[FFmpeg-devel,6/9] avcodec/gdv: Eliminate 50% of the reads in the first inner loop in rescale()

Submitted by Michael Niedermayer on Aug. 5, 2018, 8:29 p.m.

Details

Message ID 20180805202937.7563-6-michael@niedermayer.cc
State Accepted
Commit 5f84fbce08769fb21d8459b81e9aad53635008b7
Headers show

Commit Message

Michael Niedermayer Aug. 5, 2018, 8:29 p.m.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/gdv.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

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diff --git a/libavcodec/gdv.c b/libavcodec/gdv.c
index 595d8ff4e4..aea15a88ef 100644
--- a/libavcodec/gdv.c
+++ b/libavcodec/gdv.c
@@ -85,9 +85,15 @@  static void rescale(GDVContext *gdv, uint8_t *dst, int w, int h, int scale_v, in
             int y = h - j - 1;
             uint8_t *dst1 = dst + PREAMBLE_SIZE + y * w;
             uint8_t *src1 = dst + PREAMBLE_SIZE + (y>>!!gdv->scale_h) * (w>>1);
-            for (x = w - 1; x >= 0; x--) {
+
+            for (x = w - 1; x >= 0 && !(x&1); x--) {
                 dst1[x] = src1[(x>>1)];
             }
+
+            for (x--; x >= 0; x-=2) {
+                dst1[x  ] =
+                dst1[x+1] = src1[(x>>1)];
+            }
         }
     } else if (gdv->scale_h) {
         for (j = 0; j < h; j++) {