Emulating Pioneer LaserActive (Mega-LD) games

Moderator: Mask of Destiny

lloydcom
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Hi and question

Post by lloydcom » Mon May 25, 2009 5:29 pm

This is my first post, as I was interested in the discussion, so Hello.

Would this LaserActive emulation attempt be done in Mess and utilise the functions of the MAME core?

Also maybe you should chat with the Daphne developers, they have more information regarding laserdisc capture.

I'm sure we would all like to have a chance to see Time Gal, at least a version that looks better than the PSX copy. :)

I know this is off topic but does anyone know if they are emulating the laserdisc side of the MSX Palcom system?

Thanks

www.daphne-emu.com

LocalH
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Post by LocalH » Fri Jul 03, 2009 4:32 pm

For everyday use (i.e., non-preservation) I would recommend using some sort of lossy compression (yes, I know, that allows the same type of situation as with ISO+MP3, but then again lossless captures of analog video are absolutely massive, and would also be losslessly "preserving" the composite artifacts inherent to the storage medium). By all means archive the large MAME-style CHDs for preservation, but who has the hard drive space to store GB upon GB of video for these games?

I would suggest something mature like I-frame only MPEG-2, pretty much any computer purchased in the last five years comes with an MPEG-2 decoder already installed, and even for those who don't run Windows/OSX or don't have MPEG-2 decoders installed, there are fairly simple solutions that can be either bundled with the emulator or pointed to by a handy guide. Plus, for the lossy version, you can also do a little processing to the video to make it more friendly to compression (and thereby increase quality at lower filesizes) - remove luma/chroma crosstalk, fix levels to compensate for the difference between NTSC TVs and PC monitors, etc. Also, if you have a little older computer that is still powerful enough to handle this, but may not be able to handle SATA drives or PCI-E cards, then you may not have either the HD or memory bandwidth to handle streaming that much lossless data on top of having to emulate two 68ks and a Z80 (not to mention the rest of the system).

Insofar as the video content on MegaLD games - I want to advocate against any deinterlacing whatsoever. If the video doesn't contain 50/60fps content, then it doesn't need deinterlacing at all, and if it does contain such content, then deinterlacing will cause us to lose 50% of the image data (except for low-motion scenes where the deinterlacer doesn't need to fill in missing lines). Most computers that can handle MegaCD emulation can probably also handle at least a dumb bob deinterlace in realtime on top of that (which is basically interlace "emulation", i.e. it shows flickering just like actual interlacing). Anything other than this can be included as an option but should definitely be done in realtime so the user can select the deinterlacing algorithm that provides the best quality on their machine while still being able to actually play the game.

I know from playing them years ago that at least SEGA's arcade LD titles used smooth, fluid 60fps content, so it would not surprise me if MegaLD titles did too, so I just wanted to bring that point up and make sure you guys were aware of that on the video side of things.

Another question: Are MegaLD games CLV or CAV? CLV allows more video to be crammed onto the disc as you reach the outer edge, while CAV discs are limited to one frame per revolution, or 54000 frames total. Due to the need to address individual frames (to branch to different video clips as per gameplay or for menus, attract modes, etc), I'm gonna guess CAV.

Xavier
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Post by Xavier » Wed Sep 30, 2009 4:37 am

Hey I dumped the laseractive bios a couple years ago.
I have a bulk of the libaray, (I have 14 games) and would like to dump the Ld's as well.
I used Mask Of Destineys SegaCd program to dump it and asked him if he could alter the code to make this project viable he said he'd try but I havent heard back from him since. I just wrote him again.
I asked Snake if he could alter the code so It'd accept the laseractive bios, currently it crashes after a second. He never wrote me back, or responded to my thread.
On my end Ill start tring to figure out how Ill capture the video. I'm a stickler for quality so Id like to capture it in its native resolution but I want to use some sort of compression agent like Divx. In a dream world Id like to caprture it digitally but countless people have said that laserdiscs are strictly analog. I guess if it was possible Daphne would have done it allready.

I also have a Msx palcom and would like to do the same thing with it but I only have 3 games so far.

Anways Mask OF Destiney, Snake or anybody else who could help out pleases email me.

TascoDLX
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Post by TascoDLX » Sat Oct 03, 2009 12:44 pm

I wish I had time to work on this. It shouldn't be difficult to read the digital tracks (data & audio). Dumping them (reliably) might be a pain, though. I'll have to see if I can find some time.

Xavier
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Post by Xavier » Mon Oct 05, 2009 2:31 am

Yeah I can do alot from here if Snake would give support in Fusion for the bios I dumped and If I could get the updated program from Mask Of Destiny.
Haven't heard back from him yet.

8bitwizard
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Post by 8bitwizard » Mon Oct 12, 2009 1:03 pm

Xavier wrote:but I want to use some sort of compression agent like Divx. In a dream world Id like to caprture it digitally but countless people have said that laserdiscs are strictly analog. I guess if it was possible Daphne would have done it allready.
Laserdisc video is very analog. The audio should be digital (there are two analog and two digital audio tracks), but you will have to use the PCM optical out of the player to rip that bitstream, and I don't think it's possible to rip the TOC without writing a ripper program to run on the 68000 CPU.

(Note that when a laserdisc has Dolby Digital, it is encoded into one of the analog channels, and requires an external decoder because only the raw analog channel signal is output by the player. To my knowledge, no LD player was ever made with a DD decoder built in. But Laseractive discs did not use Dolby Digital, so this won't matter to you.)

LocalH
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Post by LocalH » Wed Oct 14, 2009 1:43 pm

Best resolution for LD capture is 720x480 MPEG-2 (or possibly 640x480).

bakudandan
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Post by bakudandan » Tue Dec 01, 2009 11:02 am

I'm interested in this. I've got a Laseractive to donate and both region PAC's. If someone needs it I'll send it for the price of shipping.

Edit: Of course we'd need some kind of consensus as to who here would benefit the most from having one

TmEE co.(TM)
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Post by TmEE co.(TM) » Tue Dec 01, 2009 11:39 am

I would love to draw some schematics and work out some mods (especially regarding sound :P)...
Mida sa loed ? Nagunii aru ei saa ;)
http://www.tmeeco.eu
Files of all broken links and images of mine are found here : http://www.tmeeco.eu/FileDen

bakudandan
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Post by bakudandan » Wed Dec 23, 2009 6:07 am

TmEE co.(TM) wrote:I would love to draw some schematics and work out some mods (especially regarding sound :P)...
Hey, if you can write a working emulator based on that, I'm sold. No one's even dumped anything yet though so I guess no one's really interested in this for the time being.
I might record through some of these games for youtube later. These things are barely interactive anyway, you wouldn't really be missing anything :roll:

TmEE co.(TM)
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Post by TmEE co.(TM) » Wed Dec 23, 2009 3:21 pm

writing emulators is not exactly my business, I'm more of a hardware guy :P
Mida sa loed ? Nagunii aru ei saa ;)
http://www.tmeeco.eu
Files of all broken links and images of mine are found here : http://www.tmeeco.eu/FileDen

Chilly Willy
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Post by Chilly Willy » Wed Dec 23, 2009 6:09 pm

Writing emulators tends to be MY business, but doing so requires info. If there were more info on the LD, I could probably do something.

bakudandan
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Post by bakudandan » Thu Mar 11, 2010 11:30 pm

bump

DogOnTheNet
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Post by DogOnTheNet » Mon Jun 07, 2010 7:02 am

Hi i'm new here, found the thread searching for LaserActive Emulation. Not much discussion elsewhere. Just wanted to share a tidbit that I assumed someone else would have brought up by now but in the handful of glancing around the internet so far i'm not seeing it mentioned so maybe this will be useful to someone?


It should not be too difficult to get the ROM images off an LD-rom disc because it should just be stored as the standard CD-style digital audio stream. LaserDiscs have video, analog audio, and CD-quality audio. You shouldn't even need a LaserActive. I'm guessing any normal Laserdisc player that has a digital out for the audio should actually run it - the PCM bitstream is probably exported unchanged in players at that time. Put in an LD-ROM and hit play, i'm guessing any soundcard that allows a digital in (dont know if that includes Soundblaster but pretty sure i've seen some older generation prosumer cards that did - MIDIMAN and such even back to the ISA models like D-MAN). As long as no processing is applied and the card doesnt mind recording direct digital in (SCMS if it were applied may interfere with low end consumer cards but typically was ignored on prosumer gear) i'd think it would work. Or at least be worth trying first.

If that didnt work it would just be a matter of ripping the signal to a PC (i'm guessing the electronics to sync to the signal and read in data via the parallel port or using some slightly more professional signal acqusition and recording gear). Any overhead like control bits or Serial Copy Management System should still be stripped out by prosumer hardware, the "WAV" file would probably be like the "WAV" file that makes up a Sega CD first track - in reality digital code, not audio. I'd be very surprised if the file format is substantially different than the Sega CD especially when Sega CD's were I think supposed to run on the LA automatically. You might even 'test' your data ripping using a Sega CD image acquired the same way (on a combo LD/CD player) that's already been ripped to ISO to see if it's ripping accurately or whether there's any possible header bits or something that somehow are accidentally getting added.

Being able to use any LD player (with digital out) would be a plus since I wouldn't want to hack around on a player costing $1200 on ebay if I could help it.

It shouldn't matter but as extra info i'm guessing all Sega LD-ROMs will be CAV format. (if anyone has a picture of the discs you can usually even see the difference - on a CAV you can sorta see the disc split into two 180 degrees apart because one rotation of the disc is like two fields/one frame, this is what allowed the easy special effects in the age before digital frame storage. The disc would rotate at a fixed speed and just keep playing the same analog track without advancing the laser pickup to the next track.) Digital framestore wouldn't have been common at this time, as the CLV players which allowed CAV-like special effects I think didn't come out til a few years later.


FWIW the same method should work on the Turbografx-16 based LD-ROMs as well (feel free to repost this to a TG16 board if anyone frequents both, i'm a sega man so i'm only posting here :) ), and for that matter the karaoke PAC should work the same. The only remaining analysis would be to see if there is any different hardware on the Sega CD vs the LD-ROM unit.

Is this info new or useful to anyone in the emulation scene?

Someome mentioned already ripping the LD BIOS, the only other requirements should be if there are any hardware changes or upgrades or new chips.

bakudandan
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Post by bakudandan » Fri Jul 23, 2010 4:05 am

Recording it directly off a regular laserdisc player won't work, there are usually simultaneous video streams which are only separated when played in the Laseractive (for example gameplay & death scenes) not to mention the hybrid 3D/2D games where the 2D mode is just the 3D images converted by the Laseractive

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