Simple DirectMedia Layer (SDL) is a cross-platform software development library designed to provide a hardware abstraction layer for computer multimedia hardware components. Software developers can use it to write high-performance computer games and other multimedia applications that can run on many operating systems such as Android, iOS, Linux, macOS, and Windows.
SDL manages video, audio, input devices, CD-ROM, threads, shared object loading, networking, and timers. For 3D graphics, it can handle an OpenGL, Vulkan, or Direct3D context. A common misconception is that SDL is a game engine, but this is not true. 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 in C and possibly, depending on the target platform, C++ or Objective-C, and provides the application programming interface in C, with bindings to other languages available. It is free and open-source software subject to the requirements of the zlib License since version 2.0, and with prior versions subject to the GNU Lesser General Public License. Under the zlib License, SDL 2.0 is freely available for static linking in closed-source projects, unlike SDL 1.2.
SDL is extensively used in the industry in both large and small projects. Over 700 games, 180 applications, and 120 demos have been posted on the library website.
Sam Lantinga created the library, first releasing it in early 1998 while working for Loki Software. He got the idea while porting a Windows application to Macintosh. He then used SDL to port Doom to BeOS (see Doom source ports). Several other free libraries were developed to work alongside SDL, such as SMPEG and OpenAL. He also founded Galaxy Gameworks in 2008 to help commercially support SDL, although the company plans are currently on hold due to time constraints. 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 the zlib License. Lantinga announced SDL 2.0 on 14 July 2012, at the same time announcing that he was joining Valve, the first version of which was announced the same day he joined the company. Lantinga announced the stable release of SDL 2.0.0 on 13 August 2013.
SDL 2.0 is a major update to the SDL 1.2 codebase with a different, not backward-compatible 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 better Unicode support.
Support for Mir and Wayland was added in SDL 2.0.2 and enabled by default in SDL 2.0.4.
Version 2.0.4 also provided better support for Android.