Dumping Pioneer LaserActive MegaLD (Sega) and LDROM2 (NEC) LaserDisc Games

[Nemesis1207]

( Cross-posted from http://www.assemblergames.com/forums/showthread.php?38437-Dumping-Pioneer-LaserActive-MegaLD-(Sega)-and-LDROM2-(NEC)-LaserDisc-Games )

Hi everyone, I know few people know me here, but I do a lot of work furthering documentation and emulation, primarily for the Sega Mega Drive. Amoung a lot of other projects, I've been working steadily on a process to dump MegaLD disks for the Pioneer LaserActive over the last few years. The Pioneer LaserActive is a Laserdisc player, which supported "add-on" modules, one of which was the PAC-S1/PAC-S10, which gave the ability to play Mega Drive/Mega CD games through the system, and another one which was the PAC-N1/PAC-N10, which gave the ability to play TurboGrafx games. Both of these units added the ability to play unique games designed for these systems however, which stored digital data on special Laserdiscs for the game code and data, along side analog video and audio, which was combined with the graphics and sound output from the add-on modules.

Due to the unique storage method used for these games, the data for these games has never successfully been dumped before. I own a LaserActive, and I've been working on solving this issue by reverse-engineering enough of the hardware to write a custom program, which can give me control of the unit and allow me to dump the raw digital data and analog video/audio streams. Just recently, I've got a dumping process fully working. I've just posted a dump of the digital game data for the US release of "Space Berserker", with rips of the video tracks to follow soon. You can see the following post on SpritesMind if you're interested in knowing more:
http://gendev.spritesmind.net/forum/viewtopic.php?p=15003#15003
http://nemesis.hacking-cult.org/MegaDrive/MegaLD/Space%20Berserker/Space%20Berserker.png
This same dumping process should also work for LDROM2 games, IE, I should be able to dump an LDROM2 game using the PAC-S1/S10 module and the same custom program I've written.


I'm posting this here, because nobody has ever dumped MegaLD disks before. With this first dump now online, work on emulation can begin, but there's another important task that needs to begin too, which is dumping the LaserDisc contents themselves, so we can preserve these games for the future. I have all the required hardware to rip both the digital and analog data from these disks, however, the only game I own is Space Berserker. I've had a few collectors contact me already with interest in getting the games they own dumped, and I'm now at the point where I'm ready to accept loans of MegaLD and LDROM2 disks for the purpose of ripping them. I'm interested in all disks, from all regions. Feel free to either post in this thread or PM me if this is something you'd be interested in. Even if you're a bit wary sending your disks to me, if any LaserActive owners could list in this thread what disks they own, it would be good to know who has what. I suspect the most common disks will be dumped soon enough from one person or another, but some of the rarer titles might only be in the hands of one or two people who are going to see this, so it'd be good to know who has what.

I'm not going anywhere anytime soon, so there's no rush with this. I can dump disks over the next few months, or the next few years, depending on how quickly this moves. Let me know if you're able and interested in helping out with this project.

[JSoup]

Similar project: http://www.digitpress.com/forum/showthread.php?160157-LaserActive-Preservation-Project-Interesting-Stuff

[Nemesis1207]

Heh, that's funny timing :). I'll send them a message, see if we can combine our efforts. Dumping the video data isn't enough, we really need to get the digital data off these things.

[Kiddo]

Heh, that's funny timing :). I'll send them a message, see if we can combine our efforts. Dumping the video data isn't enough, we really need to get the digital data off these things.

Wow, the prospects of these efforts sound exciting! I hope you're able to grab Road Prosecutor and Triad Stone.

[markusman64ds]

And I thought the only way to dump the games was to ask the original developers for their old computers, and get the data from that.

[Kiddo]

And I thought the only way to dump the games was to ask the original developers for their old computers, and get the data from that.

Nah, I always believed that if LD Arcade games could be dumped, the LaserActive stuff would probably be about on par to dump in terms of difficulty. Of course, this is coming from someone who doesn't really know anything about dumping Laserdisc games.

[xelement5x]

This is very very cool. I've got a solid collection of titles but nothing very rare unless you consider Triad Stone a rare game. I'd also recommend adding a thread at PCEngineFX as I know a fair number of people there that have many of the games.

From what I read though, it sounds like you only have part of the information dumped, just the data for gameplay and not the video/audio sections yet? Also, I'm not sure if there's even anything to play them, since from what I understand the PAC works in conjunction with the LaserActive unit to decode and play the video and game.

[Nemesis1207]

From what I read though, it sounds like you only have part of the information dumped, just the data for gameplay and not the video/audio sections yet?
I have a process to dump the video/audio tracks, and I have a very high-end capture card which can get superb quality from the capture process. I've dumped all the video tracks from Space Berserker, I'm mostly just fiddling around with how to encode it, what codecs to use, etc. The "lossless" video capture (by "lossless", I mean, no quality lost after the capture process) I have currently for Space Berserker is on the order of 7GB for 30 minutes of video. I'll be releasing a smaller re-encoded version (probably along with the lossless version) which is intended for direct use in emulation. I do still need to do some tests to guarantee I've got the frames synchronized, so that when it comes to emulating these games, we know that the time codes on the disk match perfectly with the time codes on the ripped video. I'm also going do be doing a fairly complex "multi-sample" process, where I rip the video tracks half a dozen times over, and use a weighted average sampling method to eliminate analog noise artifacts and the like from the ripped video. I've talked a bit about it on SpritesMind. I want to get the ripping procecss "right", and just do it once, rather than have to rip all these video tracks again in the future because I made a mistake. When I feel confident I've got the ripped video correct and synchronized, I'll be posting it online.


Also, I'm not sure if there's even anything to play them, since from what I understand the PAC works in conjunction with the LaserActive unit to decode and play the video and game.
There isn't anything capable of playing them yet, but I also do a lot of work in reverse engineering hardware in order to document and emulate it. The PAC-S10 is completely hardware-compatible with the Sega MegaCD/SegaCD. When you boot a MegaCD game, it actually loads the same MegaCD sub-cpu bios that you'll find in many MegaCD units, so the hardware is completely compatible. The only difference with the PAC-S1/PAC-S10 over a normal MegaCD is that there's an extra controller chip on the bus mapped in at a previously unused memory address, which provides the extra interface to the LaserActive hardware necessary in order to control the Laserdisc-related hardware options. All we really need to do in order to emulate Mega-LD games is reverse-engineer the interface to this chip. The PAC-S10 bios is what communicates with the hardware, but it itself has an interface which is different, that needs to be reverse-engineered in order to figure out what commands it's sending to the hardware. Now that we have a game dumped, we can more quickly decypher the bios calls, which will in tern help us to decypher, and eventually emulate, the hardware interface, which can then be added to an existing MegaCD emulator, and you'll have a working MegaLD emulator too. I've done some work in reverse-engineering the bios functions, and a little bit of work in reverse-engineering the hardware interface too. That process will continue for awhile yet, but now that we have a game dumped, the task of emulating the system can really begin. The only reason this system hasn't been emulated yet is because we haven't had any "sample data", IE, the games, as a starting point to work with.

[Nemesis1207]

I'm bumping this thread to say I'm now reviving this project and accepting loans of disks. Head over to this thread to see current progress or to loan disks for dumping: http://gendev.spritesmind.net/forum/viewtopic.php?t=1647