Help on Video Atriibutes

[SoundScape]

Hi,

I edited and burned 2 DVDs which have 16:9 menus. When tested them in PowerDVD, menus were displayed as 16:9 but using my standalone and my 4:3 TV, I noticed that the menus were being displayed full screen, i.e. 4:3. Notice that I have set up my DVD player to display as 4:3 Letterbox. When I opened the menu of one of these DVDs in PgcEdit and clicked on "Domain Stream Attributes", I noticed that the menu video was as 16:9 Automatic Pan & Scan. Is this the reason why it is displayed full screen? If I change it to 16:9 Automatic Letterbox, will it be displayed as 16:9 (with top and bottom black borders) on my TV?

In general, what should the video attributes set to for a 16:9 video in order to be displayed correctly on both conventional and 16:9 TVs? And one more question...:D If a 16:9 video that is already letterboxed is set as Automatic Letterbox, will additional top and bottom borders be added to it? Will this result in a squeezed picture when played in a widescreen television?

Thanks in advance for any help on the above, I hope you understood what I wanted to say :p

[mpucoder]

Originally posted by SoundScape
I noticed that the menu video was as 16:9 Automatic Pan & Scan. Is this the reason why it is displayed full screen?
Yes
If I change it to 16:9 Automatic Letterbox, will it be displayed as 16:9 (with top and bottom black borders) on my TV?
Yes, but you will have no buttons or highlights. The main purpose of these 2 bits is to let the player know what modes contain the information to make a menu.

In general, what should the video attributes set to for a 16:9 video in order to be displayed correctly on both conventional and 16:9 TVs?
16:9 video will always display as widescreen if the player is aware that the display is widescreen capable. The attribute bits only affect the display of 16:9 on a 4:3 display. What is correct is what the author of the DVD added for 4:3 display highlights and buttons.

And one more question...:D If a 16:9 video that is already letterboxed is set as Automatic Letterbox, will additional top and bottom borders be added to it? Will this result in a squeezed picture when played in a widescreen television?
A 16:9 video cannot be already letterboxed. Video that is already cropped is 4:3 video. This attribute bit allows the player to expand the picture for a widescreen display. And, since it only works with 4:3 video, and the auto-LB and auto-PS only work with 16:9 using both is non-spec.

[SoundScape]

mpucoder,

Thanks for the detailed explanation. I will change the flag to "Automatic Letterbox" for the menu video and see what happens with the buttons (when played in my 4:3 TV, of course). Not that I don't trust what you said, I just need to see for myself :D

You said that a 16:9 video can't be letterboxed. I opened a 16:9 VOB in DGIndex and in the preview black borders were visible in the video. Doesn't that means that the video is letterboxed?

Thanks in advance!

[mpucoder]

Originally posted by SoundScape
You said that a 16:9 video can't be letterboxed. I opened a 16:9 VOB in DGIndex and in the preview black borders were visible in the video. Doesn't that means that the video is letterboxed?
That's not quite the same thing, although it is cropping, it's to accomodate aspect ratios wider than 16:9 (1.77:1), such as 2.35:1.

The "source letterboxed" flag applies only to 4:3 video and tells the player how to display 4:3 video on a 16:9 display. If the video is 16:9 the flag is ignored.

The auto-letterbox and auto-panscan flags apply only to 16:9 video and tell the player how it may display 16:9 video on a 4:3 display. If the video is 4:3 both flags should be set to disabled, but they are ignored.

[r0lZ]

No, the presence of black borders doesn't mean that the video is letterboxed. For example, a Cinemascope movie must have black borders to allow it to be displayed correctly even in 16:9. This is because the display aspect ratio of Cinemascope is larger than 16:9.

[SoundScape]

mpucoder,

I tested my DVD with "Automatic Letterbox" this time and guess what? You were right, although menu buttons are visible, highlights are displayed lower than the buttons :(

Why is this happening? I mean, since the menu was authored as 16:9, shouldn't it display properly, i.e. buttons and highlights visible, on a 4:3 TV? Is there any way I can make the menu display as 16:9 without totally messing it up? Sorry if you have answered this in your previous posts but there are so many things I don't understand about video. I hope I will with your help :D

One more thing: If I uncheck both Automatic Letterbox & Pan&Scan and leave the video as 16:9 will that fix the problem? Thanks for your patience and again my apologies for asking so many questions. I believe you were like me once...no offence implied ;)

[mpucoder]

Each display mode has its own subpicture and highlight information because only the video is resized, the subpicture and highlight use screen coordinates. This allows subtitles to be placed below a letterboxed movie, in the black band. If the subpictures were mixed with the video before resizing you couldn't do that.

Disabling both auto-lb and auto-ps is not allowed (OK, IfoEdit will do it, but it shouldn't). 16:9 video MUST have one of the auto modes enabled so that it can be displayed on a 4:3 display.

All DVD players I've seen have a setup option to tell the player what kind of display is connected. If this is set to "widescreen" or "16:9" then the widescreen version of the menu/movie will be shown. If not the DVD player is defective.

[r0lZ]

When a 16:9 video is displayed on a 4:3 TV, the player must resize the image (and, for letterbox mode, add the black borders) so that an old 4:3 TV will receive a standard image.
The video is resized, but NOT the subpics (subtitles and menu button highlights.) Instead, several subpics streams are multiplexed with the video: one for each possible display mode (real 16:9, letterboxed or pan&scan.)
So, if you change the display mode, you must also use another subpic stream if you want to display them properly.

The two flags Automatic Letterbox and Pan&Scan in the domain streams attributes are used to inform the player of the valid display modes (ie, the display modes for which there are specific subpic streams.)

In each PGC, the subpic assignments (or subpic status) tells the player which stream must be used in each mode. There are four numbers in the status, but the numbers for the unsupported display modes are ignored, and are therefore normally left to 0 (the first subpic stream.)

So, if you want to change the display mode flags in the domain streams attributes, you must also change the subpic status in each PGC of the domain, to use the right stream in letterbox mode. Unfortunately, as your original DVD was authored for Pal&Scan only, it does probably not include the right stream for Letterbox mode.

In the case of subtitles, it is sometime possible to use another stream. It will not be correctly placed, but it will be visible.
In the other hand, menu buttons highlights must be placed exactly at the right place. So, you will not be able to change the display mode of the video without reauthoring the whole menu, and designing new highlights, or resizing the original ones.

[Sorry, mpucoder. You answered while I was typing...]

[mpucoder]

Originally posted by r0lZ
[Sorry, mpucoder. You answered while I was typing...] But you added some very useful information.

[SoundScape]

Thanks to both of you guys, you've been more than helpful. I fully understood how the whole thing works :D

I'll leave the menu to 16:9 Automatic Pan&Scan since I don't have the knowledge or time to re-author the whole menu! I should probably buy myself a new widescreen TV too...;)

Again, many thanks!