How to burn ISO images with PgcEdit
ensuring 32k gaps between IFOs and BUPs


There can be gaps on a DVD.  The most notable ones are those used to ensure that no ECC block contains any portion of an IFO file and its associated BUP file.  Since ECC blocks are 16 sectors long (32K), the easiest way to accomplish this is to ensure that there are 16 sectors between the end of the IFO and the start of the BUP.  With VIDEO_TS.VOB or VTS_xx_0.VOB files less that 32K (or absent) this means using a gap.


Burning programs handle this in one of three ways, two of which are correct.

         They can honour the authoring program's layout and place the data on the disk according to the pointers in the IFO files.

         They can make their own layout decisions and alter the pointers accordingly.

         They (notably Nero, at least in several past versions) pack the data as closely as possible and ignore the pointers. J J

The upshot of this is, to use ISO images to maximize the chance of a "good burn".  Burners and burning programs don't examine the data or the layout of an ISO image, they just burn it.

Why is this needed?

If an IFO is unreadable (e.g. a CRC error in a sector), the player looks for the BUP, which is stored on the disk right after the VOBs for the titleset.  Now suppose the VOBs for that titleset are small and the data is packed in.  There is a chance that the BUP occupies exactly the same bad block that the IFO did, making the BUP useless and the disk, dead in the water.

Essentially, the basic problem is that without the proper spacing, a single CRC error that would normally only affect one of the two files will affect both, rendering both useless.  If proper spacing exists, it would take at least two CRC errors (one affecting each) to render both the IFO and BUP useless.

It’s important that one failed sector does not ruin both the IFO and the BUP, making the DVD into yet another coaster.

This problem does not affect disks which have VOBs for each and every titleset totalling 32K or more.  However, crucially, it does affect ALL disks “reauthored” by DVD Shrink and Nero Recode (and possibly other one-click backup programs).

The solution!!!

PgcEdit has just (Jan 17 2005) released version 0.4.8, which, in conjunction with DVD Decrypter and ImgTools Classic, can burn ISO images with 32k gaps.

Let’s start with an example:

Suppose you had a DVD that looked like this (actually, the files are stored on the disk in the order IFO – VOB(s) – BUP):

VIDEO_TS.IFO                                 20k
VIDEO_TS.BUP                               20k
VIDEO_TS.VOB                               10k (you may have blanked this with a popular blanking program such as PgcEdit or VobBlanker)
VTS_01_0.IFO                                 86K
VTS_01_0.BUP                                86K
VTS_01_0.VOB                         38,000K
VTS_01_1.VOB                     1,048,574K
VTS_01_2.VOB                     1,048,574K
VTS_01_3.VOB                     1,048,574K
VTS_01_4.VOB                     1,048,574K
VTS_01_5.VOB                       200,000K (this titleset is obviously the main movie)
VTS_02_0.IFO                                 12K
VTS_02_0.BUP                                12K
VTS_02_1.VOB                               20K (this might be the original – just a second of blackness or you might have inserted a "still image")
VTS_03_0.IFO                                 60K
VTS_03_0.BUP                                60K
VTS_03_0.VOB                              500K
VTS_03_1.VOB                       140,000K (these are obviously some extras)


Now, if you have followed the dialogue above, you will know that problems can be caused if there isn’t 32K between the end of the IFO and the beginning of the BUP (remember, the files are stored in the order of IFO – VOB(s) – BUP).

This isn’t a problem for VTS_01 and VTS_03, but VIDEO_TS and VTS_02 are in trouble.

Here’s what to do.

First, what you need:

        PgcEdit v0.4.8 or greater – Get it at

        ImgTools Classic v0.91.4 – Get it at

Now, on to the technique – it takes about 5 minutes.

1.         Open PgcEdit v0.4.8 or higher and open the project by browsing to the folder containing your DVD files.

2.         Make sure the option “When saving, leave at least 32K of space between IFO and BUP” is ticked.


3.         Save the project (press Ctrl-S)

4.         To burn your DVD, click on File – Burn DVD / Create ISO

5.         There is a one-time setup of your file locations and burner drive letter.

Pressing save will bring up the main burn screen.  If your files are not already in the VIDEO_TS folder, PgcEdit will offer to put them there and create the file structure automatically for you. This minimises the chance of a bad burn because of lack of these folders.

Notice also the handy information dialogue at the top of the screen!

Tick the appropriate boxes (I always use verify unless I’m doing a test with an RW).

Give the output ISO file a name – anything will do so long as it ends in .iso and pick a convenient location to save it.  The easy way is just to click on the 3 dots to the right and you can generate the ISO where you like (I use the desktop).

Tip: If you have 2 hard drives, saving the ISO (which is temporary and will be deleted pretty soon) on the other IDE channel will speed up its creation a lot.

Now, fill in the volume name (this is the name of the movie – e.g. GANGS_OF_NEW_YORK).  Don’t forget those underlines and make sure they are all UPPER CASE.  (If you have filled in the name of the disk under DVD-Text General Name, this will be displayed automatically. Very handy)

Press OK.

6.         The ISO creation starts (it will take about 4 minutes), leaving perfect gaps between the end of the IFOs that need them and the start of the corresponding BUPs.  Once finished, PgcEdit will display the following screen:

Notice the “pad” was 16 for VIDEO_TS.IFO. This is because either there was no VIDEO_TS.VOB or it was a 0 byte file.

In any event, now there are 16 sectors (=32k) between the end of the IFO and the beginning of the BUP. J

The message that the ISO was created OK means you’re good to go and PgcEdit will launch DVD Decrypter to burn (and verify if you have selected that option – always a good idea, IMHO).  If there was an error creating the ISO, the process will stop and you will NOT make a coaster.

Questions should be directed to the doom9 forum here.

Happy and safer burning with PgcEdit!