**Note:** This is a quite technical document intended for those that are interested in compiling EmulationStation from source code, or would like to customize the configuration. If you just want to start using the software, check out the [User Guide](USERGUIDE.md) instead.
EmulationStation-DE is developed and compiled using both Clang/LLVM and GCC on Unix, and GCC (MinGW) on Windows. I'm intending to get Clang/LLVM working on Windows as well.
There are much more details regarding compilers later in this document, so read on!
Any code editor can be used of course, but I recommend [VSCodium](https://vscodium.com) or [VSCode](https://code.visualstudio.com).
The code has a few dependencies. For building, you'll need CMake and development packages for cURL, FreeImage, FreeType, libVLC, pugixml, SDL2 and RapidJSON.
Running multiple compile jobs in parallel is a good thing as it speeds up the build time a lot (scaling almost linearly). Here's an example telling make to run 6 parallel jobs:
It's important to know that this is not only the directory used by the install script, the CMAKE_INSTALL_PREFIX variable also modifies code inside ES used to locate the required program resources. So it's necessary that the install prefix corresponds to the location where the application will actually be installed.
Both Clang/LLVM and GCC work fine for building ES.
I did some small benchmarks comparing Clang to GCC with the ES codebase (as of writing it's year 2020) and it's pretty interesting.
Advantages with Clang (vs GCC):
* 10% smaller binary size for a release build
* 17% smaller binary size for a debug build
* 2% faster compile time for a release build
* 16% faster compile time for a debug build
* 4% faster application startup time for a debug build
Advantage with GCC (vs Clang):
* 1% faster application startup time for a release build
*Release build: Optimizations enabled, debug info disabled, binary stripped.* \
*Debug build: Optimizations disabled, debug info enabled, binary not stripped.*
This Clang debug build is LLVM "native", i.e. intended to be debugged using the LLVM project debugger LLDB. The problem is that this is still not well integrated with VSCodium that I use for development so I need to keep using GDB. But this is problematic as the libstd++ data required by GDB is missing in the binary, making it impossible to see the values of for instance `std::string` variables.
It's possible to activate the additional debug info needed by GDB by using the flag `-D_GLIBCXX_DEBUG`. I've added this to CMakeLists.txt when using Clang, but this bloats the binary and makes the code much slower. Actually, instead of a 4% faster application startup, it's now 36% slower! The same goes for the binary size, instead of 17% smaller it's now 17% larger.
I'm expecting this to be resolved in the near future though, and as I think Clang is an interesting compiler, I use it as the default when working on the project (I sometimes test with GCC to make sure that it still builds the software correctly).
The theme is not mandatory to start the application, but ES will be basically useless without it.
So the home directory will always take precedence, and any resources or themes located there will override the ones in the installation path or the path of the ES executable.
I did a brief evaluation of the Microsoft Visual C++ compiler (MSVC) but as far as I'm concerned it's an abomination so I won't cover it here and it won't be supported.
Make a copy of `mingw64/bin/mingw32-make` to `make` just for convenience and make sure that the necessary paths are defined for the PATH environmental variable.
I won't get into the details on how to configure Git, but there are many resources available online to support with this. The `Git Bash` shell is very useful though as it's somewhat reproducing a Unix environment using MinGW/MSYS.
Install your editor of choice. As for VSCodium it's unfortunately broken or crippled under Windows, making some important extensions impossible to install. VSCode can however be used instead.
It's strongly recommended to set line breaks to Unix-style (linefeed only) directly in the editor, although it can also be configured in Git for conversion during commit. The source code for EmulationStation-DE only uses Unix-style line breaks.
Note that most GDB builds for Windows have broken Python support so that pretty printing won't work. The MinGW installation recommended in the previous step works fine though.
As there is no standardized include directory structure in Windows and no package manager, you need to provide the include files manually.
Make a directory in your build environment tree, for instance under `C:/Programming/include`.
Copy the include files from cURL, FreeImage, FreeType, pugixml, RapidJSON, SDL2 and VLC to this directory.
It should then look something like this:
```
$ ls -1 include/
curl/
FreeImage.h
freetype/
ft2build.h
pugiconfig.hpp
pugixml.hpp
rapidjson/
SDL2/
vlc/
```
**Copy the required DLL files to the EmulationStation build directory:**
As there's no package manager in Windows and no way to handle dependencies, we need to ship all the required shared libraries with the application.
Copy the following files to the `emulationstation-de` build directory. Most of them will come from the packages that were provided in the previous steps of this guide:
```
FreeImage.dll
libcrypto-1_1-x64.dll (from the OpenSSL package, located in Git MinGW/MSYS under /mingw/bin/)
libcurl-x64.dll
libfreetype.dll
libgcc_s_seh-1.dll (located in Git MinGW/MSYS under /mingw/bin/)
libpugixml.dll
libssl-1_1-x64.dll (from the OpenSSL package, located in Git MinGW under /mingw/bin/)
libstdc++-6.dll
libvlc.dll
libvlccore.dll
libwinpthread-1.dll (located in Git MinGW under /mingw/bin/)
SDL2.dll
libSDL2main.a
```
The files from the MinGW installation must correspond to the version used to compile the binary.
*So if the MinGW installation is upgraded to a newer version or so, make sure to copy the .dll files again, overwriting the old ones.*
In addition to these, you need to copy some libraries from the VLC `plugins` folder to be able to play video files. There is a subdirectory structure under the plugins folder and although there is no requirement to retain these as libVLC apparently looks recursively for the required .dll files, it still makes it a bit more tidy to keep the folder names for each type of plugin. The CMake install script will however copy all the contents of this plugins folder regardless of whether subdirectories are in use or not.
It's a bit tricky to know which libraries are really needed. But as the plugins directory is around 120 MB (as of VLC version 3.0.11), we definitely only want to copy the files we need.
The following files seem to be required to play most video and audio formats (place them in `emulationstation-de\plugins\`):
For some reason defining the '../include' path doesn't work when running CMake from PowerShell (and no, changing to backslash doesn't help). Instead use Bash, by running from a `Git Bash` shell.
The make command works fine directly in PowerShell though so it can be run from the VSCode terminal.
Running `make -j6` (or whatever number of parallel jobs you prefer) should now build the binary.
Note that compilation time is much longer than on Unix, and linking time is excessive for a debug build. The debug binary is also much larger than on Unix.
A worthwhile endeavour could be to setup a cross-compilation environment using WLS/WLS2 (Linux), but I have not tried it.
The default installation directory suggested by the installer is `C:\Program Files\EmulationStation`. However this can of course be changed by the user.
ES will look in the following locations for the resources, in the listed order:
*`[HOME]\.emulationstation\resources\`
*`[ES EXECUTABLE DIRECTORY]\resources\`
**Note:** The resources directory is critical, without it the application won't start.
And it will look in the following locations for the themes, also in the listed order:
*`[HOME]\.emulationstation\themes\`
*`[ES EXECUTABLE DIRECTORY]\themes\`
The theme is not mandatory to start the application, but ES will be basically useless without it.
So the home directory will always take precedence, and any resources or themes located there will override the ones in the path of the ES executable.
The contents of f:\ should now look something like this:
```
EmulationStation
ES-Home
RetroArch
start_es.bat
```
Now run the batch script, ES should start and ask you to configure any attached controllers. Following this, check that everything works as expected, i.e. the gamelists are properly populated etc.
You can optionally skip the configuration of the controllers by copying any existing `es_input.cfg` file to `f:\ES-Home\.emulationstation\es_input.cfg`.
Exit ES and modify the file `f:\ES-Home\.emulationstation\es_systems.cfg` to point to the emulators on the portable media.
EmulationStation Desktop Edition ships with a comprehensive `es_systems.cfg` configuration file, and as the logic is to use a `%ROMPATH%` variable to locate the ROM files (with a corresponding setting in `es_settings.cfg`), normally you shouldn't need to modify this file to the same extent as previous versions of EmulationStation. Still, see below in this document on how to adjust the es_systems.cfg file if required.
Upon first startup of the application, if there is no es_systems.cfg file present, it will be copied from the template subdirectory inside the resources directory. This directory is located in the installation path of the application, for instance `/usr/local/share/emulationstation/resources/templates`.
This file contains all the settings supported by ES, at their default values. Normally you shouldn't need to modify this file manually, instead you should be able to use the menu inside ES to update all the necessary settings.
The exception would be the ROMDirectory setting as ES won't start if no ROM files are found.
By default, ES looks in `~/ROMs` for the ROM files, where they are expected to be grouped into directories corresponding to the game systems, for example:
Keep in mind though that you still need to group the ROMs into directories corresponding to the platform names in es_systems.cfg.
There is also support to add the variable %ESPATH% to the ROM directory setting, this will expand to the path where the ES executable is started from. This is useful for a portable emulator installation, for example on a USB memory stick.
When you first start EmulationStation, you will be prompted to configure an input device. The process is thus:
1. Hold a button on the device you want to configure. This includes the keyboard.
2. Press the buttons as they appear in the list. Some inputs can be skipped by holding any button down for a few seconds (e.g. page up/page down).
3. You can review your mappings by pressing up and down, making any changes by pressing A.
4. Choose "SAVE" to save this device and close the input configuration screen.
The new configuration will be added to the `~/.emulationstation/es_input.cfg` file.
**Both new and old devices can be (re)configured at any time by pressing the Start button and choosing "CONFIGURE INPUT".** From here, you may unplug the device you used to open the menu and plug in a new one, if necessary. New devices will be appended to the existing input configuration file, so your old devices will retain their configuration.
**If your controller stops working, you can delete the `~/.emulationstation/es_input.cfg` file to make the input configuration screen re-appear on the next run.**
As you can see above, you can override the home directory path using the `--home` flag. So by running for instance the command `emulationstation --home ~/games/emulation`, ES will use `~/games/emulation/.emulationstation` as its base directory.
The order EmulationStation displays systems reflects the order you define them in. In the case of the default es_systems.cfg file, the systems are listed in alphabetical order.
**Note:** A system *must* have at least one game present in its `path` directory, or ES will ignore it! If no valid systems are found, ES will report an error and quit.
`%BASENAME%` - Replaced with the "base" name of the path to the selected ROM. For example, a path of `/foo/bar.rom`, this tag would be `bar`. This tag is useful for setting up AdvanceMAME.
`%ROM_RAW%` - Replaced with the unescaped, absolute path to the selected ROM. If your emulator is picky about paths, you might want to use this instead of %ROM%, but enclosed in quotes.
`%EMUPATH%` - Replaced with the path to the emulator binary. This is expanded either using the PATH environmental variable of the operating system, or if an absolute emulator path is defined, this will be used instead. This variable is mostly useful to define the emulator core path for Windows, as this operating system does not have a standardized program installation directory structure.
`%ESPATH%` - Replaced with the path to the EmulationStation binary. Mostly useful for portable emulator installations, for example on a USB memory stick.
As of the fork to EmulationStation Desktop Edition, game media information no longer needs to be defined in the gamelist.xml files. Instead the application will look for any media matching the ROM filename. The media path where to look for game art is configurable either manually in `es_settings.cfg` or via the GUI. If configured manually in es_settings.cfg, it looks something like this:
You can use ES's [scraping](http://en.wikipedia.org/wiki/Web_scraping) tools to populate the gamelist.xml files. There are two ways to run the scraper:
* **If you want to scrape multiple games:** press the Start button to open the menu and choose the "SCRAPER" option. Adjust your settings and press "START".
* **If you just want to scrape one game:** find the game on the game list in ES and press the Select button. Choose "EDIT THIS GAME'S METADATA" and then press the "SCRAPE" button at the bottom of the metadata editor.
You can also edit metadata within ES by using the metadata editor - just find the game you wish to edit on the gamelist, press Select, and choose "EDIT THIS GAME'S METADATA."
The home directory can be overridden using the `--home` option from the command line, see above in this document for details regarding that.
An example gamelist.xml:
```xml
<gameList>
<game>
<path>./mm2.nes</path>
<name>Mega Man 2</name>
<desc>Mega Man 2 is a classic NES game which follows Mega Man as he murders eight robot masters in cold blood.</desc>
</game>
</gameList>
```
Everything is enclosed in a `<gameList>` tag. The information for each game or folder is enclosed in a corresponding tag (`<game>` or `<folder>`). Each piece of metadata is encoded as a string.
**gamelist.xml reference:**
There are a few types of metadata:
*`string` - just text.
*`float` - a floating-point decimal value (written as a string).
*`integer` - an integer value (written as a string).
*`datetime` - a date and, potentially, a time. These are encoded as an ISO string, in the following format: "%Y%m%dT%H%M%S%F%q". For example, the release date for Chrono Trigger is encoded as "19950311T000000" (no time specified).
Some metadata is also marked as "statistic" - these are kept track of by ES and do not show up in the metadata editor. They are shown in certain views (for example, the detailed view and the video view both show `lastplayed`, although the label can be disabled by the theme).
#### `<game>`
*`name` - string, the displayed name for the game.
*`desc` - string, a description of the game. Longer descriptions will automatically scroll, so don't worry about size.
*`rating` - float, the rating for the game, expressed as a floating point number between 0 and 1. ES will round fractional values to half-stars.
*`releasedate` - datetime, the date the game was released. Displayed as date only, time is ignored.
*`developer` - string, the developer for the game.
*`publisher` - string, the publisher for the game.
*`genre` - string, the (primary) genre for the game.
*`players` - integer, the number of players the game supports.
*`favorite` - bool, indicates whether the game is a favorite.
*`completed`- bool, indicates whether the game has been completed.
*`broken` - bool, indicates a game that doesn't work (useful for MAME).
*`kidgame` - bool, indicates whether the game is suitable for children, used by the `kid' UI mode.
*`playcount` - integer, the number of times this game has been played.
*`lastplayed` - statistic, datetime, the last date and time this game was played.
*`sortname` - string, used in sorting the gamelist in a system, instead of `name`.
*`launchcommand` - optional tag that is used to override the emulator and core settings on a per-game basis.
* If a value matches the default for a particular piece of metadata, ES will not write it to the gamelist.xml (for example, if `genre` isn't specified, ES won't write an empty genre tag)
