Direct3D D3DX DLLs
Windows XP users who keep their machines up to date should all have DirectX 9.0c installed and likewise Vista uses will have DirectX 10 and Windows 7 users DirectX 11. However the D3DX dlls (and sometimes others like XAudio) get updated every few months (when a new SDK is released) and so many users get errors about missing d3dx9_xx.dll. The best solution is to distribute the DirectX runtime with your app. however if you are providing your app. as a download this will increase the download size significantly. You could also of course just include the dll. although this is against the agreement (EULA) and make cause problems. Another solution is to forward users to the Microsoft DirectX end user runtime download via the Microsoft Web Installer.
Download the missing DLLs
Note: these installers will not install DirectX 9.0c, they will only install the missing dlls from the SDK updates. Most people should have DirectX 9.0c as part of Windows XP SP2 but if you do not you can get it via the online Microsoft update page here: Microsoft Web Installer
Note: if you are missing d3dx9d_xx.dll files e.g. d3dx9d_41.dll these files are debug versions of the libraries for development purposes only. Nobody should be distributing these in an application. To use these you need the full developers DirectX SDK.
What the files are
- The d3dx9_?.dll files are for the Direct3D Extensions (D3DX) for Direct3D 9. These provide helper functions for graphic code.
- The d3dx10 dlls are Vista dlls for Direct3D 11.
- The d3dx11 dlls are Windows 7 dlls for Direct3D 11
- The xinput dlls are for the Microsoft common controller library and are used for things like the Xbox 360 common controller.
- XAudio2 is the low level audio API for Windows and Xbox 360
- XACT (XactEngine) is the Microsoft Cross-Platform Audio Creation Tool. This is the high level tool for sound designers.
- X3DAudio is an API that works with XAudio2 and XACT to position sounds in 3D space
- XAPO provides digital signal processing operations on audio streams (working with XAudio2 and XACT) e.g. adding reverb