First shot at new audio resampling code.

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%403483

include/SDL_audio.h

@@ -147,15 +147,10 @@ typedef struct SDL_AudioCVT
     SDL_AudioFormat dst_format; /* Target audio format */
     double rate_incr;           /* Rate conversion increment */
     Uint8 *buf;                 /* Buffer to hold entire audio data */
-    Uint8 *coeff;               /* Filter coefficients: either big windowed sinc filter, or 6 IIR lowpass coefficients */
-    Uint8 *state_buf;           /* Sample history for either the FIR or IIR filter. For IIR filter, first two elements are X, second two are Y, and state_pos toggles the order */
-    int state_pos;              /* Position in the state */
-    int len_sinc;               /* Length of windowed sinc filter, in appropriate units (not necessarily bytes) */
     int len;                    /* Length of original audio buffer */
     int len_cvt;                /* Length of converted audio buffer */
     int len_mult;               /* buffer must be len*len_mult big */
-    int len_div;                /* destination length = len_mult / len_div * src length */
-    double len_ratio;           /* Given len, final size is len*len_ratio ( len_ratio = len_mult / len_div ) */
+    double len_ratio;           /* Given len, final size is len*len_ratio */
     SDL_AudioFilter filters[10];        /* Filter list */
     int filter_index;           /* Current audio conversion function */
 } SDL_AudioCVT;

src/audio/SDL_audio.c

@@ -371,6 +371,7 @@ SDL_RunAudio(void *devicep)
             silence = 0;
         }
 
+#if 0  /* !!! FIXME: I took len_div out of the structure. Use rate_incr instead? */
         /* If the result of the conversion alters the length, i.e. resampling is being used, use the streamer */
         if (device->convert.len_mult != 1 || device->convert.len_div != 1) {
             /* The streamer's maximum length should be twice whichever is larger: spec.size or len_cvt */
@@ -391,6 +392,7 @@ SDL_RunAudio(void *devicep)
                 device->spec.size * device->convert.len_div /
                 device->convert.len_mult;
         }
+#endif
 
         /* stream_len = device->convert.len; */
         stream_len = device->spec.size;

src/audio/SDL_audio_c.h

@@ -42,4 +42,15 @@ typedef struct
 } SDL_AudioTypeFilters;
 extern const SDL_AudioTypeFilters sdl_audio_type_filters[];
 
+/* this is used internally to access some autogenerated code. */
+typedef struct
+{
+    SDL_AudioFormat fmt;
+    int channels;
+    int upsample;
+    int multiple;
+    SDL_AudioFilter filter;
+} SDL_AudioRateFilters;
+extern const SDL_AudioRateFilters sdl_audio_rate_filters[];
+
 /* vi: set ts=4 sw=4 expandtab: */