[HELP] Can't find path when launching from Pegasus frontend

[SoumyBhow]

I've setup MelonDS in Pegasus frontend with the following launch code:
command: am start --user 0
-a android.intent.action.VIEW
-n me.magnum.melonds/.ui.emulator.EmulatorActivity
-e PATH "{file.path}"

However, when launching a game, MelonDS opens but it says it couldn't find the ROM path (attached pic)

System is Android 11 on OnePlus 7 Pro.

When replacing {file.path} with an actual ROM's directory, that game is able to launch from Pegasus, so I'm thinking it's a problem with {file.path}?
I've already made an issue on Pegasus' git (mmatyas/pegasus-frontend#878), but I thought it wouldn't hurt to see if it's an issue on MelonDS' side.

[rafaelvcaetano]

It's quite possible that this is a melonDS issue. As the message says, the ROM you are trying to load must be available in the emulator's ROM list. I know this is stupid, but with the most recent changes to Android storage access, there's no other way to ensure that the emulator can access the ROM and save file. As such, make sure that the ROM you are trying to load through Pegasus can be found in melonDS's ROM list.

If you can find the ROM in the list, then there might be an issue converting the file path provided by Pegasus to the one used by melonDS. Again, this doesn't make much sense, but it's the way Google wants to make things from now on. If this is the case, could you send me a screenshot of your ROM list in melonDS?

[SoumyBhow]

ROMs can be seen and launched from MelonDS' ROM list. All my ROMs can be seen there, and the search directory has already been added

[rafaelvcaetano]

So, I've just tested this myself and I couldn't load the ROMs with the stable Pegasus release, but it worked perfectly using the latest release (released on 2021-08-09). Which version did you test on? If you were not using the latest release, could you try it please?

[SoumyBhow]

I've been using that latest version of Pegasus all this time. I probably should've specified so my apologies. Would you mind sharing your metadata.txt or however method you used to get it to launch?

[rafaelvcaetano]

Sure. Here is the metadata.txt I used:

collection: NDS
extension: nds
launch: am start --user 0
  -a android.intent.action.VIEW
  -n me.magnum.melonds/.ui.emulator.EmulatorActivity
  -e PATH "{file.path}"

One of the things you can try is replace android.intent.action.VIEW with me.magnum.melonds.LAUNCH_ROM, but I don't think it will have any impact.

And just to make sure, are you using the alpha15-26-gfce59755 version of Pegasus?

[SoumyBhow]

Nope still the same error for me. I even downloaded the latest Pegasus APK just to be sure. Maybe there's some other part of my text file that's wrong? Would you mind taking a look at my file to see if there are any differences?
metadata.pegasus.txt

[SoumyBhow]

Little update: I've scraped my ROM's with Skraper on my PC instead of Skyscraper and that works. I guess this is a scraper issue then, but I still don't understand why. I guess I'll have to look into it myself. Nonetheless, thank you for your time.

Edit: looks like it was the path after all. Replacing the location of the ROM folder with a dot fixed it. The Metadata file stays in the same folder as my ROMs so just doing ./media/boxart for example works.

[SoumyBhow]

Hey there,

I just wanted to report that MelonDS no longer works with frontends, even after the frontend updated with scoped storage support. I've tried this out with Daijishou, which recently got an update for Uri support. Mupen64, Aethersx2 and PPSSPP, some examples of emulators that adapted scoped storage, and they work no problem, yet MelonDS doesn't. I've spoken with the Daijishou dev and they suggested using absolute paths along with scoped storage via a Java interface. What are your thoughts on this?

[rafaelvcaetano]

I've recently noticed that Dig also stopped working after adding support for scoped storage. I'll have to evaluate how to properly use the new frontend implementations.

[SoumyBhow]

Thanks for offering to look into this. Much appreciated

[MikeSeaver555]

I'm not able to make it work through ARC Browser frontend on Android 12, not sure if there are any news related to this, but the problem matches with the one described here. I know you do this for free and I'm not in position to demand nothing, I don't wan't to bother you, if it were posible I'd like to know if you're busy or you're still working on it.

[EgoBizarro]

Heya, I just wanted to report that melonDS is still not working correctly with Daijisho (don't know about other frontends). I tried all kinds of parameters, path, uri, -a android.intent.action.VIEW and me.magnum.melonds.LAUNCH_ROM... It only opens melonDS but can't find the rom to boot it.
I must be a regression, though, because someone showed me that it was working for them, but not on 0.9.5; he's gone back to 0.9.3 (and I tried 0.9.4, so I guess it got broken somewhere between those two versions).
He has it working with this:
-a android.intent.action.VIEW
-n me.magnum.melonds/.ui.emulator.EmulatorActivity
-e PATH {file.path}

[EgoBizarro]

That's it! With that it works great for me, thanks a lot! :D
To my surprise, I can even boot DSi games via Daijisho - obviously, I have to have DSi selected as default system in melonDS for them to work. BTW, does anyone here know if there's any downside to having DSi set as default system? (since it still says '(experimental)'.

[SoumyBhow]

Interesting. The fix works on Daijsho but not on Pegasus frontend. After setting everything to one line and replacing file.uri with file.documenturi, MelonDS says it coudn't find the ROM. Has anyone else managed to get this to work on Pegasus?

[jackalopy]

If what I'm seeing here https://pegasus-frontend.org/docs/user-guide/meta-files/ is right, maybe you should use {file.uri} anyway.
Why would you change it to {file.documenturi}?

[SoumyBhow]

If what I'm seeing here https://pegasus-frontend.org/docs/user-guide/meta-files/ is right, maybe you should use {file.uri} anyway. Why would you change it to {file.documenturi}?

It's cause before, file.uri was an attempt by the dev to fix launching from emulators that use SAF (like PPSSPP, M64PFZ, etc). However that didn't work well, so the dev implemented the new way as file.documenturi. Also I've already tried file.uri but with no success.

[gtaforever00]

So looking into Pegasus and the issues with MelonDS launching, it seems it's related to how Pegasus encodes the uri. I'm not sure if Pegasus or MelonDS needs changed. It seems Pegasus encodes Unreserved Characters that RFC2396 states the following.

Unreserved characters can be escaped without changing the semantics
   of the URI, but this should not be done unless the URI is being used
   in a context that does not allow the unescaped character to appear.

http://www.faqs.org/rfcs/rfc2396.html

Other emulators seem fine with this so I'm not sure who would need to fix the issue.

TLDR;
Remove any unreserved characters from your file name in Pegasus and rom file and it works.

unreserved characters

"-" | "_" | "." | "!" | "~" | "*" | "'" | "(" | ")"

[ciaskohansen]

Hello, any progress with its use in frontends? I'm on Android 13 and I use Arc Browser and following the last comments there is no way to launch it.