Updated documentation, you don't need to initialize the audio subsystem to do in-place format conversion. (Thanks Simon Hug!)
diff --git a/include/SDL_audio.h b/include/SDL_audio.h
index 24c3df5..53277cb 100644
--- a/include/SDL_audio.h
+++ b/include/SDL_audio.h
@@ -451,7 +451,6 @@ extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 * audio_buf);
* and rate, and initializes the \c cvt structure with information needed
* by SDL_ConvertAudio() to convert a buffer of audio data from one format
* to the other. An unsupported format causes an error and -1 will be returned.
- * The audio subsystem must be initialized before calling this function.
*
* \return 0 if no conversion is needed, 1 if the audio filter is set up,
* or -1 on error.