Emulating Pioneer LaserActive (Mega-LD) games

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KanedaFr
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Post by KanedaFr » Wed May 23, 2012 10:54 pm

LAPProject wrote:Hello,
Due to the rarity of these discs, I propose that we all work together to get as many games dumped and recorded as possible. Whether or not that should be under a new forum or other kind of discussion community is anyone's guess.
if you need a dedicated forum, just tell me
I'll be happy to open one like I did for Regen

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Post by MNc99 » Wed May 23, 2012 10:57 pm

I think it'd be a good idea, since this looks like it might be quite a large undertaking. If you open the floodgates now it'll encourage new users to sign-up and offer their services.

EDIT: Might be worth making it clear, we need dumpers for NEC games as well as just the SEGA Mega-LD format games.
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Post by LAPProject » Thu May 24, 2012 1:12 am

MNc99 wrote:I think it'd be a good idea, since this looks like it might be quite a large undertaking. If you open the floodgates now it'll encourage new users to sign-up and offer their services.

EDIT: Might be worth making it clear, we need dumpers for NEC games as well as just the SEGA Mega-LD format games.
Will the Mega-LD dump method work for LD-ROM games?

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Post by Nemesis » Thu May 24, 2012 1:44 am

I believe it will. As long as the data storage method is the same, which it almost certainly is, it will work, however this is untested, as I don't have any LD-ROM games at my disposal right now.

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Post by Nemesis » Thu May 24, 2012 1:46 am

KanedaFr wrote:
LAPProject wrote:Hello,
Due to the rarity of these discs, I propose that we all work together to get as many games dumped and recorded as possible. Whether or not that should be under a new forum or other kind of discussion community is anyone's guess.
if you need a dedicated forum, just tell me
I'll be happy to open one like I did for Regen
Yeah, a dedicated forum is probably a good idea. If nothing else, it'll make the releases easier, since when the games start getting dumped, we can make a separate thread per release, and like MNc99 said, it might give the project a bit more appeal, make more people willing to get involved.

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Post by Misty » Thu May 24, 2012 1:48 am

LAPProject wrote:
MNc99 wrote:I think it'd be a good idea, since this looks like it might be quite a large undertaking. If you open the floodgates now it'll encourage new users to sign-up and offer their services.

EDIT: Might be worth making it clear, we need dumpers for NEC games as well as just the SEGA Mega-LD format games.
Will the Mega-LD dump method work for LD-ROM games?
I believe Nemesis said it would, yes.

EDIT: Ninja'd by Nemesis!

If not - I've already volunteered to help with dumping, and I own both Sega and NEC modules.
LocalH wrote:One thing I was thinking of - it was stated earlier in the thread that some discs contain two interleaved video streams. The only realistic way that I see this to be the case is if the two streams are stored as alternating fields.
That is exactly what I was talking about, yes! Only a minority of games do that - from what I've seen so far, Blue Chicago Blues and Road Prosecutor. (Blue Chicago Blues is kind of oddball in general; it also uses its digital audio track BOTH for LA data and for standard LD digital audio. Every other game I've seen reserves the digital audio track for data and uses analogue audio exclusively for audio.)

Curiously, the other games I own are all full-res video even though they all run in low-res mode for the sake of PAC graphics. It looks like they just drop the other scanlines. I guess that means an emulator could theoretically run at higher res than the real thing does. ;)

Aside from dumping, I'd also be glad to record video off my higher-end LD player if there's any interest in that. The LA is, sadly, renowned for having pretty crappy LD video - I believe I heard it does an internal separation from composite (off the disc) to luma/chroma for combination with the PACs, then back to composite for output.

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Post by Nemesis » Thu May 24, 2012 2:00 am

Aside from dumping, I'd also be glad to record video off my higher-end LD player if there's any interest in that. The LA is, sadly, renowned for having pretty crappy LD video - I believe I heard it does an internal separation from composite (off the disc) to luma/chroma for combination with the PACs, then back to composite for output.
Thanks for the offer. Anyone can have a go a the video ripping if they want, but there are going to be two main obsticles to doing it yourself:
1. Capture hardware. Cheap capture cards just aren't going to cut it. If you have a better player, but a worse capture card, chances are the result is going to be worse. You need a card that gives stable sync with the video, and can capture without compression/deinterlacing.
2. Synchronization. You need to know, for sure, which precise video frame in your ripped video stream matches up with which sector number on the disk when the game issues a seek command, which is a little difficult, since you have to worry about pre-seeking and such. I have a plan on how I'm going to do this, but it's quite a fiddly, manual process, and I'm not sure it's something that could easily be automated. This is still something I need to run a few tests to be sure about.

I don't have any other LaserDisk players to test on, but I'm fairly sure the video degredation you're talking about on the LaserActive only occurs when the digital buffer is enabled, which it needs to be in order to combine the analog video signal with the Mega Drive graphics. The video signal is noticably affected when the digital buffer is enabled. I'll be ripping the video tracks with the digital buffer turned off however, so I'm hoping this is comparable to any other LaserDisk player. Even if it isn't, I might not have a choice, since I may need to do the ripping on the LaserActive in order to solve the synchronization issue. I'm not certain on that point yet though.

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Post by MNc99 » Thu May 24, 2012 2:03 am

Misty wrote:I guess that means an emulator could theoretically run at higher res than the real thing does. ;)

Aside from dumping, I'd also be glad to record video off my higher-end LD player if there's any interest in that. The LA is, sadly, renowned for having pretty crappy LD video - I believe I heard it does an internal separation from composite (off the disc) to luma/chroma for combination with the PACs, then back to composite for output.
This. Dear god, a million times this. LD playback at resolutions superior to the original? It's every emulation fan's wet dream.

Has anyone given any thought as to whether something like ReGen or Kega would support this, or if we'd need to make our own program? DAPHNE is open-source, perhaps that would be a good place to start if there are any coders around.
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Post by Misty » Thu May 24, 2012 2:05 am

Nemesis wrote:1. Capture hardware. Cheap capture cards just aren't going to cut it. If you have a better player, but a worse capture card, chances are the result is going to be worse. You need a card that gives stable sync with the video, and can capture without compression/deinterlacing.
I've got a decent Blackmagic capture device, so no issues there. I can capture uncompressed or losslessly.
2. Synchronization. You need to know, for sure, which precise video frame in your ripped video stream matches up with which sector number on the disk when the game issues a seek command, which is a little difficult, since you have to worry about pre-seeking and such. I have a plan on how I'm going to do this, but it's quite a fiddly, manual process, and I'm not sure it's something that could easily be automated. This is still something I need to run a few tests to be sure about.
I definitely need to check into that - it concerned me too. May not be possible capturing video only, though I can at least make sure that there are no dropped/inserted frames.
I don't have any other LaserDisk players to test on, but I'm fairly sure the video degredation you're talking about on the LaserActive only occurs when the digital buffer is enabled, which it needs to be in order to combine the analog video signal with the Mega Drive graphics. The video signal is noticably affected when the digital buffer is enabled. I'll be ripping the video tracks with the digital buffer turned off however, so I'm hoping this is comparable to any other LaserDisk player. Even if it isn't, I might not have a choice, since I may need to do the ripping on the LaserActive in order to solve the synchronization issue. I'm not certain on that point yet though.
That's good to know. If the luma/chroma issue is in fact a separate degradation (to my understanding, the unit always does that regardless of digital buffer, etc.), then that part can't be avoided - but it sounds like the digital buffer is the larger source of degradation.

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Post by MNc99 » Thu May 24, 2012 2:10 am

BlueBMW wrote:EDIT:

Did some looking over the schematic.... looks like we might want to look at the LD video inputs at the BA7230LS chip on the RGBB board. That chip looks to be the final encoder that combines the LD video with the RGB overlay from the PAC.

Schematic: http://www.cyberroach.com/new_laseracti ... age059.gif

Datasheet for the BA7230LS: http://pdf1.alldatasheet.com/datasheet- ... 230LS.html
Just reposting this in case it's of any help to anyone.

By the way, Nemesis, did you ever find out if the other games besides Space Berserker have 'fuck' in the code? That'd be hilarious to see.
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Post by Nemesis » Thu May 24, 2012 2:16 am

Has anyone given any thought as to whether something like ReGen or Kega would support this, or if we'd need to make our own program? DAPHNE is open-source, perhaps that would be a good place to start if there are any coders around.
Well I'm working on my own Mega Drive emulator, but it's a long way off from MegaLD support. Adding MegaLD support to Daphne isn't really an option. The Mega Drive/MegaCD hardware is the most complex part of this system. Emulators that already support the MegaCD are well placed to be able to add in MegaLD support relatively quickly, but that said, expect it to take a little while. There's at least one completely unknown brand new controller chip which needs to be reverse-engineered in order to emulate the system. As more games are dumped, those reverse engineering efforts will move forward with more sample code being made available, and I can of course always run tests on the hardware, but the first priority is dumping the games.

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Post by Nemesis » Thu May 24, 2012 2:17 am

By the way, Nemesis, did you ever find out if the other games besides Space Berserker have 'fuck' in the code? That'd be hilarious to see.
I haven't dumped any more games yet, so I guess we'll just have to wait and see on that point. :)

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Post by MNc99 » Thu May 24, 2012 2:19 am

Nemesis wrote:
Has anyone given any thought as to whether something like ReGen or Kega would support this, or if we'd need to make our own program? DAPHNE is open-source, perhaps that would be a good place to start if there are any coders around.
Well I'm working on my own Mega Drive emulator, but it's a long way off from MegaLD support. Adding MegaLD support to Daphne isn't really an option. The Mega Drive/MegaCD hardware is the most complex part of this system. Emulators that already support the MegaCD are well placed to be able to add in MegaLD support relatively quickly, but that said, expect it to take a little while. There's at least one completely unknown brand new controller chip which needs to be reverse-engineered in order to emulate the system. As more games are dumped, those reverse engineering efforts will move forward with more sample code being made available, and I can of course always run tests on the hardware, but the first priority is dumping the games.
Bah!
Can't you internet people I've never met just work over-time to satisfy my demands?
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Post by Misty » Thu May 24, 2012 2:21 am

MNc99 wrote:
BlueBMW wrote:EDIT:

Did some looking over the schematic.... looks like we might want to look at the LD video inputs at the BA7230LS chip on the RGBB board. That chip looks to be the final encoder that combines the LD video with the RGB overlay from the PAC.

Schematic: http://www.cyberroach.com/new_laseracti ... age059.gif

Datasheet for the BA7230LS: http://pdf1.alldatasheet.com/datasheet- ... 230LS.html
Just reposting this in case it's of any help to anyone.

By the way, Nemesis, did you ever find out if the other games besides Space Berserker have 'fuck' in the code? That'd be hilarious to see.
Also relevant:

http://www.gamesx.com/misctech/laseractive.htm
http://www.gamesx.com/misctech/laseractivergb.htm

Instructions on adding s-video and RGB output by tapping the video before it gets combined with the PACs or builtin display.

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Post by Misty » Thu May 24, 2012 2:22 am

Nemesis wrote:
By the way, Nemesis, did you ever find out if the other games besides Space Berserker have 'fuck' in the code? That'd be hilarious to see.
I haven't dumped any more games yet, so I guess we'll just have to wait and see on that point. :)
I'm going to assume that's a standard part of the LA spec. ;)

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