Why do I have to extract PGC to frameserve it?

[kurbads]

Isn't frameserving about eliminating unnecessary disk consuming operations?
Why isn't it possible to work with framserving applications on PGC basis?
Please, don't give me smart answers like: "noone needs it"!
I just realized DVDRebuilder can suply information for it!

[manono]

I just realized DVDRebuilder can suply information for it!

And DVD-Rebuilder make a D2V project file for frameserving via AviSynth. It works on a cell-by-cell basis. I'm not sure I understand the question.

Why do I have to extract PGC to frameserve it?

How else are you going to frameserve? By Vob? Not likely.

[kurbads]

Video Title Set can be framserved with DGIndex.
DVD Rebuilder creates aviscripts pointing to the frames belonging to each cell in the Title Set e.g.:
...
trim(13113,14107)
...
trim(14108,46603)
...
Apparently PGCs also have their starting and ending positions.
Unfortunately it is impossible to determine them.
The only choice is to extract the whole PGC even if you already have decripted files on hard disk and then DGIndex it.
It is not a problem since the disk space and speed has grown immensly in recent years.
But I just do not like the idea.