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raise the fixed-point precision for the rescaler

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for super-large upscaling factor (32x and up), 20bits was not enough.

Change-Id: I7b0d1975d0609948d464cfc3aeff1a70df16dc57
This commit is contained in:
Pascal Massimino 2011-05-16 17:11:32 -07:00
parent aa87e4e063
commit 416b7a6b95
1 changed files with 3 additions and 3 deletions
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6
src/enc/picture.c
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@ -222,7 +222,7 @@ int WebPPictureCrop(WebPPicture* const pic,
//-----------------------------------------------------------------------------
// Simple picture rescaler
#define RFIX 20
#define RFIX 30
#define MULT(x,y) (((int64_t)(x) * (y) + (1 << (RFIX - 1))) >> RFIX)
static inline void ImportRow(const uint8_t* src, int src_width,
int32_t* frow, int32_t* irow, int dst_width) {
@ -264,7 +264,7 @@ static inline void ImportRow(const uint8_t* src, int src_width,
}
static void ExportRow(int32_t* frow, int32_t* irow, uint8_t* dst, int dst_width,
const int yscale, const int fxy_scale) {
const int yscale, const int64_t fxy_scale) {
int x_out;
for (x_out = 0; x_out < dst_width; ++x_out) {
const int frac = MULT(frow[x_out], yscale);
@ -281,7 +281,7 @@ static void RescalePlane(const uint8_t* src,
int32_t* const work) {
const int x_expand = (src_width < dst_width);
const int fy_scale = (1 << RFIX) / dst_height;
const int fxy_scale = x_expand ?
const int64_t fxy_scale = x_expand ?
((int64_t)dst_height << RFIX) / (dst_width * src_height) :
((int64_t)dst_height << RFIX) / (src_width * src_height);
int y_accum = src_height;