nton/README.md

NTON

Nintendo Switch NRO to NSP Forwarder for firmware 12.0.0 and newer.

A forwarder lets you open a Homebrew NRO file from your SD card through the Nintendo Switch Home Screen instead of the Homebrew Launcher.

This is more so a script for making NSPs using mpham's original Forwarder ROM here. My script is specifically aimed toward general homebrew NRO forwarding, not Retroarch Game Forwarding.

The goal with my version is to automate as much as can be automated. Especially the annoying icons. There's still some work to be done to finalize automation as the goal is to only need to provide a path to the NRO that's on your switch's microSD card.

Changes

1. The script was rewritten almost entirely.
2. NSPs now save to /output and are named to be more human-readable.
3. control.nacp and the icon_AmericanEnglish.dat icon file are now automatically extracted from the NRO.
4. The icon_AmericanEnglish.dat is now automatically re-formatted as JPEG and re-stripped where necessary. Even though it's extracted from the NRO, it still does this. Not all NRO icon dat files are up to spec for NSPs.
5. You now specify the publisher when calling build.
6. The path to the NRO must exist for automation to work. The best way is to insert your Switch's microSD card and specify the drive letter for it in the call.

Installation

1. Download the project and extract it.
2. Install the latest ImageMagick release. I recommend via winget or chocolatey.
3. Download the latest hacBrewPack and nstool binaries and place them within the root of the project folder.
4. Place your prod.keys at the root of the project folder. Make sure it's up to date for the firmware version you're switch is on. You can get this file using Lockpick_RCM.

Usage

build "<Name>" "<Publisher>" "<Drive Letter>" "<Path to NRO>" ["<Title ID>"]

• I recommend wrapping all arguments with "..." like shown in case they have special characters.
• The Path to the NRO must start with / exactly. Not a \ nor C:\ or C:/.
• The Drive Letter must only be the letter, e.g., D, not D:/ or D:\ or D:.
• The Title ID argument is entirely optional and a random Title ID will be generated if one is not specified.

For example, to make a forwarder for the Homebrew Menu that's on your Switch's microSD at D:\hbmenu.nro,

build "Homebrew Menu" "switchbrew" "D" "/hbmenu.nro"

To-do

• Combine the Drive letter and Path arguments and manually split them when they need to be separate instead.
• Automate name and publisher by extracting from the extracted control.nacp.
• Force disable save data allocation. Fixed in v3.3.5 of Nro2NSP.
• Force enabling recording by editing the NROs extracted control.nacp at offset 0x3035 from 0 to 2 (forced). Forced is a lot better than 1 (manual) as it allows the video to be saved. A way to enable screenshots should be done as well. SAK has a way to do this.
• Add support for direct RetroArch Game Forwarding.
• Rewrite as a Python script to heavily improve the user experience and code.
• Maybe a new GUI one day, and let you override the icons and such?

Issues

The following are known issues with the original forwarder ROM and are currently out-of-scope of this project.

• Pressing + or using such actions to exit NROs fail. On my end, it reopens the NRO but some have crashes instead.

Troubleshooting

Before continuing try running the homebrew from the Homebrew Launcher and see if it works through there. If it does not work through the Homebrew launcher either, then it was never the forwarder's fault and you should check on your NRO or application installation.

Please note that using Forwarders others have created has a good chance of not working on your system. The location of the NRO on their system may differ from the location on your system, hence the NSP won't be able to load the homebrew.

The forwarder does not launch, "The software was closed because an error occurred."

You're sigpatches that allow non-signed software to launch is outdated or not set up correctly. The prod.keys you used to create the NSP may also be outdated. Get new ones with Lockpick_RCM and make sure you choose to get keys from whichever SysNAND or EmuNAND is actually on the latest firmware.

The forwarder starts loading but then crashes

If it gets to the black loading screen with the Nintendo Switch logo, but then crashes, you may be setting the NRO path wrong when making the NSP. Make sure it starts with / and is an absolute path to an existing NRO file on your Switch's microSD card. The path you built for must be where the NRO file lies in your Switch's microSD card, not your PC.

The forwarder's icon is a '?'

The icon_AmericanEnglish.dat is not to the spec that Nintendo likes in some way. This is usually caused by the format of the image not being a JPEG, or it has EXIF data or an embedded color space.

I recommend stripping all EXIF metadata and saving without an Embed Color Space. You can do this quickly with ImageMagick, magick mogrify -format jpg -resize 256x256 -strip "C:\Users\John\Downloads\icon.png".

The forwarder randomly stopped working after a while, I changed nothing!

You most likely updated your Switch's Firmware and need to update your sigpatches. If not, you may have deleted the NRO from your Switch's microSD card or moved the NRO somewhere else. It cannot be moved as the built NSP loads the NRO at the specified path when you ran build.

It's also possible the firmware update has broken the forwarder ROM that is used and needs to be fixed. Firmware 9.0.0 and 12.0.0 are times the firmware has broken different forwarder ROMs in the past.

Credit

• mpham for the original v12.0.0+ forwarder ROM and original batch script.

• meliodas2255 for recompiling the forwarder ROM for the latest hbl-loader as of May 2021 supporting RetroArch Forwarders and general Homebrew.

License

[GNU General Public License, Version 3.0][LICENSE]