Replace MPEG group reference DCT implementation by newly rewritten version.

patch by Dylan Yudaken, dyudaken gmail com

Originally committed as revision 18274 to svn://svn.ffmpeg.org/ffmpeg/trunk

LICENSE

@@ -31,7 +31,3 @@ There are a handful of files under other licensing terms, namely:
 
 * The files libavcodec/jfdctfst.c, libavcodec/jfdctint.c, libavcodec/jrevdct.c
   are taken from libjpeg, see the top of the files for licensing details.
-
-* The file libavcodec/fdctref.c is copyrighted by the MPEG Software Simulation
-  Group with all rights reserved. It is only used to create a DCT test program
-  and not compiled into libavcodec.

doc/TODO

@@ -81,7 +81,6 @@ unassigned TODO: (unordered)
 - add support for using mplayers video filters to ffmpeg
 - H264 encoder
 - per MB ratecontrol (so VCD and such do work better)
-- replace/rewrite libavcodec/fdctref.c
 - write a script which iteratively changes all functions between always_inline and noinline and benchmarks the result to find the best set of inlined functions
 - convert all the non SIMD asm into small asm vs. C testcases and submit them to the gcc devels so they can improve gcc
 - generic audio mixing API

libavcodec/Makefile

@@ -541,4 +541,4 @@ DIRS = alpha arm bfin mlib ppc ps2 sh4 sparc x86
 
 include $(SUBDIR)../subdir.mak
 
-$(SUBDIR)dct-test$(EXESUF): $(SUBDIR)fdctref.o $(SUBDIR)aandcttab.o
+$(SUBDIR)dct-test$(EXESUF): $(SUBDIR)dctref.o $(SUBDIR)aandcttab.o

libavcodec/fdctref.c

-/**
- * @file libavcodec/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>
-
-#ifndef PI
-# ifdef M_PI
-#  define PI M_PI
-# else
-#  define PI 3.14159265358979323846
-# endif
-#endif
-
-/* global declarations */
-void ff_ref_dct_init (void);
-void ff_ref_fdct (short *block);
-
-/* private data */
-static double c[8][8]; /* transform coefficients */
-
-void ff_ref_dct_init(void)
-{
-  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 ff_ref_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];
-                s*=8.0;
-
-                    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)
- */
-      }
-}
-
-/* perform IDCT matrix multiply for 8x8 coefficient block */
-
-void ff_ref_idct(block)
-short *block;
-{
-  int i, j, k, v;
-  double partial_product;
-  double tmp[64];
-
-  for (i=0; i<8; i++)
-    for (j=0; j<8; j++)
-    {
-      partial_product = 0.0;
-
-      for (k=0; k<8; k++)
-        partial_product+= c[k][j]*block[8*i+k];
-
-      tmp[8*i+j] = partial_product;
-    }
-
-  /* Transpose operation is integrated into address mapping by switching
-     loop order of i and j */
-
-  for (j=0; j<8; j++)
-    for (i=0; i<8; i++)
-    {
-      partial_product = 0.0;
-
-      for (k=0; k<8; k++)
-        partial_product+= c[k][i]*tmp[8*k+j];
-
-      v = (int) floor(partial_product+0.5);
-      block[8*i+j] = v;
-    }
-}