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higher accuracy

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Originally committed as revision 897 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2002-09-01 20:54:38 +00:00
parent 81e0d0b412
commit 004c18ee9c
1 changed files with 4 additions and 2 deletions
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6
libavcodec/jfdctint.c
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@ -30,8 +30,10 @@
#define SHIFT_TEMPS #define SHIFT_TEMPS
#define DCTSIZE 8 #define DCTSIZE 8
#define BITS_IN_JSAMPLE 8
#define GLOBAL(x) x #define GLOBAL(x) x
#define RIGHT_SHIFT(x, n) ((x) >> (n)) #define RIGHT_SHIFT(x, n) ((x) >> (n))
#define MULTIPLY16C16(var,const) ((var)*(const))
#if 1 //def USE_ACCURATE_ROUNDING #if 1 //def USE_ACCURATE_ROUNDING
#define DESCALE(x,n) RIGHT_SHIFT((x) + (1 << ((n) - 1)), n) #define DESCALE(x,n) RIGHT_SHIFT((x) + (1 << ((n) - 1)), n)
@ -85,7 +87,7 @@
#if BITS_IN_JSAMPLE == 8 #if BITS_IN_JSAMPLE == 8
#define CONST_BITS 13 #define CONST_BITS 13
#define PASS1_BITS 2 #define PASS1_BITS 4 /* set this to 2 if 16x16 multiplies are faster */
#else #else
#define CONST_BITS 13 #define CONST_BITS 13
#define PASS1_BITS 1 /* lose a little precision to avoid overflow */ #define PASS1_BITS 1 /* lose a little precision to avoid overflow */
@ -134,7 +136,7 @@
* For 12-bit samples, a full 32-bit multiplication will be needed. * For 12-bit samples, a full 32-bit multiplication will be needed.
*/ */
#if BITS_IN_JSAMPLE == 8 #if BITS_IN_JSAMPLE == 8 && CONST_BITS<=13 && PASS1_BITS<=2
#define MULTIPLY(var,const) MULTIPLY16C16(var,const) #define MULTIPLY(var,const) MULTIPLY16C16(var,const)
#else #else
#define MULTIPLY(var,const) ((var) * (const)) #define MULTIPLY(var,const) ((var) * (const))