DVD (VOB) Frame Size

[Brosco]

Hi all, I am a hobbiest programmer and currently trying to learn Delphi.

I found a great free DLL that is a wrapper for DirectShow to make your own Media Player. Its at:
http://www.sagura.com/
(Note: I doubt that this DLL will work with any other programming language than Delphi - I tried it with Lazarus/FreePascal which is attempting to be Delphi compatible and it wouldn't work, so i doubt it will work for VB or C).

Anyways - with only a small program I was able to write a player for AVI, WMV, Mpeg, RM, VOB etc - and remember, I am just learning Delphi - so its a powerful DLL.

My one problem is when I try to play an unencrypted VOB its always reports that the frame size is 720x576, regardless of what the real size is. (Actually I have the same problem with Windows Media Player and most movies play with the width being 'squashed'). Anyone have any ideas? I have checked all the threads in this section and could not find a similar reference - so apologies if it has been answerred elsewhere.

Thanks in advance

Brosco

[jagabo]

I suspect all your VOB files are 720x576. But some should be displayed with a 4:3 aspect ratio and others with a 16:9 aspect ratio.

[Cornucopia]

You're in Australia, so for PAL 720x576 is correct and the most common(you should be able to have 704x576, 352x576 and 352x288 available to you as well, though, and the possibility for NTSC sizes).
There ought to be a (how do you say it in ProgrammerSpeak?)~port/pin/flag for aspect ratio (and maybe "TV system") as well as size. What other metadata "fields" does it report?

Scott

[SLK001]

The Sequence Header in the MPEG video gives the info you want. Just parse "00 00 01 B3" (in HEX, of course). The next 12 bits give you the HOR SIZE and next 12 bits after that give you the VER SIZE.

I'm not sure what the format of the data is (MSB or LSB first), but simple experimenting can give you that.

[Brosco]

Thank you all. Since this was my first attempt at playing with a DVD it never occurred to me that the mpeg width & height would be different to the aspect ratio required. I guess I better do some more searching on explanations of dvd formats.

But while I'm searching could you answer one more question? If my VOB is 720x576 and the aspect ration is 16/9 - should I therefore play it at 720x405? Or is that too simplistic and I'm missing something else?

Thanks again to all that responded.

[jagabo]

But while I'm searching could you answer one more question? If my VOB is 720x576 and the aspect ration is 16/9 - should I therefore play it at 720x405?

Yes. Or any other 16:9 frame size. My preference would be 1024x576 -- keep the height, stretch the width. And a 4:3 file should be resized to 768x576.

To be more correct, the 16:9 image is contained in the center 704x576 subsection of the 720x480 frame. But if you just ignore that and scale the entire frame you'll be close enough.

[Brosco]

Thanks again to for the help and very quick responses - it is truly appreciated.