Software MSX-driven Laserdisc player

What is the protocol that the MSX uses to talk to the Laserdisc player originally?

I was just thinking, that maybe with an Rasp Pi or similar, you could use the GPIO pins to read and support the native protocol? But those mini-computers don't have the necessary video output(s), I think, and also that would not work with every PC out there (but, a lot of new motherboards do not have serial ports, either, and if they do, it is only as a header). But, if this is going to require extra hardware in any case (self-made cables etc.), it's something to consider as an alternative - no need to patch the ROMs.

(I could be totally lost with what the GPIO pins can be used for, I must admit...)

Thanks Pentarou, Eric's project is almost the same as what I had in mind

I'd like this to be the more "generic" as possible, that's why I first favored the "desktop" solution compared to Raspberry. The main question here is the composite output, that might not be so easy to get on modern PC video cards (or you'll need VGA to composite converters...). I'm wondering about the Raspberry's ?

Also, I'm not sure if the communication between the MSX and the Laserdisc is bi-directionnal or not ? I was assuming that the MSX was only sending commands to the Laserdisc ("go to the chapter or time index"), but there might be some extra sync signals ?

About the serial port for PC input, you can find some very cheap "serial port to USB" converters on eBay, so that's not a real blocker. If anyone has a solution using USB port directly, I'd be interested (but I think the soldering might not be so easy compared to soldering a MSX joystick port to a PC serial port).

AFAIK the protocol is exactly like a remote control (so one direction). See the openMSX sources for details!

I don't know if all the "commands" would be supported by a remote controller (like jumping directly to a specific chapter or time). And that would be remote controller specific, and you'll need a DVD player with a converted laser disc image. Still an interesting idea though.

Hello guys,

My own project (FMV Game system) has stalled for now. I loose my first source code, thus I had to re-write it, but in fact my second code was not as accurate as the first one !! and no time for now to work again on it.

It's not so simple to drive laserdisc game's image from MSX....

First, this is not possible to use DVD based game.
-> Laserdisc have the ability to jump directly and instantly to a specific time code, DVD cannot do that !
DVD are based on chapters. Thus, if you want to use a DVD player you have to cut your game movie into chapters...
But, the time a DVD player take to jump to a chapter is quite long. Even hight end DVD players take 1 to 2 seconds to jump
to a chapter. it is too long for this type of game.

->My solution was to use a PC with an composite video out.
The Movie Player on the PC must be able to jump on any time code of the video file, like a Laserdisc player do.
Most of the PC Video players do not do that. They jump 10secondes by 10seconds for example...
The videoplayer I used and had this ability is MPLAYER (http://www.mplayerhq.hu/design7/news.html)

-> Using a RaspberryPi is a solution. It have a video composite output. But the probleme is to find a videoplayer for Raspberry pi that can jump to any time code... MPLAYER is not available for the Raspberry...

-> The communication problem...
You have 2 way to do :
- First, the MSX is calculating all. MSX launch the video game, and have a table of all events in the game, also it knows all time code to jump. Thus the MSX must calculate exactly the passing time, and request events from the player.
In a one way communication system (MSX -> PC), MSX is totaly blind to the Video Player ; it doesn't know if the video is really at the good time code, and if all is going well (it's quite hazardous).
If you have a two way communication (MSX <-> PC) you can request from the PC the actuall time code it play, and have a very accurate control of what the video player do. In this case you indeed need a fast communication interface between MSX and PC.

- Second way to do : The PC is calculating all. The PC knows all events in the game, and knows all time code to jump.
The PC launch the video game, control the video, and it send request to the MSX when a player request is need.
If the request is send back to the PC in time the video game continue, if not, the PC player jump to a end-sequence time code.
This is my own solution. It need a two way communication interface, but it not need a really fast one because data to transfert are limited.