From 05ef6324d11017420a087150f2addbb18cdb9ad3 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Wed, 24 Jun 2015 17:05:42 +0200
Subject: [PATCH] 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>
---
libavcodec/jpeg2000dec.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index be78660911f..11f4cd6ff6c 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -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;
+ }
}
}
--
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