Overview

This is the source code of Multiness, a NES emulator supporting online multiplayer, which first created in 2016: https://lehoangquyenblog.wordpress.com/published-games/74-2/

This project is a fork of the original Nestopia source code, plus Android (main focus), MacOS, WinRT & iOS port. The purpose of the project is to enhance the original, adding Online multiplayer features.

I created this software a long time ago to play online with my oversea friend. Some of the code are quite hackish, because I had to quickly experiemnt the best possible solution for the network lags, so please don't mind them. And if you can, clean them up if you want. Some of the multiplayer handling code should be in a dedicated file. But currently, I put them in source/core/NstMachine.cpp which might look messy.

Notes:

• Only Android is actively maintained currently. Restrictions Apple & Microsoft put on their respective platforms discourage me from continuing support them. So expect iOS, WinRT projects to be broken in latest revision of the code.
• To build Android app:
  • Run git submodule update --init --recursive before building.
  • Open projects/android in Android Studio.
• Prerequisites for building OSX/iOS version:
  • automake, autoconf, pkgconfig, libtool.
  • run init_thirdparty.sh script.

Multiplayer mechanisms:

• The core mechanism of multiplayer feature is actually very close to video streaming. The host player will render a frame and stream it to 2nd player.
• Pairing people online is done by Google Play Game Services or Facebook invite system.
• Note that Google Play Game Services can connect two 2 people p2p on its own but I didn't use it because the overhead is too high. It has to convert C packet to java byte array before sending out.
• So the p2p connection will be handled by RakNet, it will perform NAT punchthrough technique (this requires dediced server on the cloud) to find the public IP of 2 players and connect them.
• I didn't use any standard video codec in the industry. Instead I defined my own streaming method and compression which currently work fine for this emulator.
• The simple overview of this streaming method:
  • Frame is sent out as key frame at the start of each defined interval.
  • Each key frame uses indexed colors. The most frequently used colors will be assigned smaller indices. So that the compressed frame will use less overall bits (this is byte level compression, i.e. one color index might use less than 8 bits).
  • Within each interval, compress and send out only the deltas between current frame and a key frame before it.
  • The system will detect the network condition and attempt to reduce the framerate/resolution of streaming if the condition is poor and try to increase framerate/resolution back to normal if the condition is good enough. The adaptive dynamic resolution mechanism was not working well in practice. It has been removed. The current mechanism is actually measuring the bandwidth at the start of the game, and adjust the framerate and resolution accordingly. The framerate and resolution once adjusted, won't change during the gameplay.

License

• Multiness: This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. Note that assets & resources files are not covered by this license, see Assets section below.
• Nestopia core: See AUTHORS for list of authors. Can be redistributed and/or modified under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.
• RakNet: (c) 2014, Oculus VR, Inc. BSD License.
• miniupnp: (c) 2005-2017, Thomas BERNARD. BSD License.

Assets

Multiness's icon and onscreen buttons

Images are distributed under the Creative Commons Attribution-NonCommercial 4.0 International license.
Copyright held by Le Hoang Quyen.

The images are included in:

• projects/android/feature_graphics2.xcf
• projects/android/app/src/main/assets/*.png
• projects/android/app/src/main/res/mipmap-*/ic_launcher.png
• projects/android/app/src/gpg/res/mipmap-*/ic_launcher.png
• raw_resources/icon.xcf
• raw_resources/icon_gpg.xcf
• raw_resources/buttons.xcf
• raw_resources/dpad.xcf
• raw_resources/dpad_highlight.xcf
• raw_resources/start_select.xcf
• raw_resources/start_select2.xcf

Other assets

• Original NES controller icon: Thanks to Ryan Dardis and Creative Stall from the Noun Project. Creative Commons Attribution 3.0 license.
• Donation, World and LAN icons: Designed by Freepik and distributed by Flaticon. Flaticon basic license.
• Material Design Icons: from Google's https://material.io/tools/icons/?style=baseline. Licensed under Apache License 2.0.

If you like this project. You can do it via Paypal.