I never know if I actually understand what all of you are talking about... but just in case I do :P

Is there any chance that this project could be helpful? http://gendev.spritesmind.net/forum/viewtopic.php?f=17&t=1647

It appears that using the Pioneer LaserActive system with the PC1 PAC gives you direct access to the iso sectors on the disc. Something like http://www.kryoflux.com/?page=download might be able to capture this directly.

Maybe that signal could then be fed to LD-Decode? Not sure if that would give any better results than a graphics card solution.