lavfi/vf_colorchannelmixer: replace round by lrint

lrint is faster here on -ftree-vectorize with GCC. This is likely simply
an artifact of GCC's rather terrible auto-vectorizer, since as per the
instruction set manuals cvtsd2si and cvttsd2si (or their vector equivalents)
have identical cycle timings.

Anyway, regardless of above, lrint is superior to round accuracy wise.

Safety guaranteed as long int has at least 32 bits.

Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>

diff --git a/libavfilter/vf_colorchannelmixer.c b/libavfilter/vf_colorchannelmixer.c
index 0fffd341c5bb2dacb5490de12431270e1a5620b9..cda972dd002164626d840b250fb6e693578cb7c4 100644 (file)
--- a/libavfilter/vf_colorchannelmixer.c
+++ b/libavfilter/vf_colorchannelmixer.c
@@ -115,25 +115,25 @@ static int config_output(AVFilterLink *outlink)
             s->lut[i][j] = buffer;
 
     for (i = 0; i < size; i++) {
-        s->lut[R][R][i] = round(i * s->rr);
-        s->lut[R][G][i] = round(i * s->rg);
-        s->lut[R][B][i] = round(i * s->rb);
-        s->lut[R][A][i] = round(i * s->ra);
-
-        s->lut[G][R][i] = round(i * s->gr);
-        s->lut[G][G][i] = round(i * s->gg);
-        s->lut[G][B][i] = round(i * s->gb);
-        s->lut[G][A][i] = round(i * s->ga);
-
-        s->lut[B][R][i] = round(i * s->br);
-        s->lut[B][G][i] = round(i * s->bg);
-        s->lut[B][B][i] = round(i * s->bb);
-        s->lut[B][A][i] = round(i * s->ba);
-
-        s->lut[A][R][i] = round(i * s->ar);
-        s->lut[A][G][i] = round(i * s->ag);
-        s->lut[A][B][i] = round(i * s->ab);
-        s->lut[A][A][i] = round(i * s->aa);
+        s->lut[R][R][i] = lrint(i * s->rr);
+        s->lut[R][G][i] = lrint(i * s->rg);
+        s->lut[R][B][i] = lrint(i * s->rb);
+        s->lut[R][A][i] = lrint(i * s->ra);
+
+        s->lut[G][R][i] = lrint(i * s->gr);
+        s->lut[G][G][i] = lrint(i * s->gg);
+        s->lut[G][B][i] = lrint(i * s->gb);
+        s->lut[G][A][i] = lrint(i * s->ga);
+
+        s->lut[B][R][i] = lrint(i * s->br);
+        s->lut[B][G][i] = lrint(i * s->bg);
+        s->lut[B][B][i] = lrint(i * s->bb);
+        s->lut[B][A][i] = lrint(i * s->ba);
+
+        s->lut[A][R][i] = lrint(i * s->ar);
+        s->lut[A][G][i] = lrint(i * s->ag);
+        s->lut[A][B][i] = lrint(i * s->ab);
+        s->lut[A][A][i] = lrint(i * s->aa);
     }
 
     return 0;