Aspect ratio video problem

[sub]

They're probably part of the picture. Many channels have a small area of black at the left and right of the picture, which is normally off the side of your screen when watching normal TV. Unfortunately there is no zoom with VMR9 Custom that will help this.

[ShiningDragon]

They're probably part of the picture. Many channels have a small area of black at the left and right of the picture, which is normally off the side of your screen when watching normal TV. Unfortunately there is no zoom with VMR9 Custom that will help this.

Mhm, but i don't have them with normal VMR9. The PC is connected VIA VGA to LCD. Or did you mean, that something else cuts the border from the picture under VMR9?

[_gl]

Shi, can you take some screenshots? It will make it clearer what the problem is.

[ShiningDragon]

Shi, can you take some screenshots? It will make it clearer what the problem is.

Of course, here you are. It's not only that there are black bars added, even the width of the screen seems to be bigger.

As Example: Normal i have 768 x 576, if i am using VMR9 Custom than i have something like 798 x 576, like it looks.
First time i stumble on it while skinning the Mainmenu. With VMR9 the Pictures fits PERFECT into the Panel. With VMR9 Custom i had added these annoying black bars left and right.

[_gl]

Interesting, the vertical matches. I'm on a GF6200, but I use PAL 720 x 576 with 91.03 beta, and sub's custom renderer patch works OK on 4:3 and 16:9 (all I use).

Isn't 720 the correct width for PAL? For mpeg2 at least. Maybe Sub didn't test 768.

[Kyle]

I had the same problem. I was able to tweak the "Fill" Aspect ratio setting to fill the screen. I then modified the other aspect ratios to take the "true" screen size into account. Of course, there is nothing you can do with the Auto aspect setting.

Kyle

[ShiningDragon]

Interesting, the vertical matches. I'm on a GF6200, but I use PAL 720 x 576 91.03 beta, and sub's custom renderer patch works OK on 4:3 and 16:9 (all I use).

Isn't 720 the correct width for PAL? For mpeg2 at least. Maybe Sub didn't test 768.

Nope, real PAL Resolution is 768 x 576 @ 50 Hz. In the Digital World the Resolution 720 x 576 got standard though. But you can calculate yourself: 576/3 = 192*4 = 768! Only 768 x 576 is a true 4:3 Aspect Ratio. If you have 720 x 576, then you have, truly spoken, something undefined ^^;

The Problem isn't only the Panel. I could live with the Inset and play around at skinning. But if i display the LiveTV to my LCD (1280 x 720, 16:9) then i have the same borders left and right on screen. It's not possible to stretch the picture so it fits perfect within the LCD. This can be done only with VMR9 only, but subs solution with Aspect Ratio is wunderful @ VMR9 Custom Renderer.

For now i have only two options: Use VMR9 WITHOUT any Aspect Ratio (i'll get EVERY TIME Black Borders on Top and Bottom on the LCD, even @ 16:9 Material -> no aspect ratio, OR i am using VMR9 Custom Renderer and have to live with the black borders on the left and right side.

And thus i am not a programmer, i can't see the error. The PVR is configured to capture @ 768 x 576/50 Hz.

I am only wondering, where's the weakpoint.

[_gl]

Nope, real PAL Resolution is 768 x 576 @ 50 Hz. In the Digital World the Resolution 720 x 576 got standard though. But you can calculate yourself: 576/3 = 192*4 = 768! Only 768 x 576 is a true 4:3 Aspect Ratio. If you have 720 x 576, then you have, truly spoken, something undefined ^^;

I see. Anyway, try 720 to see if that fixes the problem. Sub is doing custom rendering using Direct3D AFAIK, it's possible this is a texture size issue that he didn't test for.

[csy]

Nope, real PAL Resolution is 768 x 576 @ 50 Hz. In the Digital World the Resolution 720 x 576 got standard though. But you can calculate yourself: 576/3 = 192*4 = 768! Only 768 x 576 is a true 4:3 Aspect Ratio. If you have 720 x 576, then you have, truly spoken, something undefined ^^;

No, unfortunately you are not correct.

Analogue and digital video use rectangular pixels, meaning true video display devices like TV's alter the aspect ratio when the image is displayed on the screen. Computer graphics displays (standard computer monitor) use square pixels and are not engineered to display video correctly.

http://www.mir.com/DMG/aspect.html

The correct calculation is:

width/height = DAR/SAR

where DAR (Display aspect Ratio) describes the physically displayed image
and SAR (Sample Aspect ratio) describes the display pixel shape

PAL 4x3 analogue TV's have SAR=59:54
PAL 16x9 analogue TV's have SAR=118:81
As you can see the widescreen TV horizontally-stretches the image which is why 16x9 and 4x3 both use the same 720x576 pixel resolution

Also, when the analogue scan lines are sampled, they are actually fit into just over 702 (standardised 704) of the total 720 horizontal pixel resolution.

So applying the calculation:

Width
= [DAR/SAR]*height
= [(4/3)/(59/54)]*576
= 702.9 pixels

So in conclusion the REAL digital video PAL resolution is 704x576 fitted inside 720x576 container.

The displaying device must obviously crop the 720x576 left and right by 8 pixels to restore the correct aspect ratio.

My Nvidia 6600GT TV-out worked correctly and only displayed 704x576 resolution on its TV-out signal. However my ATI 9550 TV-out is wrong and displays 720x576 resolution on its TV-out, however the black bars are hidden within the overscan of the TV.

The discussion so far is all based on direct 1:1 pixel mapping of the source resolution directly to the screen resolution.

Now the theory all falls apart if you have a display with square pixels because they are not designed to display digital video correctly. So instead you must scale the image to the correct dispaly aspect ratio using "aspect ratio correction". This is well and good, but you have to know if the aspect ratio correction is based on rectangular pixels or square pixels and where it is applied. Most software video decoders have inbuilt aspect ratio correction which alters the source resolution, which is then subjected to rendering image adjustments (GBPVR config.xml adjustments) and finally the display pixel SAR.

GBPVR "auto" aspect ratio is very clever and works well, but will be based on standardised resolutions.

ShiningDragon - you are having difficulties because you have chosen not to use 720x576 resolution.

[ShiningDragon]

@csy

Thank your for this precise description. So than is this like the Pixel Ratios on DVD Covers 2,3333:1, 1,85:1 and so on? This has something to do with the resolution?

Mhm, looks like i really have to resize my Pixel and were wrong. Basically i thought, because analogue TV has a 4:3 Resolution and 576 vertical Lines, that the horizontal ones should be 768 Pixel. I never thought of rectangular Pixels on TV!

So i'll try a few modes. As Testscreen i could make some circles to find out the correct resolution and aspect ratio, i think.

Thanks for the worthy hint =)