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minor optimizations / simplifications

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Originally committed as revision 367 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2002-03-29 01:53:59 +00:00
parent 60e575acc8
commit dbbe89994b
1 changed files with 14 additions and 23 deletions
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37
libavcodec/msmpeg4.c
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@ -226,18 +226,17 @@ void msmpeg4_encode_ext_header(MpegEncContext * s)
/* predict coded block */ /* predict coded block */
static inline int coded_block_pred(MpegEncContext * s, int n, UINT8 **coded_block_ptr) static inline int coded_block_pred(MpegEncContext * s, int n, UINT8 **coded_block_ptr)
{ {
int x, y, wrap, pred, a, b, c; int xy, wrap, pred, a, b, c;
x = 2 * s->mb_x + 1 + (n & 1); xy = s->block_index[n];
y = 2 * s->mb_y + 1 + ((n & 2) >> 1); wrap = s->block_wrap[0];
wrap = s->mb_width * 2 + 2;
/* B C /* B C
* A X * A X
*/ */
a = s->coded_block[(x - 1) + (y) * wrap]; a = s->coded_block[xy - 1 ];
b = s->coded_block[(x - 1) + (y - 1) * wrap]; b = s->coded_block[xy - 1 - wrap];
c = s->coded_block[(x) + (y - 1) * wrap]; c = s->coded_block[xy - wrap];
if (b == c) { if (b == c) {
pred = a; pred = a;
@ -246,7 +245,7 @@ static inline int coded_block_pred(MpegEncContext * s, int n, UINT8 **coded_bloc
} }
/* store value */ /* store value */
*coded_block_ptr = &s->coded_block[(x) + (y) * wrap]; *coded_block_ptr = &s->coded_block[xy];
return pred; return pred;
} }
@ -402,32 +401,24 @@ void msmpeg4_dc_scale(MpegEncContext * s)
static int msmpeg4_pred_dc(MpegEncContext * s, int n, static int msmpeg4_pred_dc(MpegEncContext * s, int n,
INT16 **dc_val_ptr, int *dir_ptr) INT16 **dc_val_ptr, int *dir_ptr)
{ {
int a, b, c, xy, wrap, pred, scale; int a, b, c, wrap, pred, scale;
INT16 *dc_val; INT16 *dc_val;
/* find prediction */ /* find prediction */
if (n < 4) { if (n < 4) {
wrap = s->mb_width * 2 + 2;
xy = 2 * s->mb_y + 1 + ((n & 2) >> 1);
xy *= wrap;
xy += 2 * s->mb_x + 1 + (n & 1);
dc_val = s->dc_val[0];
scale = s->y_dc_scale; scale = s->y_dc_scale;
} else { } else {
wrap = s->mb_width + 2;
xy = s->mb_y + 1;
xy *= wrap;
xy += s->mb_x + 1;
dc_val = s->dc_val[n - 4 + 1];
scale = s->c_dc_scale; scale = s->c_dc_scale;
} }
wrap = s->block_wrap[n];
dc_val= s->dc_val[0] + s->block_index[n];
/* B C /* B C
* A X * A X
*/ */
a = dc_val[xy - 1]; a = dc_val[ - 1];
b = dc_val[xy - 1 - wrap]; b = dc_val[ - 1 - wrap];
c = dc_val[xy - wrap]; c = dc_val[ - wrap];
/* XXX: the following solution consumes divisions, but it does not /* XXX: the following solution consumes divisions, but it does not
necessitate to modify mpegvideo.c. The problem comes from the necessitate to modify mpegvideo.c. The problem comes from the
@ -478,7 +469,7 @@ static int msmpeg4_pred_dc(MpegEncContext * s, int n,
} }
/* update predictor */ /* update predictor */
*dc_val_ptr = &dc_val[xy]; *dc_val_ptr = &dc_val[0];
return pred; return pred;
} }