Issue with M3U files

[Special T]

• System - Sega CD
• RetroArch Core - Genesis Plus GX
• Sega CD Game Format - CHD
• LaunchBox Additional Apps Setting - metadata section shows each disc is labeled as 1 & 2
• LaunchBox Manage Emulator - Sega CD / Genesis Plus GX has the "Use M3U Playlists for Multiple Discs" option enable

If I attempt to launch a multi-disc game (Prize Fighter or Dracula Unleashed) nothing happens at all i.e. RetroArch doesn't appear

If I attempt to launch a single disc game, it works without issue, RetroArch launches like normal and the games plays like it should.

If I attempt to load one of the multi-disc games into RetroArch directly (not through LaunchBox) the games will load successful.

Multi-disc games do work with other systems through LaunchBox e.g. Sega Saturn using the Mednafen core.

Looking at the RetroArch documentation, it looks like Genesis Plus GX supports M3U files and CHD files. 

 

Can anyone tell me what I might be doing wrong or double check to see if they can launch multi-disc Sega CD games with the Genesis Plus GX core.

[faeran]

Based on a few searches, it looks like the issue is the core doesn't like absolute paths to be inside of their m3u files. It's some limitation to the core's implementation of m3u files.

[Special T]

Is that something I can fix on my end within LaunchBox settings or would the solution be to manually create m3u files for that core?

[faeran]

1 hour ago, Special T said:

Is that something I can fix on my end within LaunchBox settings or would the solution be to manually create m3u files for that core?

If you would like to use m3u files for this core, you're likely going to need to set up a manual file.

[damageinc86]

has anyone got this working? my m3u when launched with launchbox just shows retroarch with a black screen. It looks like now retroarch can handle m3u lists, and I have a game with 2 discs .CHD in an m3u playlist.  pointing launchbox to the playlist instead of the Disc 1 entry.  It works when I launch disc 1 on its own.  But nothing at all when i launch the m3u. 

Edited July 20 by damageinc86

[C-Beats]

2 hours ago, damageinc86 said:

has anyone got this working? my m3u when launched with launchbox just shows retroarch with a black screen. It looks like now retroarch can handle m3u lists, and I have a game with 2 discs .CHD in an m3u playlist.  pointing launchbox to the playlist instead of the Disc 1 entry.  It works when I launch disc 1 on its own.  But nothing at all when i launch the m3u. 

M3U support last I knew is core dependent. What core you attempting to load the games with?

[damageinc86]

1 minute ago, C-Beats said:

M3U support last I knew is core dependent. What core you attempting to load the games with?

Genesis plus gx.  

[C-Beats]

1 hour ago, damageinc86 said:

Genesis plus gx.  

Well damn there goes that line of thinking lol. Was hoping it was something easy like the core didn't support it... According to the docs though looks like it should. What game you playing on that core that is multi-disc? None immediately stand out to me as even having it (thought I admit it's been a while since I've looked into those systems)

[damageinc86]

5 minutes ago, C-Beats said:

Well damn there goes that line of thinking lol. Was hoping it was something easy like the core didn't support it... According to the docs though looks like it should. What game you playing on that core that is multi-disc? None immediately stand out to me as even having it (thought I admit it's been a while since I've looked into those systems)

This is my m3u:  

Dracula Unleashed (Disc1) (USA).chd
Dracula Unleashed (Disc2) (USA).chd

Yeah, that's why it made no sense to me, because i've seen that this core supports it.  Don't know if there's anything else inside retroarch I need to activate or what.  But it's just a black screen and retroarch never starts.  First disc starts fine on it's own if i point launchbox to it.

[Special T]

That's the same set up I have and mine works fine however my discs are labeled differently so, my m3u file looks like this

Dracula Unleashed (USA) (Disc 1).chd

Dracula Unleashed (USA) (Disc 2).chd

 

RetroArch v 1.21.0 loads the first disc (chd) as it normally would and I can change it to the second disc in the menu by pressing F1 and changing the disc to 2.

[damageinc86]

On 7/20/2025 at 9:39 AM, Special T said:

That's the same set up I have and mine works fine however my discs are labeled differently so, my m3u file looks like this

Dracula Unleashed (USA) (Disc 1).chd

Dracula Unleashed (USA) (Disc 2).chd

 

RetroArch v 1.21.0 loads the first disc (chd) as it normally would and I can change it to the second disc in the menu by pressing F1 and changing the disc to 2.

Maybe it's a hidden setting in launchbox emulator setup or something.  But I just re-named to your style, and my m3u is Dracula Unleashed (USA).m3u with lines just like yours. rom files renamed to match.  and it is still just a black screen in retroarch.  nothing happening. 1.21.0 as well.  I even have "use m3u playlist" check marked in the edit emulator window. unless there's some default command line parameters that aren't in there, or something.  I have no clue.

Edited Friday at 01:01 AM by damageinc86

[fromlostdays]

Uncheck "use m3u playlist" for sure. I believe that feature attemps to create m3us on the fly. If you've imported the m3u just like you would a rom, you don't need to check it. Thats probably your problem right there. 

If that doesn't work, next step is to open Retroarch, load the core, then manually launch the m3u. If that works, we know its a launchbox setting. If it doesn't, we know theres probably something wrong with the m3u itself. But I'm pretty sure the above will fix your problem.

And you don't need any special command line parameters. I'm only saying this because I know when something isn't working it gets frustrating and we can start overthinking it. Launchbox should treat an imported m3u the same as if you imported the rom directly. There's really nothing extra to it. Either that setting is your problem or there has to be something wrong with the m3u.

 

Edited Friday at 04:43 AM by fromlostdays

[damageinc86]

yeah i only checked that because i thought it might make a difference.  unchecked.  no dice.  also launched m3u in retroarch, black screen. nothing happening. weird.  not much i can do about the m3u, it's just two entries that match the roms lol.  So, must be some retroarch thing I have no clue about now.

Edited Friday at 05:28 PM by damageinc86

[Special T]

Not sure if it will help but here are screenshots from my setup

[fromlostdays]

First, I'm testing to see if I can attach m3u files here, you don't have to interact with it. It seems to have let me do it, so @damageinc86 can you attach your m3u file here? A screenshot of your games directory in details view would also help. 

I went ahead and generated m3us for my sega cd collection and am launching this exact game in chd format from an m3u with this exact core and it works. The fact that it doesn't work for you in retroarch basically ensures the problem isn't in a launchbox setting, so we can eliminate those. I can only think of two other possibilities now:

1: You're messing up this m3u or missing a detail over and over - I'm not making fun of you. This happens especially in this hobby when you're staring at the same things constantly - sometimes we see what we think we should see instead of whats actually there. I know all about it. To that end, attach your m3u file here, and a screenshot of your roms directory in details view - or type out the exact rom names and extension here at least. 

2: MAYBE theres some core setting in the core thats interfering with this. I want to look at number 1 closely first, but there is a simple way to test if this is happening. We'll do that next if we have to.  

This should absolutely work, something simple is wrong here we just have to isolate. Don't be disheartened.

Dracula Unleashed.m3u

Edited yesterday at 07:54 PM by fromlostdays

[damageinc86]

12 hours ago, fromlostdays said:

First, I'm testing to see if I can attach m3u files here, you don't have to interact with it. It seems to have let me do it, so @damageinc86 can you attach your m3u file here? A screenshot of your games directory in details view would also help. 

I went ahead and generated m3us for my sega cd collection and am launching this exact game in chd format from an m3u with this exact core and it works. The fact that it doesn't work for you in retroarch basically ensures the problem isn't in a launchbox setting, so we can eliminate those. I can only think of two other possibilities now:

1: You're messing up this m3u or missing a detail over and over - I'm not making fun of you. This happens especially in this hobby when you're staring at the same things constantly - sometimes we see what we think we should see instead of whats actually there. I know all about it. To that end, attach your m3u file here, and a screenshot of your roms directory in details view - or type out the exact rom names and extension here at least. 

2: MAYBE theres some core setting in the core thats interfering with this. I want to look at number 1 closely first, but there is a simple way to test if this is happening. We'll do that next if we have to.  

This should absolutely work, something simple is wrong here we just have to isolate. Don't be disheartened.

Dracula Unleashed.m3u 76 B · 0 downloads

yeah, it must be something in retroarch, since it's also a black screen there, outside of launchbox.

Opening both of our m3u files in notepad++ and switching tabs back and forth shows no difference.  So I have the same m3u.  Roms: Dracula Unleashed (USA) (Disc 1).chd & Dracula Unleashed (USA) (Disc 2).chd

launchbox settings same as yours.

It's gotta be something inside retroarch somewhere.  Want to just do an anydesk remote session so you can get into my retroarch directly and see?

 

 

[Special T]

I don't recall at what point I switched over but I'm using Genesis Plus GX wide and here are some screenshots from my retroarch settings with Dracula up and running

Edited 8 hours ago by Special T

[fromlostdays]

7 hours ago, damageinc86 said:

yeah, it must be something in retroarch, since it's also a black screen there, outside of launchbox.

Opening both of our m3u files in notepad++ and switching tabs back and forth shows no difference.  So I have the same m3u.  Roms: Dracula Unleashed (USA) (Disc 1).chd & Dracula Unleashed (USA) (Disc 2).chd

launchbox settings same as yours.

It's gotta be something inside retroarch somewhere.  Want to just do an anydesk remote session so you can get into my retroarch directly and see?

I don't know what anydesk remote session is, but I'm not adverse to it. However, I wouldn't be able to say which setting breaks m3u support in the core. Comparing your settings to the above working version would be faster. I CAN say that "CD Image Cache" should definitely be OFF, as above. So double check that first. I'm pretty sure that can break m3us as it might try to cache both disks at the same time.

If that is already set to off, and all the other settings match the above and it STILL doesn't work, I recommend downloading a new portable install of retroarch. Oh that reminds me - Core support for m3u wasn't always a thing. So use the online updater to update your core if you haven't. If you're running an older version that might be the cause. Anyway, stock settings for this core run m3us fine so downloading a new portable installation of RA just to test will tell us if its an RA setting, or something to do with the m3u file (a crazy special character or something).