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

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.

 

Very cool! I've always wanted to try out a LaserActive. Never knew they had LDROM. Ha.
Also this prompted me to go out and buy a Laserdisc player.

 

I've been contemplating doing this for some time but I lack the knowledge and equipment to begin. I do, however, own Pyramid Patrol.

 

I don't have space for a laserdisc player now. But last time I bought one local, it was unsurprisingly defective. Standard used item risk.

I guess I should either get another one or sell my Urusei Yatsura discs. They aren't likely to be much different from the DVDs.

 

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

 

Then I strongly suggest uploading the program used to dump LD-ROMs because preservation takes priority over personal issues.

 

Exactly.
I respect your feelings, but it would be unacceptable to put your personal feelings above the common interest.
What makes me worried is that I already offered help, being able to do a proper work (read it both as "good work" and "better work" than what I saw) but never got an answer, so I guess it is a "keep it all for me" scheme...

 

You guys are my heroes ! (Nemesis, TascoDLX, ChilliWilly and all the other helpful people at spritesmind)

Now this makes me feel like getting a real LaserActive....

 

I've got a spare but you'd have to be interested in figuring out why LD movies don't output video and why LD-ROM games have corrupted sprites as well as no background video. It sure wasn't the Sega-PAC.

 

We can talk about that in private... Anyway I love the challenge of putting broken things together again.

 

If the discs are dumped properly could they be converted into CD format?

The laseractive has a single laser and CDs are able to hold analogue data and digital data. So I don't see why it won't be possible to reproduce the games on CD.

The only LD Game I own is Hyperion and it's the demo version of it.

 

By what I understood of this, for emulation purposes we will end with two files, one being the actual "ISO" data which contains the game program and the VIDEO data, encoded on some format which will then be used by the emulator as background for the game sprites and video to be overlaid on top of.

I honestly don't think there's any possibility of this result on "copies" of LD games that would be playable on the real hardware.

 

Shoot me a PM at your leisure. I will need to find out how these were packed originally so that the tray mechanism doesn't get destroyed; as for the specifics on the damage all I know for sure is that someone recapped an entire PCB inside at some point; some traces are damaged and have been repaired. I don't believe that is the reason for the issues, however.

I'm not fully aware of how the original composite video signal was generated but obviously there is some difficultly producing new LD-R media this long after the full discontinuation of the hardware. I think we should be grateful preservation is at least possible.

 

This isn't about personal issues or feelings, it's about my personal moral standards, which I place much higher than this project. That's the final word on this issue for me, I won't let these disks in my house, period. I'm not stopping anyone else from ripping them though, and I will be releasing my method and dumping program, once it's ready for that.

You're taking this all wrong. I know you posted offering help ages back. By that point, I'd already shelved this project for the time. I'm balancing leading a big project at work, raising two kids, developing my emulator Exodus, and over this last year, caring for a wife who's had health issues. I put this project on the back-burner, and I'm just picking it up again now. I was actually going to contact you and discuss what you said further, I just haven't had a chance yet. I often only get to check forums on my phone right now between doing other things, and it's hard to write a proper message on a phone.

I have no intention of hoarding or controlling anything. In the thread I referenced one of the first things I mentioned is that I'm going to release all the dumps publicly, and I'm going to release a dumping program once it's ready. Right now, it's not. As I said, it's very manual right now. I'm literally toggling bytes on-screen using a visual register editor for the LaserActive hardware interface to send commands to the unit. I'm bypassing the bios and going straight to the (completely undocumented) low-level interface to control the drive, since it's the only way I can get the accuracy and control I need. Some of the most critical hardware information I've gathered on the unit has only been done in the last few days, and I still don't have enough to make the dumping process as simple as it'll need to be to be workable for other people who don't know what input register 0x19 does. For example, my current method to determine if a disk contains digital data at a given sector is to attempt to read digital data from it, at which point, if no data exists, the system locks up, and I need to do a hard reset. The TOC information does NOT indicate what areas contain digital data, it's simply the TOC for the Laserdisc video tracks. This makes the digital dumping process very manual and awkward right now. I'm searching for a better data read method, but I need to see a few more disks before I can be certain I'm using a method that will work for all disks.

The video capture process is also complicated. A simple video rip is useless unless each field is separated, or the interlaced stream is completely lossless, since the LaserActive hardware allows two totally different video streams to be encoded into the odd and even fields of a frame, and the video playback can be restricted to an individual field. That can be done with the right hardware, but the part that's not quite as simple is that in order to correctly sync that video, you need to correlate a specific field of your ripped video stream back to the time codes and ring numbers reported by the hardware. That requires manual stepping to an appropriate key frame you can later identify in your ripped video stream, otherwise you won't be able to get perfect sync in the video rips, which you need to do, because games use freeze frames and seek directly to target locations. As long as an initial reference rip exists which has the correct time correlation, other people can rip the video again later as many times as they want on any laserdisk player using any capture card, but at least one "baseline" correlation rip needs to exist which has accurate video sync, which is what I can provide. I'm also planning to rip the video timecode information in the vertical blanking interval, which is not a simple thing to do, and I'm hooking into the hardware to skim the composite signal directly from the video decoder, and I'm planning to make and release lossless rips, so I really doubt there'll be a need to do another rip (unless you want to try and to a full RF rip directly from the laser pickup), but if there is, with my one as baseline, anyone can do it even if they don't have a LaserActive.


That isn't even the biggest issue here though. Dumping the games is the first step in preserving them, and in a lot of ways, the easiest one. There's absolutely no way to use these dumps on the real hardware though, they're only useful for emulation, and in order for emulation to occur, we need to reverse-engineer and document the hardware. Too often this step gets forgotten. I've been actively working on this, and it's critical it gets done along side the dumping process. The thing is, there are maybe a handful of people who know the Mega Drive hardware as well as I do, and to my knowledge, I'm the only one of them who has a LaserActive. Nobody can emulate the LaserActive until the hardware is documented. Disassembling bioses and game dumps can yield a lot of information, but it's always going to leave a lot of blanks. Hardware tests are essential here. I really honestly believe it's up to me to do this part. If someone else had the means and inclination to do it, it would've happened by now.

Unfortunately, I only have a single MegaLD game, Space Berserker, which gives me a limited scope under which to observe the hardware in action. Space Berserker is a CLV disk that contains two tracks, the first contains all the digital data, running from the beginning of the track to the end, and the second contains all the video and audio for the game. That's quite a simple setup. Other games could be a lot more complex, and from what I've heard, they are. From my study of the hardware, I believe for example, that you could theoretically embed digital data within regions of a single track, with some sectors containing data, and others containing digital audio, possibly switching on a frame by frame basis. Seeing an example of this could yield a lot more info. I need to see examples of different audio track configurations. I have to see if any laserdisk games are stored as CAV, if so, frames will be addressed differently in that case, and seeking will be different. I need to see how the LaserActive hardware handles that.


So basically, there is a related goal of this dumping process, which is to give me a chance to perform additional hardware tests using each game. This is probably the one and only chance to get this work done, without which, emulation may never happen.

 

Any other Laserdisc player won't do unfortunately, at least, not without starting from scratch. A MegaLD stores the digital data encoded into one of the digital audio tracks. Theoretically, you should be able to capture this lossless on another player somehow and extract it, but nobody's done it. The LaserActive is a much easier option. It contains all the hardware to separate this data stream and easily provide it to the PAC-S1/S10 module, which I can control and use to stream the data directly to a computer. Any other laserdisc player is a whole separate process, when it comes to the digital data at least.

 

No, unfortunately. Reading a CD and an LD on the hardware are two totally separate things. They're basically like two totally independent systems in a single box. There's no way to get the LaserActive to read LD content from a CD, and from a technical point of view, that wouldn't even really be possible on a normal CD drive, since an LD uses analog video and audio streams.

 

Even if you were to magically burn the data onto a CD in a readable way, there would be side effects. An excellent example would be those old Don Bluth LD games. They're virtually seemless on the original hardware, but this is due to direct data access. If you play any of the DVD rereleases on a DVD player, you're in for a rude awakening.

We're so used to living in a world of abstraction it's hard to remember what's going on at a hardware level. CDs have more overhead than LDs, a completely different file system and access method, and are read by hardware in a unique way. To the end user it's just bulk media, but not on the disk surface.