Final merge of Google Summer of Code 2008 work...

Audio Ideas - Resampling and Pitch Shifting
by Aaron Wishnick, mentored by Ryan C. Gordon

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%403165

src/audio/SDL_sysaudio.h

@@ -69,6 +69,15 @@ typedef struct SDL_AudioDriver
 } SDL_AudioDriver;
 
 
+/* Streamer */
+typedef struct
+{
+    Uint8 *buffer;
+    int max_len;                /* the maximum length in bytes */
+    int read_pos, write_pos;    /* the position of the write and read heads in bytes */
+} SDL_AudioStreamer;
+
+
 /* Define the SDL audio driver structure */
 struct SDL_AudioDevice
 {
@@ -81,6 +90,10 @@ struct SDL_AudioDevice
     /* An audio conversion block for audio format emulation */
     SDL_AudioCVT convert;
 
+    /* The streamer, if sample rate conversion necessitates it */
+    int use_streamer;
+    SDL_AudioStreamer streamer;
+
     /* Current state flags */
     int iscapture;
     int enabled;