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new a1050d48b0 avcodec/j2kenc: Compute division only once, preshift bit
a1050d48b0 is described below
commit a1050d48b0df3f7c3fa1c631ec8e82528b3f7c85
Author: Zsolt Vadasz <[email protected]>
AuthorDate: Fri Jul 3 19:07:04 2026 +0200
Commit: michaelni <[email protected]>
CommitDate: Tue Aug 25 16:10:16 2026 +0000
avcodec/j2kenc: Compute division only once, preshift bit
Pre-shift n to the highest bit in put_bits(), and compute a division
outside of a hot loop in encode_tile().
---
libavcodec/j2kenc.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/libavcodec/j2kenc.c b/libavcodec/j2kenc.c
index cba4d18adf..ac18c66b99 100644
--- a/libavcodec/j2kenc.c
+++ b/libavcodec/j2kenc.c
@@ -153,13 +153,14 @@ typedef struct {
/** put n times val bit */
static void put_bits(Jpeg2000EncoderContext *s, int val, int n) // TODO:
optimize
{
+ val <<= 7;
while (n-- > 0){
if (s->bit_index == 8)
{
s->bit_index = *s->buf == 0xff;
*(++s->buf) = 0;
}
- *s->buf |= val << (7 - s->bit_index++);
+ *s->buf |= val >> s->bit_index++;
}
}
@@ -1384,11 +1385,12 @@ static int encode_tile(Jpeg2000EncoderContext *s,
Jpeg2000Tile *tile, int tileno
}
}
} else{
+ int64_t multiplier = (int64_t)(16384 * 65536 /
band->i_stepsize);
for (y = yy0; y < yy1; y++){
int *ptr = t1.data + (y-yy0)*t1.stride;
for (x = xx0; x < xx1; x++){
*ptr = (comp->i_data[(comp->coord[0][1] -
comp->coord[0][0]) * y + x]);
- *ptr = (int64_t)*ptr * (int64_t)(16384 *
65536 / band->i_stepsize) >> 15 - NMSEDEC_FRACBITS;
+ *ptr = (int64_t)*ptr * multiplier >> 15 -
NMSEDEC_FRACBITS;
ptr++;
}
}
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