Initial revision

Originally committed as revision 5 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 120 insertions, 0 deletions

diff --git a/libavcodec/fdctref.c b/libavcodec/fdctref.c
new file mode 100644
index 0000000000..5038e67538
--- /dev/null
+++ b/libavcodec/fdctref.c
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+/* fdctref.c, forward discrete cosine transform, double precision           */
+
+/* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */
+
+/*
+ * Disclaimer of Warranty
+ *
+ * These software programs are available to the user without any license fee or
+ * royalty on an "as is" basis.  The MPEG Software Simulation Group disclaims
+ * any and all warranties, whether express, implied, or statuary, including any
+ * implied warranties or merchantability or of fitness for a particular
+ * purpose.  In no event shall the copyright-holder be liable for any
+ * incidental, punitive, or consequential damages of any kind whatsoever
+ * arising from the use of these programs.
+ *
+ * This disclaimer of warranty extends to the user of these programs and user's
+ * customers, employees, agents, transferees, successors, and assigns.
+ *
+ * The MPEG Software Simulation Group does not represent or warrant that the
+ * programs furnished hereunder are free of infringement of any third-party
+ * patents.
+ *
+ * Commercial implementations of MPEG-1 and MPEG-2 video, including shareware,
+ * are subject to royalty fees to patent holders.  Many of these patents are
+ * general enough such that they are unavoidable regardless of implementation
+ * design.
+ *
+ */
+
+#include <math.h>
+
+// #include "config.h"
+
+#ifndef PI
+# ifdef M_PI
+#  define PI M_PI
+# else
+#  define PI 3.14159265358979323846
+# endif
+#endif
+
+/* global declarations */
+void init_fdct (void);
+void fdct (short *block);
+
+/* private data */
+static double c[8][8]; /* transform coefficients */
+
+void init_fdct()
+{
+  int i, j;
+  double s;
+
+  for (i=0; i<8; i++)
+  {
+    s = (i==0) ? sqrt(0.125) : 0.5;
+
+    for (j=0; j<8; j++)
+      c[i][j] = s * cos((PI/8.0)*i*(j+0.5));
+  }
+}
+
+void fdct(block)
+short *block;
+{
+	register int i, j;
+	double s;
+	double tmp[64];
+
+	for(i = 0; i < 8; i++)
+    	for(j = 0; j < 8; j++)
+    	{
+    		s = 0.0;
+
+/*
+ *     		for(k = 0; k < 8; k++)
+ *         		s += c[j][k] * block[8 * i + k];
+ */
+        	s += c[j][0] * block[8 * i + 0];
+        	s += c[j][1] * block[8 * i + 1];
+        	s += c[j][2] * block[8 * i + 2];
+        	s += c[j][3] * block[8 * i + 3];
+        	s += c[j][4] * block[8 * i + 4];
+        	s += c[j][5] * block[8 * i + 5];
+        	s += c[j][6] * block[8 * i + 6];
+        	s += c[j][7] * block[8 * i + 7];
+
+    		tmp[8 * i + j] = s;
+    	}
+
+	for(j = 0; j < 8; j++)
+    	for(i = 0; i < 8; i++)
+    	{
+    		s = 0.0;
+
+/*
+ *     	  	for(k = 0; k < 8; k++)
+ *        	    s += c[i][k] * tmp[8 * k + j];
+ */
+        	s += c[i][0] * tmp[8 * 0 + j];
+        	s += c[i][1] * tmp[8 * 1 + j];
+        	s += c[i][2] * tmp[8 * 2 + j];
+        	s += c[i][3] * tmp[8 * 3 + j];
+        	s += c[i][4] * tmp[8 * 4 + j];
+        	s += c[i][5] * tmp[8 * 5 + j];
+        	s += c[i][6] * tmp[8 * 6 + j];
+        	s += c[i][7] * tmp[8 * 7 + j];
+
+    		block[8 * i + j] = (short)floor(s + 0.499999);
+/*
+ * reason for adding 0.499999 instead of 0.5:
+ * s is quite often x.5 (at least for i and/or j = 0 or 4)
+ * and setting the rounding threshold exactly to 0.5 leads to an
+ * extremely high arithmetic implementation dependency of the result;
+ * s being between x.5 and x.500001 (which is now incorrectly rounded
+ * downwards instead of upwards) is assumed to occur less often
+ * (if at all)
+ */
+      }
+}