From: Matthew Fearnley <matthew.w.fearn...@gmail.com>
Store the value of *xored computed within block_cmp() in a local variable,
and only update the *xored parameter at the same time as *mx,*my are set.
This ensures that the value of *xored is accurate for the value of *mx,*my
whenever the function ends.
Note that the local variable is not needed in the intial block_cmp for (0,0)
because *mx,*my and *xored are all set there.
The previous logic worked by exiting early if ever !*xored, but put implicit
requirements on block_cmp() to:
- always return 0 if !xored
- never return a negative value
---
libavcodec/zmbvenc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/libavcodec/zmbvenc.c b/libavcodec/zmbvenc.c
index 2f041dae32..0e8ee5ce31 100644
--- a/libavcodec/zmbvenc.c
+++ b/libavcodec/zmbvenc.c
@@ -100,6 +100,7 @@ static int zmbv_me(ZmbvEncContext *c, uint8_t *src, int
sstride, uint8_t *prev,
int pstride, int x, int y, int *mx, int *my, int *xored)
{
int dx, dy, tx, ty, tv, bv, bw, bh;
+ int txored;
*mx = *my = 0;
bw = FFMIN(ZMBV_BLOCK, c->avctx->width - x);
@@ -111,11 +112,12 @@ static int zmbv_me(ZmbvEncContext *c, uint8_t *src, int
sstride, uint8_t *prev,
if(tx == x && ty == y) continue; // we already tested this block
dx = tx - x;
dy = ty - y;
- tv = block_cmp(c, src, sstride, prev + dx + dy * pstride, pstride,
bw, bh, xored);
+ tv = block_cmp(c, src, sstride, prev + dx + dy * pstride, pstride,
bw, bh, &txored);
if(tv < bv){
bv = tv;
*mx = dx;
*my = dy;
+ *xored = txored;
if(!bv) return 0;
}
}
--
2.17.1
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