Document which drivers people should use.

docs/guides/drivers.md

@@ -1,49 +1,138 @@
-TODO
+Unfortunately,
+there's no standard for
+displaying video,
+playing audio,
+and accepting input from game controllers
+that works on every operating system.
+Or rather,
+there's many standards,
+and different ones work best
+on different computers.
+Therefore,
+higan comes with "drivers"
+for video, audio and input,
+so you can find the one that works best for you.
+To see what drivers you're currently using,
+or to choose different ones,
+go to
+[the Advanced tab](../interface/higan-config.md#Advanced)
+of the Settings window.
 
-Note that when changing a driver,
+Here are the most notable drivers
+for each platform
+for each category.
+If your copy of higan
+includes a driver not listed here,
+it's probably a reasonable choice,
+so try it out and see how you like it.
+
+**Note:** After changing any driver,
 you must restart higan for the change to take effect.
 
+**Note:**
+Video, Audio and Input
+all have a special driver named "None".
+This is a dummy driver that does nothing
+(draws no video,
+plays no audio,
+accepts no input),
+so don't choose it unless you're
+trying to diagnose problems with other drivers.
+
 Video
 -----
 
-TODO
+On Windows:
 
-The best option is "OpenGL"
+  - **OpenGL** is usually the best choice,
-(since it allows you to use
+    since it supports [custom shaders](shaders.md),
-[custom shaders](#installing-custom-shaders)),
+    however it does require support for OpenGL 3.2
-and the safest is "Direct Draw" (for Windows)
+    which excludes some integrated graphics chipsets
-or SDL (for Linux).
+    and old graphics cards.
+  - **Direct3D** is a good choice
+    if OpenGL is unavailable.
+    It also allows
+    [Exclusive fullscreen](../interface/higan-config.md#video),
+    bypassing Windows' desktop compositor.
+  - **GDI** is the safest choice,
+    but performs very poorly at large sizes.
+
+On Linux:
+
+  - **OpenGL** is the best choice,
+    since it's fast
+    and it supports [custom shaders](shaders.md),
+    but requires OpenGL 3.2.
+    You can check what version of OpenGL
+    your system supports by running
+    `glxinfo | grep 'core profile version'`
+    in a terminal.
+  - **XVideo** is also fast,
+    but may be low-quality,
+    and generally only supports the "Blur" shader,
+    not "None".
+  - **XShm** is the safest choice,
+    but performs very poorly at large sizes.
 
 Audio
 -----
 
-TODO
+On Windows:
 
-On Linux,
+  - **ASIO** offers the lowest possible latency,
-"PulseAudioSimple" is the most likely to work.
+    but is the least likely to work on any given computer.
-
+  - **WASAPI** offers low latency,
-On Windows, "DirectSound" is probably what you want.
+    but is only slightly more likely to work.
-"XAudio" targets XAudio 2.7,
+    It also offers
-(the last version to work on Windows 7),
+    [Exclusive Mode](../interface/higan-config.md#audio,
-so it requires the latest (June 2010) version
+    which can improve audio quality and lower latency,
+    but may be better or worse than shared mode
+    in practice.
+  - **XAudio2** is a good choice,
+    but it requires the latest (June 2010) version
     of the [DirectX 9 End-User Runtime][dx9]
     to be installed.
+  - **DirectSound** is the safest choice,
+    and not a bad one.
 
 [dx9]: https://www.microsoft.com/en-us/download/details.aspx?id=35
 
+On Linux:
+
+  - **PulseAudio** or **PulseAudioSimple**
+    are almost certainly the drivers to use,
+    since almost every Linux distribution uses
+    [PulseAudio](https://en.wikipedia.org/wiki/PulseAudio)
+    to manage audio output.
+    The two drivers should behave identically,
+    but some users report one working better than the other.
+  - **ALSA** is a good choice
+    for Linux distributions that do not use PulseAudio.
+    If PulseAudio is running,
+    this will wind up using PulseAudio's ALSA emulation,
+    or failing due to "sound card already in use",
+    unless you use a tool like `pasuspender`.
+  - **OSS** may be useful
+    for non-Linux platforms,
+    or for Linux systems with the third-party OSSv4
+    kernel drivers installed.
+    For most Linux systems,
+    this will use ALSA's OSS emulation,
+    PulseAudio's OSS emulation,
+    or not work at all.
+
 Input
 -----
 
-TODO
-
-On Linux,
-"udev" is the most flexble,
-but requires a modern Linux system,
-while "Xlib" should work on other Unix-like OSs
-but only supports a mouse and keyboard.
-
 On Windows,
-"Windows" is the only input driver available,
+"Windows" is the only driver available,
-and automatically uses RawInput for keyboard/mouse,
+and uses RawInput for keyboard and mouse input,
 XInput for Xbox controllers,
 and DirectInput for other controllers.
+
+On Linux:
+
+  - **udev** supports every input device,
+    but requires a modern Linux system.
+  - **Xlib** is the safest choice,
+    but only supports keyboard and mouse input.