shithub: dav1d

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Don't backup pixel if next block not "CDEFed"

--- a/src/cdef_apply_tmpl.c

+++ b/src/cdef_apply_tmpl.c

@@ -33,6 +33,12 @@

 #include "src/cdef_apply.h"

+

+enum Backup2x8Flags {

+    BACKUP_2X8_Y = 1 << 0,

+    BACKUP_2X8_UV = 1 << 1,

+};

+

 static void backup2lines(pixel *const dst[3][2],

                          /*const*/ pixel *const src[3],

                          const ptrdiff_t src_stride[2], int y_off, int w,

@@ -56,13 +62,18 @@

 static void backup2x8(pixel dst[3][8][2],

                       /*const*/ pixel *const src[3],

                       const ptrdiff_t src_stride[2], int x_off,

-                      const enum Dav1dPixelLayout layout)

+                      const enum Dav1dPixelLayout layout,

+                      const enum Backup2x8Flags flag)

 {

     ptrdiff_t y_off = 0;

-    for (int y = 0; y < 8; y++, y_off += PXSTRIDE(src_stride[0]))

-        pixel_copy(dst[0][y], &src[0][y_off + x_off - 2], 2);

+    if (flag & BACKUP_2X8_Y) {

+        for (int y = 0; y < 8; y++, y_off += PXSTRIDE(src_stride[0]))

+            pixel_copy(dst[0][y], &src[0][y_off + x_off - 2], 2);

+    }

-    if (layout == DAV1D_PIXEL_LAYOUT_I400) return;

+    if (layout == DAV1D_PIXEL_LAYOUT_I400 || !(flag & BACKUP_2X8_UV))

+        return;

+

     const int ss_ver = layout == DAV1D_PIXEL_LAYOUT_I420;

     const int ss_hor = layout != DAV1D_PIXEL_LAYOUT_I444;

@@ -98,13 +109,9 @@

     const int ss_ver = layout == DAV1D_PIXEL_LAYOUT_I420;

     const int ss_hor = layout != DAV1D_PIXEL_LAYOUT_I444;

-    // FIXME a design improvement that could be made here is to keep a set of

-    // flags for each block position on whether the block was filtered; if not,

-    // the backup of pre-filter data is empty, and the restore is therefore

-    // unnecessary as well.

-

     for (int bit = 0, by = by_start; by < by_end; by += 2, edges |= CDEF_HAVE_TOP) {

         const int tf = f->lf.top_pre_cdef_toggle;

+        const int by_idx = by & 30;

         if (by + 2 >= f->bh) edges &= ~CDEF_HAVE_BOTTOM;

         if (edges & CDEF_HAVE_BOTTOM) {

@@ -117,6 +124,7 @@

         pixel *iptrs[3] = { ptrs[0], ptrs[1], ptrs[2] };

         edges &= ~CDEF_HAVE_LEFT;

         edges |= CDEF_HAVE_RIGHT;

+        enum Backup2x8Flags prev_flag = 0;

         for (int sbx = 0, last_skip = 1; sbx < sb64w; sbx++, edges |= CDEF_HAVE_LEFT) {

             const int sb128x = sbx >>1;

             const int sb64_idx = ((by & sbsz) >> 3) + (sbx & 1);

@@ -131,6 +139,8 @@

             const int y_lvl = f->frame_hdr->cdef.y_strength[cdef_idx];

             const int uv_lvl = f->frame_hdr->cdef.uv_strength[cdef_idx];

+            const enum Backup2x8Flags flag = !!y_lvl + (!!uv_lvl << 1);

+

             pixel *bptrs[3] = { iptrs[0], iptrs[1], iptrs[2] };

             for (int bx = sbx * sbsz; bx < imin((sbx + 1) * sbsz, f->bw);

                  bx += 2, edges |= CDEF_HAVE_LEFT)

@@ -140,7 +150,7 @@

                 // check if this 8x8 block had any coded coefficients; if not,

                 // go to the next block

                 const unsigned bx_mask = 3U << (bx & 14);

-                const int by_idx = by & 30, bx_idx = (bx & 16) >> 4;

+                const int bx_idx = (bx & 16) >> 4;

                 if (!((lflvl[sb128x].noskip_mask[by_idx + 0][bx_idx] |

                        lflvl[sb128x].noskip_mask[by_idx + 1][bx_idx]) & bx_mask))

                 {

@@ -147,15 +157,16 @@

                     last_skip = 1;

                     goto next_b;

                 }

-

-                if (last_skip && edges & CDEF_HAVE_LEFT) {

+                const int do_left = last_skip ? flag : (prev_flag ^ flag) & flag;

+                prev_flag = flag;

+                if (do_left && edges & CDEF_HAVE_LEFT) {

                     // we didn't backup the prefilter data because it wasn't

                     // there, so do it here instead

-                    backup2x8(lr_bak[bit], bptrs, f->cur.stride, 0, layout);

+                    backup2x8(lr_bak[bit], bptrs, f->cur.stride, 0, layout, do_left);

                 }

                 if (edges & CDEF_HAVE_RIGHT) {

                     // backup pre-filter data for next iteration

-                    backup2x8(lr_bak[!bit], bptrs, f->cur.stride, 8, layout);

+                    backup2x8(lr_bak[!bit], bptrs, f->cur.stride, 8, layout, flag);

                 }

                 // the actual filter