[FFmpeg-devel] [PATCH] VP8: don't overread edges on fourtap MC.

[Ronald S. Bultje]

Fix C VP8 H+V MC functions which do two-dimensional 4/6-tap filters to
not overread beyond their edges if the second filter is 4-tap, since
the outer pixels aren't there anymore since
44002d8323023c35f51d523a7d305e45103ba7a1.
---
 libavcodec/vp8dsp.c |   34 +++++++++++++++++-----------------
 1 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/libavcodec/vp8dsp.c b/libavcodec/vp8dsp.c
index b8cf0b2..6b6a017 100644
--- a/libavcodec/vp8dsp.c
+++ b/libavcodec/vp8dsp.c
@@ -359,24 +359,24 @@ static void put_vp8_epel ## SIZE ## _ ## FILTERNAME ## _c(uint8_t *dst, int dsts
         src += srcstride; \
     } \
 }
-#define VP8_EPEL_HV(SIZE, FILTERX, FILTERY, FILTERNAME) \
+#define VP8_EPEL_HV(SIZE, FILTERX, ISFOURTAP, FILTERY, FILTERNAME) \
 static void put_vp8_epel ## SIZE ## _ ## FILTERNAME ## _c(uint8_t *dst, int dststride, uint8_t *src, int srcstride, int h, int mx, int my) \
 { \
     const uint8_t *filter = subpel_filters[mx-1]; \
     uint8_t *cm = ff_cropTbl + MAX_NEG_CROP; \
     int x, y; \
-    uint8_t tmp_array[(2*SIZE+5)*SIZE]; \
+    uint8_t tmp_array[(2*SIZE+(5-2*ISFOURTAP))*SIZE]; \
     uint8_t *tmp = tmp_array; \
-    src -= 2*srcstride; \
+    src -= (2-ISFOURTAP)*srcstride; \
 \
-    for (y = 0; y < h+5; y++) { \
+    for (y = 0; y < h+5-(2*ISFOURTAP); y++) { \
         for (x = 0; x < SIZE; x++) \
             tmp[x] = FILTERX(src, filter, 1); \
         tmp += SIZE; \
         src += srcstride; \
     } \
 \
-    tmp = tmp_array + 2*SIZE; \
+    tmp = tmp_array + (2-ISFOURTAP)*SIZE; \
     filter = subpel_filters[my-1]; \
 \
     for (y = 0; y < h; y++) { \
@@ -399,18 +399,18 @@ VP8_EPEL_V(4,  FILTER_4TAP, v4)
 VP8_EPEL_V(16, FILTER_6TAP, v6)
 VP8_EPEL_V(8,  FILTER_6TAP, v6)
 VP8_EPEL_V(4,  FILTER_6TAP, v6)
-VP8_EPEL_HV(16, FILTER_4TAP, FILTER_4TAP, h4v4)
-VP8_EPEL_HV(8,  FILTER_4TAP, FILTER_4TAP, h4v4)
-VP8_EPEL_HV(4,  FILTER_4TAP, FILTER_4TAP, h4v4)
-VP8_EPEL_HV(16, FILTER_4TAP, FILTER_6TAP, h4v6)
-VP8_EPEL_HV(8,  FILTER_4TAP, FILTER_6TAP, h4v6)
-VP8_EPEL_HV(4,  FILTER_4TAP, FILTER_6TAP, h4v6)
-VP8_EPEL_HV(16, FILTER_6TAP, FILTER_4TAP, h6v4)
-VP8_EPEL_HV(8,  FILTER_6TAP, FILTER_4TAP, h6v4)
-VP8_EPEL_HV(4,  FILTER_6TAP, FILTER_4TAP, h6v4)
-VP8_EPEL_HV(16, FILTER_6TAP, FILTER_6TAP, h6v6)
-VP8_EPEL_HV(8,  FILTER_6TAP, FILTER_6TAP, h6v6)
-VP8_EPEL_HV(4,  FILTER_6TAP, FILTER_6TAP, h6v6)
+VP8_EPEL_HV(16, FILTER_4TAP, 1, FILTER_4TAP, h4v4)
+VP8_EPEL_HV(8,  FILTER_4TAP, 1, FILTER_4TAP, h4v4)
+VP8_EPEL_HV(4,  FILTER_4TAP, 1, FILTER_4TAP, h4v4)
+VP8_EPEL_HV(16, FILTER_4TAP, 0, FILTER_6TAP, h4v6)
+VP8_EPEL_HV(8,  FILTER_4TAP, 0, FILTER_6TAP, h4v6)
+VP8_EPEL_HV(4,  FILTER_4TAP, 0, FILTER_6TAP, h4v6)
+VP8_EPEL_HV(16, FILTER_6TAP, 1, FILTER_4TAP, h6v4)
+VP8_EPEL_HV(8,  FILTER_6TAP, 1, FILTER_4TAP, h6v4)
+VP8_EPEL_HV(4,  FILTER_6TAP, 1, FILTER_4TAP, h6v4)
+VP8_EPEL_HV(16, FILTER_6TAP, 0, FILTER_6TAP, h6v6)
+VP8_EPEL_HV(8,  FILTER_6TAP, 0, FILTER_6TAP, h6v6)
+VP8_EPEL_HV(4,  FILTER_6TAP, 0, FILTER_6TAP, h6v6)
 
 #define VP8_BILINEAR(SIZE) \
 static void put_vp8_bilinear ## SIZE ## _h_c(uint8_t *dst, int stride, uint8_t *src, int s2, int h, int mx, int my) \
-- 
1.7.2.1