[Ffmpeg-cvslog] r6039 - trunk/libavcodec/mpegaudiodec.c
michael
subversion
Mon Aug 21 14:12:44 CEST 2006
Author: michael
Date: Mon Aug 21 14:12:43 2006
New Revision: 6039
Modified:
trunk/libavcodec/mpegaudiodec.c
Log:
replace a few MULL by MULH
Modified: trunk/libavcodec/mpegaudiodec.c
==============================================================================
--- trunk/libavcodec/mpegaudiodec.c (original)
+++ trunk/libavcodec/mpegaudiodec.c Mon Aug 21 14:12:43 2006
@@ -943,6 +943,19 @@
FIXR(5.73685662283492756461),
};
+/* 0.5 / cos(pi*(2*i+1)/36) */
+static const int icos36h[9] = {
+ FIXHR(0.50190991877167369479/2),
+ FIXHR(0.51763809020504152469/2), //0
+ FIXHR(0.55168895948124587824/2),
+ FIXHR(0.61038729438072803416/2),
+ FIXHR(0.70710678118654752439/2), //1
+ FIXHR(0.87172339781054900991/2),
+ FIXHR(1.18310079157624925896/4),
+ FIXHR(1.93185165257813657349/4), //2
+// FIXHR(5.73685662283492756461),
+};
+
/* 12 points IMDCT. We compute it "by hand" by factorizing obvious
cases. */
static void imdct12(int *out, int *in)
@@ -959,10 +972,10 @@
in3 += in1;
in2= MULH(2*in2, C3);
- in3= MULH(2*in3, C3);
+ in3= MULH(4*in3, C3);
t1 = in0 - in4;
- t2 = MULL(in1 - in5, icos36[4]);
+ t2 = MULH(2*(in1 - in5), icos36h[4]);
out[ 7]=
out[10]= t1 + t2;
@@ -971,19 +984,19 @@
in0 += in4>>1;
in4 = in0 + in2;
- in1 += in5>>1;
- in5 = MULL(in1 + in3, icos36[1]);
+ in5 += 2*in1;
+ in1 = MULH(in5 + in3, icos36h[1]);
out[ 8]=
- out[ 9]= in4 + in5;
+ out[ 9]= in4 + in1;
out[ 2]=
- out[ 3]= in4 - in5;
+ out[ 3]= in4 - in1;
in0 -= in2;
- in1 = MULL(in1 - in3, icos36[7]);
+ in5 = MULH(2*(in5 - in3), icos36h[7]);
out[ 0]=
- out[ 5]= in0 - in1;
+ out[ 5]= in0 - in5;
out[ 6]=
- out[11]= in0 + in1;
+ out[11]= in0 + in5;
}
/* cos(pi*i/18) */
@@ -1077,7 +1090,7 @@
t2 = tmp[i + 1];
t3 = tmp[i + 3];
- s1 = MULL(t3 + t2, icos36[j]);
+ s1 = MULH(2*(t3 + t2), icos36h[j]);
s3 = MULL(t3 - t2, icos36[8 - j]);
t0 = s0 + s1;
@@ -1097,7 +1110,7 @@
}
s0 = tmp[16];
- s1 = MULL(tmp[17], icos36[4]);
+ s1 = MULH(2*tmp[17], icos36h[4]);
t0 = s0 + s1;
t1 = s0 - s1;
out[(9 + 4)*SBLIMIT] = MULH(t1, win[9 + 4]) + buf[9 + 4];
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