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diff --git a/src/engine/external/portaudio/pa_dither.c b/src/engine/external/portaudio/pa_dither.c
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+/*
+ * $Id: pa_dither.c 1097 2006-08-26 08:27:53Z rossb $
+ * Portable Audio I/O Library triangular dither generator
+ *
+ * Based on the Open Source API proposed by Ross Bencina
+ * Copyright (c) 1999-2002 Phil Burk, Ross Bencina
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+ * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * The text above constitutes the entire PortAudio license; however, 
+ * the PortAudio community also makes the following non-binding requests:
+ *
+ * Any person wishing to distribute modifications to the Software is
+ * requested to send the modifications to the original developer so that
+ * they can be incorporated into the canonical version. It is also 
+ * requested that these non-binding requests be included along with the 
+ * license above.
+ */
+
+/** @file
+ @ingroup common_src
+
+ @brief Functions for generating dither noise
+*/
+
+
+#include "pa_dither.h"
+#include "pa_types.h"
+
+#define PA_DITHER_BITS_   (15)
+
+
+void PaUtil_InitializeTriangularDitherState( PaUtilTriangularDitherGenerator *state )
+{
+    state->previous = 0;
+    state->randSeed1 = 22222;
+    state->randSeed2 = 5555555;
+}
+
+
+signed long PaUtil_Generate16BitTriangularDither( PaUtilTriangularDitherGenerator *state )
+{
+    signed long current, highPass;
+
+    /* Generate two random numbers. */
+    state->randSeed1 = (state->randSeed1 * 196314165) + 907633515;
+    state->randSeed2 = (state->randSeed2 * 196314165) + 907633515;
+
+    /* Generate triangular distribution about 0.
+     * Shift before adding to prevent overflow which would skew the distribution.
+     * Also shift an extra bit for the high pass filter. 
+     */
+#define DITHER_SHIFT_  ((SIZEOF_LONG*8 - PA_DITHER_BITS_) + 1)
+    current = (((signed long)state->randSeed1)>>DITHER_SHIFT_) +
+              (((signed long)state->randSeed2)>>DITHER_SHIFT_);
+
+    /* High pass filter to reduce audibility. */
+    highPass = current - state->previous;
+    state->previous = current;
+    return highPass;
+}
+
+
+/* Multiply by PA_FLOAT_DITHER_SCALE_ to get a float between -2.0 and +1.99999 */
+#define PA_FLOAT_DITHER_SCALE_  (1.0f / ((1<<PA_DITHER_BITS_)-1))
+static const float const_float_dither_scale_ = PA_FLOAT_DITHER_SCALE_;
+
+float PaUtil_GenerateFloatTriangularDither( PaUtilTriangularDitherGenerator *state )
+{
+    signed long current, highPass;
+
+    /* Generate two random numbers. */
+    state->randSeed1 = (state->randSeed1 * 196314165) + 907633515;
+    state->randSeed2 = (state->randSeed2 * 196314165) + 907633515;
+
+    /* Generate triangular distribution about 0.
+     * Shift before adding to prevent overflow which would skew the distribution.
+     * Also shift an extra bit for the high pass filter. 
+     */
+#define DITHER_SHIFT_  ((SIZEOF_LONG*8 - PA_DITHER_BITS_) + 1)
+    current = (((signed long)state->randSeed1)>>DITHER_SHIFT_) +
+              (((signed long)state->randSeed2)>>DITHER_SHIFT_);
+
+    /* High pass filter to reduce audibility. */
+    highPass = current - state->previous;
+    state->previous = current;
+    return ((float)highPass) * const_float_dither_scale_;
+}
+
+
+/*
+The following alternate dither algorithms (from musicdsp.org) could be
+considered
+*/
+
+/*Noise shaped dither  (March 2000)
+-------------------
+
+This is a simple implementation of highpass triangular-PDF dither with
+2nd-order noise shaping, for use when truncating floating point audio
+data to fixed point.
+
+The noise shaping lowers the noise floor by 11dB below 5kHz (@ 44100Hz
+sample rate) compared to triangular-PDF dither. The code below assumes
+input data is in the range +1 to -1 and doesn't check for overloads!
+
+To save time when generating dither for multiple channels you can do
+things like this:  r3=(r1 & 0x7F)<<8; instead of calling rand() again.
+
+
+
+  int   r1, r2;                //rectangular-PDF random numbers
+  float s1, s2;                //error feedback buffers
+  float s = 0.5f;              //set to 0.0f for no noise shaping
+  float w = pow(2.0,bits-1);   //word length (usually bits=16)
+  float wi= 1.0f/w;            
+  float d = wi / RAND_MAX;     //dither amplitude (2 lsb)
+  float o = wi * 0.5f;         //remove dc offset
+  float in, tmp;
+  int   out;
+
+
+//for each sample...
+
+  r2=r1;                               //can make HP-TRI dither by
+  r1=rand();                           //subtracting previous rand()
+    
+  in += s * (s1 + s1 - s2);            //error feedback
+  tmp = in + o + d * (float)(r1 - r2); //dc offset and dither 
+  
+  out = (int)(w * tmp);                //truncate downwards
+  if(tmp<0.0f) out--;                  //this is faster than floor()
+
+  s2 = s1;                            
+  s1 = in - wi * (float)out;           //error
+
+
+
+-- 
+paul.kellett@maxim.abel.co.uk
+http://www.maxim.abel.co.uk
+*/
+
+
+/*
+16-to-8-bit first-order dither
+
+Type : First order error feedforward dithering code
+References : Posted by Jon Watte
+
+Notes : 
+This is about as simple a dithering algorithm as you can implement, but it's
+likely to sound better than just truncating to N bits.
+
+Note that you might not want to carry forward the full difference for infinity.
+It's probably likely that the worst performance hit comes from the saturation
+conditionals, which can be avoided with appropriate instructions on many DSPs
+and integer SIMD type instructions, or CMOV.
+
+Last, if sound quality is paramount (such as when going from > 16 bits to 16
+bits) you probably want to use a higher-order dither function found elsewhere
+on this site. 
+
+
+Code : 
+// This code will down-convert and dither a 16-bit signed short 
+// mono signal into an 8-bit unsigned char signal, using a first 
+// order forward-feeding error term dither. 
+
+#define uchar unsigned char 
+
+void dither_one_channel_16_to_8( short * input, uchar * output, int count, int * memory ) 
+{ 
+  int m = *memory; 
+  while( count-- > 0 ) { 
+    int i = *input++; 
+    i += m; 
+    int j = i + 32768 - 128; 
+    uchar o; 
+    if( j < 0 ) { 
+      o = 0; 
+    } 
+    else if( j > 65535 ) { 
+      o = 255; 
+    } 
+    else { 
+      o = (uchar)((j>>8)&0xff); 
+    } 
+    m = ((j-32768+128)-i); 
+    *output++ = o; 
+  } 
+  *memory = m; 
+} 
+*/