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avcodec/jpeg2000dec: Add 5/3 de-quantization special case for the lossless case 

This avoids a multiplication and 64bits

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2015-06-24 17:05:42 +02:00
parent 8ff09e9098
commit 05ef6324d1
1 changed files with 8 additions and 2 deletions
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10
libavcodec/jpeg2000dec.c
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@ -1436,8 +1436,14 @@ static void dequantization_int(int x, int y, Jpeg2000Cblk *cblk,
for (j = 0; j < (cblk->coord[1][1] - cblk->coord[1][0]); ++j) {
int32_t *datap = &comp->i_data[(comp->coord[0][1] - comp->coord[0][0]) * (y + j) + x];
int *src = t1->data[j];
for (i = 0; i < w; ++i)
datap[i] = (src[i] * (int64_t)band->i_stepsize) / 32768;
if (band->i_stepsize == 16384) {
for (i = 0; i < w; ++i)
datap[i] = src[i] / 2;
} else {
// This should be VERY uncommon
for (i = 0; i < w; ++i)
datap[i] = (src[i] * (int64_t)band->i_stepsize) / 32768;
}
}
}