not keep aspect ratio (3 Viewers)

[fer2]

I have a 16:9 screen and the zoom feature (also zoom14:9) is fundamental to see movies from TV channels (fake 16:9 letterbox, etc).

I found that something is wrong with these two zoom modes in MP since the aspect ratio is lost and some vertical enlargement apears. I tried different resolutions, crops, and screens adjudstments (of course to get a squared box). Everything is well scaled for 4:3 but not for the zoomed versions. It is like an internal scale factor is wrong for these modes.

Did anybody notice this? May be I'm doing something wrong??

I'm using the SVN from april the 10th 2007.

Thank you!!!

 

[daniel_1980]

I noticed this at least 1/2 year ago, and it is still the same (with every codec I tried). I think in the zoom modes the PAR is not considered when playing 4:3 content.

 

[lkuech]

Hi all.

I have taken a look into the source code. I looks like the "zoom" mode works a little bit different depending on several parameters (like screensize and videosize).

Can you please post a snippet of your log file after switching to the "zoom" mode?

The result for example may look like this:

[Info.][5]: PlaneScene: crop T, B  : 10, 10
[Info.][5]: PlaneScene: crop L, R  : 13, 13
[Info.][5]: PlaneScene: video WxH  : 768x576
[Info.][5]: PlaneScene: video AR   : 768:576
[Info.][5]: PlaneScene: screen WxH : 1284x721
[Info.][5]: PlaneScene: AR type    : Zoom
[Info.][5]: PlaneScene: PixelRatio : 1
[Info.][5]: PlaneScene: src        : (13,83)-(755,494)
[Info.][5]: PlaneScene: dst        : (0,0)-(1284,721)

Maybe that will help us to understand what if the zoom mode does not what it should

Bye
Lars

 

[daniel_1980]

I will post in the evening, if I don't forget.

 

[daniel_1980]

NORMAL:
-------
2007-04-18 17:59:36.671875 [Info.][12]: PlaneScene: crop T, B : 2, 1
2007-04-18 17:59:36.671875 [Info.][12]: PlaneScene: crop L, R : 12, 9
2007-04-18 17:59:36.671875 [Info.][12]: PlaneScene: video WxH : 768x576
2007-04-18 17:59:36.671875 [Info.][12]: PlaneScene: video AR : 768:576
2007-04-18 17:59:36.671875 [Info.][12]: PlaneScene: screen WxH : 666x499
2007-04-18 17:59:36.671875 [Info.][12]: PlaneScene: AR type : Normal
2007-04-18 17:59:36.671875 [Info.][12]: PlaneScene: PixelRatio : 1,3299
2007-04-18 17:59:36.671875 [Info.][12]: PlaneScene: src : (12,2)-(759,575)
2007-04-18 17:59:36.671875 [Info.][12]: PlaneScene: dst : (387,91)-(887,590)


....

ZOOM:
-----
2007-04-18 17:59:43.125000 [Info.][12]: PlaneScene: crop T, B : 2, 1
2007-04-18 17:59:43.125000 [Info.][12]: PlaneScene: crop L, R : 12, 9
2007-04-18 17:59:43.125000 [Info.][12]: PlaneScene: video WxH : 768x576
2007-04-18 17:59:43.125000 [Info.][12]: PlaneScene: video AR : 768:576
2007-04-18 17:59:43.125000 [Info.][12]: PlaneScene: screen WxH : 1024x768
2007-04-18 17:59:43.125000 [Info.][12]: PlaneScene: AR type : Zoom
2007-04-18 17:59:43.125000 [Info.][12]: PlaneScene: PixelRatio : 1,3299
2007-04-18 17:59:43.125000 [Info.][12]: PlaneScene: src : (12,97)-(759,479)
2007-04-18 17:59:43.125000 [Info.][12]: PlaneScene: dst : (0,0)-(1024,768)

 

[fer2]

This the log for my modes:
NORMAL:
2007-04-18 19:57:25.781250 [Info.][14]: PlaneScene: crop T, B : 0, 0
2007-04-18 19:57:25.781250 [Info.][14]: PlaneScene: crop L, R : 0, 0
2007-04-18 19:57:25.781250 [Info.][14]: PlaneScene: video WxH : 768x576
2007-04-18 19:57:25.796875 [Info.][14]: PlaneScene: video AR : 768:576
2007-04-18 19:57:25.796875 [Info.][14]: PlaneScene: screen WxH : 763x595
2007-04-18 19:57:25.796875 [Info.][14]: PlaneScene: AR type : Normal
2007-04-18 19:57:25.796875 [Info.][14]: PlaneScene: PixelRatio : 1,3996
2007-04-18 19:57:25.812500 [Info.][14]: PlaneScene: src : (0,0)-(768,576)
2007-04-18 19:57:25.812500 [Info.][14]: PlaneScene: dst : (113,2)-(680,597)

ZOOM14:9 and ZOOM:
2007-04-18 19:57:20.250000 [Info.][14]: PlaneScene: crop T, B : 0, 0
2007-04-18 19:57:20.265625 [Info.][14]: PlaneScene: crop L, R : 0, 0
2007-04-18 19:57:20.265625 [Info.][14]: PlaneScene: video WxH : 768x576
2007-04-18 19:57:20.265625 [Info.][14]: PlaneScene: video AR : 768:576
2007-04-18 19:57:20.265625 [Info.][14]: PlaneScene: screen WxH : 763x595
2007-04-18 19:57:20.281250 [Info.][14]: PlaneScene: AR type : Zoom14to9
2007-04-18 19:57:20.281250 [Info.][14]: PlaneScene: PixelRatio : 1,3996
2007-04-18 19:57:20.281250 [Info.][14]: PlaneScene: src : (0,50)-(768,525)
2007-04-18 19:57:20.281250 [Info.][14]: PlaneScene: dst : (77,2)-(715,597)
2007-04-18 19:57:21.890625 [Info.][14]: PlaneScene: crop T, B : 0, 0
2007-04-18 19:57:21.906250 [Info.][14]: PlaneScene: crop L, R : 0, 0
2007-04-18 19:57:21.906250 [Info.][14]: PlaneScene: video WxH : 768x576
2007-04-18 19:57:21.906250 [Info.][14]: PlaneScene: video AR : 768:576
2007-04-18 19:57:21.921875 [Info.][14]: PlaneScene: screen WxH : 763x595
2007-04-18 19:57:21.921875 [Info.][14]: PlaneScene: AR type : Zoom
2007-04-18 19:57:21.921875 [Info.][14]: PlaneScene: PixelRatio : 1,3996
2007-04-18 19:57:21.921875 [Info.][14]: PlaneScene: src : (0,103)-(768,471)
2007-04-18 19:57:21.937500 [Info.][14]: PlaneScene: dst : (15,2)-(778,597)

It seems to me that the cutting values shown in the "src" are wrong calculated since they do not keep the 16:9 aspect ratio. For example, in the ZOOM mode the orignal image is vertically cut between 103 and 471 which yields an AR:
AR=768/(471-103)=2.0869... <> 1.77777...=16/9
the vertical band width should be: x=768*9/16=432, so the "src" box should be something similar to:

PlaneScene: src : (0,72)-(768,504)

The zoom14to9 admits a similar correction.

I think the source code badly calculates these figures. Please, I hope you can correct this!!!

 

[Noelix]

Same problem here - I never knew what the damn zoom modes were good for since all they did was stretch the image horizontally, and still not getting rid of the false letterboxing. I ended up finding a solution to this with the Autocropper plugin. Once you map the action->autozoom to a button on your remote it works great. Unfortunately I had to scour the forums to find that out.

 

[lkuech]

Well... the problem seems to be clear.
All zoom modes that have to calculate horizontal or vertical borders did not take the "global" pixel ratio into their calculations. Because of this only users with non squared pixels noticed this effect.
If you look at the values I have posted above you will see that with squared pixels ([Info.][5]: PlaneScene: PixelRatio : 1) the values fit pretty well.

A normal PAL 4:3 video is 768x576. A 16:9 crop out of it should have a vertical border of ~72. (576 - (2 * 72) = 432 ... 768 / 432 = 1,777_ = 16:9).

If you now take a look at the value fer2 has posted you will find a vertical border of 103
But if you divide this value by the PixelRatio set by fer2 you get 103 / 1,3996 = 73.5.

I have build a quick fix for all zoom mode using borders. Please test it deeply with all modes (Pan and Scan, Zoom, Zoom 14:9) and report it back here.

It is a modified core.dll compiled under the SVN of today.
Make a backup of your original file and replace it with this one.

I will delete this file sooner or later because of its size.
If these changes work, I will post these changes at sourceforge.

EDIT: Attachment removed because the change is part of the SVN's now.

Bye
Lars

 

[daniel_1980]

Replacing the core.dll causes MP not to start. I use stable release 0.2.2.0. I'm not into using svn etc., so I won't be able to test this in the near future.

 

[lkuech]

Yes. unfortunately this is a SVN file.

Bye
Lars