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Simple DirectMedia Layer

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Free software multimedia library

Simple DirectMedia Layer

Original author	Sam Lantinga
Developer	SDL Community
Initial release	1998; 28 years ago (1998)

Stable release	3.4.0^[1] /1 January 2026 2.32.0 / 8 February 2025

Written in	C
Operating system	Version 3 supports same (current) platforms asversion 2, such as 32- and 64-bit Windows XP+ and 64-bit macOS 10.7+(support dropped for outdated e.g. Windows Phone/UWP^[2]).^[3] Support for version 2:Linux (e.g.SteamOS), Windows,macOS 10.4+,iOS 3.1.3+,tvOS,^[4]Android 2.3.3+,FreeBSD 8.4+,Nintendo Switch,PlayStation 2, Haiku,RISC OS 3.5+,^[5]MorphOS 0.4+^[6]^[7] Additionally before v2.0.0: e.g.AmigaOS andMorphOS, and consoles (PlayStation, Xbox, Wii, etc), Nintendo DS
Platform	IA-32 (x86),x86-64,PowerPC,AArch64
Type	API
License	zlib License Before 2.0.0: GNU LGPL^[8]
Website	www.libsdl.org
Repository	github.com/libsdl-org/SDL

Simple DirectMedia Layer (SDL) is across-platform software development library designed to provide ahardware abstraction layer for computermultimedia hardware components. Software developers can use it to write high-performancecomputer games and other multimedia applications that can run on manyoperating systems such asAmigaOS,Android,iOS,Linux,MorphOS,macOS, andWindows.^[9]

SDL managesvideo,audio,input devices,threads,shared object loading,computer networking and timers.^[10] For 3D graphics, it can handle anOpenGL,Vulkan,^[11]Metal, orDirect3D11 (older Direct3D version 9 is also supported) context. A common misconception is that SDL is agame engine. However, the library is suited to building games directly, or is usable indirectly by engines built on top of it.

The library is internally written inC and possibly, depending on the target platform,C++ orObjective-C, and provides theapplication programming interface in C, with bindings to other languages available.^[12] It isfree and open-source software subject to the requirements of thezlib License since version 2.0, and with prior versions subject to theGNU Lesser General Public License.^[8] Under the zlib License, SDL 2.0 is freely available forstatic linking inclosed-source projects, unlike SDL 1.2,^[13] although it is possible for the user to override the statically linked library with one provided by them.^[14] SDL 2.0, released in 2013, was a major departure from previous versions, offering more opportunity for 3D hardware acceleration, but breaking backwards-compatibility; a wrapper library made to translate 1.2 calls to 2.0 was later made available.^[15]

SDL is extensively used in the industry in both large and small projects. By 2010, over 700 games, 180 applications, and 120 demos had been posted on the library website.^[16]

SDL supportsEmscripten (i.e. programs that run on a web page).

SDL 3 was released, as a stable version, in January 2025. It has a migration guide, andCoccinelle tool support to help migrate to the new major version. SDL 3 has a new way to control the entry point of your program,^[17] and you can optionally control execution in a non-framework way.

History

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Sam Lantinga created the library, first releasing it in early 1998, while working forLoki Software. He got the idea while porting a Windows application to Macintosh. He then used SDL to portDoom toBeOS (seeDoom source ports).^[18] Around the time of its creation, SDL was regarded as a simple alternative to DirectX.^[19] Several other free libraries were developed to work alongside SDL, such asSMPEG andOpenAL^[clarify]. He also founded Galaxy Gameworks in 2008 to help commercially support SDL, although the company plans are currently on hold due to time constraints.^[20]

Soon after putting Galaxy Gameworks on hold, Lantinga announced that SDL 1.3 (which would then later become SDL 2.0) would be licensed under thezlib License.^[21] Lantinga announced SDL 2.0 on 14 July 2012, at the same time announcing that he was joiningValve, the first version of which was announced the same day he joined the company.^[22] Lantinga announced the stable release of SDL 2.0.0 on 13 August 2013.^[23]

SDL 2.0 is a major update to the SDL 1.2codebase with a different, notbackwards-compatible^[24]API. It replaces several parts of the 1.2 API with more general support for multiple input and output options. Some feature additions include multiple window support, hardware-accelerated 2D graphics, and betterUnicode support.^[25]

Support forMir andWayland was added in SDL 2.0.2^[26] and enabled by default in SDL 2.0.4.^[27] Version 2.0.4 also provided better support for Android.^[28]

In 2024, the stable preview of SDL 3.1.3 was released (and in January 2025 3.2.0 was released as stable). It makes the API more consistent and allows access to more parts of the device, along with other features.^[29]

Software architecture

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SDL is awrapper around the operating-system-specific functions that the program needs to access. The only purpose of SDL is to provide a common framework for accessing these functions for multiple operating systems (cross-platform).^[30] SDL provides support for 2D pixel operations, sound, file access, event handling, timing and threading. It is often used to complementOpenGL by setting up the graphical output and providing mouse and keyboard input, since OpenGL comprises only rendering.

A game using the Simple DirectMedia Layer willnot automatically run on every operating system; further adaptations must be applied. These are reduced to a minimum, since SDL also contains a few abstraction APIs for frequent functions offered by an operating system.

The syntax of SDL is function-based: all operations done in SDL are done by passing parameters tosubroutines (functions). Special structures are also used to store the specific information SDL needs to handle. SDL functions are categorized under several different subsystems.

Subsystems

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SDL is divided into several subsystems:^[31]

Basics: Initialization and Shutdown, Configuration Variables, Error Handling, Log Handling
Video: Display and Window Management, surface functions, rendering acceleration, etc.
Input Events: Event handling, Support for Keyboard, Mouse, Joystick and Game controller
Force Feedback: SDL_haptic.h implements support for "Force Feedback"
Audio: SDL_audio.h implements Audio Device Management, Playing and Recording
Threads: multi-threading: Thread Management, Thread Synchronization Primitives, Atomic Operations
Timers: Timer Support
File Abstraction: Filesystem Paths, File I/O Abstraction
Shared Object Support: Shared Object Loading and Function Lookup
Platform and CPU Information: Platform Detection, CPU Feature Detection, Byte Order and Byte Swapping, Bit Manipulation
Power Management: Power Management Status
Additional: Platform-specific functionality

Besides this basic, low-level support, there also are a few separate official libraries that provide some more functions. These comprise the "standard library", and are provided on the official website and included in the official documentation:

SDL_image — support for multiple image formats^[32]
SDL_mixer — complex audio functions, mainly for sound mixing^[33]
SDL_net — networking support^[34]
SDL_ttf —TrueType font rendering support^[35]
SDL_rtf — simpleRich Text Format rendering^[36]

Other, non-standard libraries also exist. For example: SDL_Collide on SourceForge created byAmir Taaki.

Language bindings

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The SDL 2.0 library haslanguage bindings for:

Ada^[12]
Beef
C
C++
C#^[12]
Common Lisp^[37]
D^[12]
Erlang
Fortran^[38]
Gambas^[39]
Go^[12]^[40]
Haskell^[41]^[42]
Java (e.g. JSDL)
Julia^[43]^[44]^[45]^[40]
Lua^[12]
Nim^[46]
OCaml^[12]
Pascal^[12]
Perl (via SDL)^[47]
PHP^[48]
Python (several, e.g. pygame_sdl2 and sdl2hl)^[12]
Raku^[49]
Rust^[12]
Vala

Supported back-ends

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Abstraction layers of several SDL platforms

Because of the way SDL is designed, much of its source code is split into separate modules for each operating system, to make calls to the underlying system. When SDL is compiled, the appropriate modules are selected for the target system. The following back-ends are available:^[9]

GDI back-end forMicrosoft Windows.
DirectX back-end; older SDL 1.2 uses DirectX 7 by default, while 2.0 defaults to DirectX 9 and can access up to DirectX 12.
Quartz back-end formacOS (dropped in 2.0).
Metal back-end formacOS /iOS /tvOS since 2.0.8; older versions use OpenGL by default.^[50]^[51]
Xlib back-end forX11-basedwindowing system on various operating systems.^[52]
OpenGL contexts on various platforms.^[53]
EGL back-end when used in conjunction with Wayland-based windowing system.,^[54]Raspberry Pi^[55] and other systems.
Vulkan contexts on platforms that support it.^[11]
sceGu back-end, a Sony OpenGL-like backend native to thePSP.

An unofficialSixel back-end is available for SDL 1.2.^[56]

TheRockbox MP3 player firmware also distributes a version of SDL 1.2, which is used to run games such asQuake.^[57]

Reception and adoption

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Workshop on SDL,University of Cádiz (2010)

Over the years SDL was used for many commercial and non-commercial video game projects. For instance,MobyGames listed 120 games using SDL in 2013,^[58] and the SDL website itself listed around 700 games in 2012.^[59] Important commercial examples areAngry Birds,^[60]Unreal Tournament, and games developed usingValve'sSource Engine, which uses SDL extensively for cross-platform compatibility; ones from the open-source domain areOpenTTD,^[61]The Battle for Wesnoth^[62] orFreeciv.^[63]

The cross-platform game releases of the popularHumble Indie Bundles for Linux, Mac and Android are often SDL-based.

SDL is also often used for later ports on new platforms with legacy code. For instance, the PC gameHomeworld was ported to thePandora handheld^[64] andJagged Alliance 2 for Android^[65] via SDL.

Also, several non video game programs use SDL; examples are theemulators, such asDOSBox,FUSE ZX Spectrum emulator andVisualBoyAdvance.

There were several books written for development with SDL (see further reading).

SDL is used inuniversity courses teaching multimedia andcomputer science, for instance, in a workshop about game programming using libSDL at theUniversity of Cadiz in 2010, or a Game Design discipline atUTFPR (Ponta Grossa campus) in 2015.