Total DVD 6.17Gb, Total DVD filesize 4.48Gb?

[setarip_old]

To r0lZ, jsoto, mpucoder, LIGHTNING UK! and other experienced programmers:

(posted in this sub-forum because this is where you folks "hang out" ;>})

I recently purchased the Region 1 version of "Duma", a Warner Bros. release. Windows Explorer indicates that the DVD contains 6.17Gb used. However, the total combined filesize of the contents ("VIDEO_TS" and "JACKET_P". There are no "PC only" files or folders) of the DVD is only 4.48Gb.

I can think of only two reasons for the huge disparity:

1) There's a whole bunch of other "stuff"/data on the DVD that's not accessible via DVD navigation or Windows or,

2) There are dummy entries intentionally made in the file allocation table to pad the apparent DVD size.

My question to you knowledgable programmers is, if there is, in fact, additional data on this DVD, how can I determine where on the DVD it is located and how can I access it?

Thanks

[r0lZ]

Hum, might be another kind of protection.
Normally, on a PC, the ISO filesystem is used to access the files, and on a standalone, the UDF filesystem is used. I've read somewhere that the ISO filesystem might be modified by some protections to fool the rippers. I'm not sure those DVDs are playable on a computer. On some of them, it is even impossible to see any file.

To compare the ISO and UDF filesystems, you can use ISOBuster. It's not a free program, but you can use the non-registered version to inspect the filesystems.
Compare the LBA and sizes of the files. They should be identical.

I don't know if your second suggestion is possible. Honestly, I'm not a specialist of this kind of stuff. Anyway, if some sectors are referenced but not accessible via the filesystems, I doubt that those sectors contain meaningful data.

Have you tried to rip the DVD? Is it problematic?

[setarip_old]

might be another kind of protectionThat doesn't seem to be the case. I should have mentioned that my rip of the DVD plays perfectly and completely, from start to finish, including "extras"...

[blutach]

Any hidden folders where they have put some junk?

Regards

[setarip_old]

Any hidden folders where they have put some junk?Noooooo...

[blutach]

So what does ISOBuster say?

Regards

[setarip_old]

To r0lZ, jsoto, mpucoder, LIGHTNING UK! and other experienced programmers:

I've resolved this curious situation. I loaded the DVD into DVD Decrypter v.3.5.4, set to "Read .ISO". It indicated a total disc size of 6.17Gb, and the first file it recognized was "VIDEO_TS.IFO", starting at LBA 888154.

After ripping the .ISO to my hard drive, I used a hex editor to examine all of the sectors up to that point. They are all filled with zeroes!

Although this explains the reason for the disparity between total DVD size and the combined filesize, I guess the mystery will remain as to why this was done. It's not any kind of protection...

[r0lZ]

Since it's a DL-DVD, this gap might have been created to align the LB cell with an ECC block, and to have enough data on L0. This method is widely used, and is similar to PgcEdit's method (though PgcEdit puts the gap before VIDEO_TS.BUP, not before VIDEO_TS.IFO.)

[setarip_old]

Since it's a DL-DVD, this gap might have been created to align the LB cell with an ECC block, and to have enough data on L0.You're probably correct, since the actual data is barely larger than a DVD-5 (Total combined filesize is only 4.8Gb).

Thanks for solving the second part of the mystery ;>}

[blutach]

Thanks for the info setarip.

Regards