A Sega fan and collector since his youth and an emulator hobbyist since the early ’00s, Nemesis tracked down his first LaserActive unit for $200 in 2004. By 2009, he was publicly musing about what might be needed to finally get emulation support working for the short-lived system. “I really don’t think it would be very hard to do,” Nemesis wrote in a forum thread at the time, in what would end up being a hilariously large understatement.
While monitoring memory registers and reverse-engineering the actual system logic of the LaserActive was relatively straightforward, getting the necessary game and video data from the Mega-LD discs was a massive undertaking. Nemesis explained that the only way to get at the crucial “table of contents” data (needed to make sense of everything else on the Mega-LD disc) was “solder[ing] a bunch of physical tapping wires into my Sega PAC-S10 module, and us[ing] a Saleae logic analyzer clone to do a streaming capture of the data lines.”
Then there was the problem of capturing the massive amounts of analog video on a LaserActive disc in a lossless format suitable for emulation. Commercial analog capture cards that worked for standard LaserDisc movies proved unequal to the task, since they usually ignored the VBI control data that was hidden beyond the borders of the 480i CRT displays of the time. The lossy capture cards also often had trouble correctly interpreting the multiple streams of overlapping video data that could be arranged in nonstandard ways on a LaserActive disc.
A circa 2019 shot of the worktable that Nemesis used for his LaserActive ripping efforts.
Credit:
Read Only Memo / Nemesis
“Rarely is the [LaserActive] player just playing back a video normally,” Nemesis explained to Read Only Memo. “Games will often have completely different video footage per field, with only one shown, or skip over every second frame, to mix four or more video streams in the same area of the disc. Many games use this for seamless ‘branching’ such as whether you go left or right, and this can change constantly and seamlessly during playback.”
