[SCM] libav/experimental: Don't do edge emulation unless the edge pixels will be used in MC.

[siretart at users.alioth.debian.org]

The following commit has been merged in the experimental branch:
commit 44002d8323023c35f51d523a7d305e45103ba7a1
Author: Ronald S. Bultje <rsbultje at gmail.com>
Date:   Tue Jan 25 12:25:07 2011 -0500

    Don't do edge emulation unless the edge pixels will be used in MC.
    
    Do not emulate larger edges than we will actually use for this round of
    MC. Decoding goes from avg+SE 29.972+/-0.023sec to 29.856+/-0.023, i.e.
    0.12sec or ~0.4% faster.

diff --git a/libavcodec/vp8.c b/libavcodec/vp8.c
index 80d30e8..52a3f90 100644
--- a/libavcodec/vp8.c
+++ b/libavcodec/vp8.c
@@ -1218,21 +1218,26 @@ void vp8_mc(VP8Context *s, int luma,
             vp8_mc_func mc_func[3][3])
 {
     if (AV_RN32A(mv)) {
-        static const uint8_t idx[8] = { 0, 1, 2, 1, 2, 1, 2, 1 };
-        int mx = (mv->x << luma)&7, mx_idx = idx[mx];
-        int my = (mv->y << luma)&7, my_idx = idx[my];
+        static const uint8_t idx[3][8] = {
+            { 0, 1, 2, 1, 2, 1, 2, 1 }, // nr. of left extra pixels,
+                                        // also function pointer index
+            { 0, 3, 5, 3, 5, 3, 5, 3 }, // nr. of extra pixels required
+            { 0, 2, 3, 2, 3, 2, 3, 2 }, // nr. of right extra pixels
+        };
+        int mx = (mv->x << luma)&7, mx_idx = idx[0][mx];
+        int my = (mv->y << luma)&7, my_idx = idx[0][my];
 
         x_off += mv->x >> (3 - luma);
         y_off += mv->y >> (3 - luma);
 
         // edge emulation
         src += y_off * linesize + x_off;
-        if (x_off < 2 || x_off >= width  - block_w - 3 ||
-            y_off < 2 || y_off >= height - block_h - 3) {
-            ff_emulated_edge_mc(s->edge_emu_buffer, src - 2 * linesize - 2, linesize,
-                                block_w + 5, block_h + 5,
-                                x_off - 2, y_off - 2, width, height);
-            src = s->edge_emu_buffer + 2 + linesize * 2;
+        if (x_off < mx_idx || x_off >= width  - block_w - idx[2][mx] ||
+            y_off < my_idx || y_off >= height - block_h - idx[2][my]) {
+            ff_emulated_edge_mc(s->edge_emu_buffer, src - my_idx * linesize - mx_idx, linesize,
+                                block_w + idx[1][mx], block_h + idx[1][my],
+                                x_off - mx_idx, y_off - my_idx, width, height);
+            src = s->edge_emu_buffer + mx_idx + linesize * my_idx;
         }
         mc_func[my_idx][mx_idx](dst, linesize, src, linesize, block_h, mx, my);
     } else

-- 
Libav/FFmpeg packaging