Why do some DVD+R DL Images need Padding?

[dbminter]

I created a DVD Video image with a VIDEO_TS that was just under a DVD-5 but I added some folders and files to the root directory that made it about 5.5 GB total.  The image file created was 8 GB.  I know this extra 2.5 GB is Padding, but I was wondering what this Padding is.  Why is it necessary?

[LIGHTNING UK!]

Were you prompted to pick a layer break position?

[dbminter]

I was, though I'm not entirely sure why.  I think the VIDEO_TS was small enough to fit on one layer.  So, I don't know why it wasn't on Layer 0 and the 800 MB of files and folders wasn't on Layer 1.

 

 

So, setting a layer break triggers the creation of padding?  How much padding is chosen/how is this determined?

[LIGHTNING UK!]

It adds as much padding as is required by the LB position you select.

 

It defaults to putting DVD video data before other data, so I can only assume it didn't all fit on the first layer and that's why you had to pick a LB position.

[dbminter]

Does the padding fill up the remaining space so Layer 1 is filled to capacity?  If so, why?

 

 

Which of the 2 layers is the smaller one?  0 or 1?  If 0 is the smaller layer, then that may be why the VIDEO_TS didn't fit in Layer 0.  It fit on a DVD-5, but I know that a DVD-9 is not, as the name implies, exactly twice the size of a DVD-5.

[LIGHTNING UK!]

The padding comes before any data. It's there to shift the data along so the LB you've chosen is physically possible - as L0 must be >= L1 in size.

 

It would be easier to explain if you could get a screenshot of the LB selection box (if you still have the source folders handy) and post the log from the burn