shithub: dav1d

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Fix 64 pixel super block row loop restoration

Fix for issue #20

--- a/src/lr_apply.c

+++ b/src/lr_apply.c

@@ -40,25 +40,34 @@

     LR_RESTORE_V = 1 << 2,

 };

+// The loop filter buffer stores 12 rows of pixels. A superblock block will

+// contain at most 2 stripes. Each stripe requires 4 rows pixels (2 above

+// and 2 below) the final 4 rows are used to swap the bottom of the last

+// stripe with the top of the next super block row.

 static void backup_lpf(pixel *dst, ptrdiff_t dst_stride,

                        const pixel *src, ptrdiff_t src_stride,

-                       const int first_stripe_h, const int next_stripe_h,

-                       int row, const int row_h, const int w, const int h)

+                       const int ss_ver, const int sb128,

+                       int row, const int row_h, const int w)

 {

     src_stride = PXSTRIDE(src_stride);

     dst_stride = PXSTRIDE(dst_stride);

+

+    // The first stripe of the frame is shorter by 8 luma pixel rows.

+    int stripe_h = (64 - 8 * !row) >> ss_ver;

+

     if (row) {

+        const int top = 4 << sb128;

         // Copy the top part of the stored loop filtered pixels from the

         // previous sb row needed above the first stripe of this sb row.

-        pixel_copy(&dst[dst_stride *  0], &dst[dst_stride *  8], w);

-        pixel_copy(&dst[dst_stride *  1], &dst[dst_stride *  9], w);

-        pixel_copy(&dst[dst_stride *  2], &dst[dst_stride * 10], w);

-        pixel_copy(&dst[dst_stride *  3], &dst[dst_stride * 11], w);

+        pixel_copy(&dst[dst_stride *  0], &dst[dst_stride *  top], w);

+        pixel_copy(&dst[dst_stride *  1], &dst[dst_stride * (top + 1)], w);

+        pixel_copy(&dst[dst_stride *  2], &dst[dst_stride * (top + 2)], w);

+        pixel_copy(&dst[dst_stride *  3], &dst[dst_stride * (top + 3)], w);

     }

-    int stripe_h = first_stripe_h;

     dst += 4 * dst_stride;

     src += (stripe_h - 2) * src_stride;

+

     for (; row + stripe_h <= row_h; row += stripe_h) {

         for (int i = 0; i < 4; i++) {

             pixel_copy(dst, src, w);

@@ -65,7 +74,7 @@

             dst += dst_stride;

             src += src_stride;

         }

-        stripe_h = next_stripe_h;

+        stripe_h = 64 >> ss_ver;

         src += (stripe_h - 4) * src_stride;

     }

 }

@@ -73,7 +82,6 @@

 void bytefn(dav1d_lr_copy_lpf)(Dav1dFrameContext *const f,

                                /*const*/ pixel *const src[3], const int sby)

 {

-    const int stripe_h = 64 - (8 * !sby);

     const ptrdiff_t offset = 8 * !!sby;

     const ptrdiff_t *const src_stride = f->cur.p.stride;

@@ -89,8 +97,8 @@

         const int row_h = imin((sby + 1) << (6 + f->seq_hdr.sb128), h);

         const int y_stripe = (sby << (6 + f->seq_hdr.sb128)) - offset;

         backup_lpf(f->lf.lr_lpf_line_ptr[0], sizeof(pixel) * f->b4_stride * 4,

-                   src[0] - offset * PXSTRIDE(src_stride[0]),

-                   src_stride[0], stripe_h, 64, y_stripe, row_h, w, h);

+                   src[0] - offset * PXSTRIDE(src_stride[0]), src_stride[0],

+                   0, f->seq_hdr.sb128, y_stripe, row_h, w);

     }

     if (restore_planes & (LR_RESTORE_U | LR_RESTORE_V)) {

         const int ss_ver = f->cur.p.p.layout == DAV1D_PIXEL_LAYOUT_I420;

@@ -98,7 +106,6 @@

         const int h = f->bh << (2 - ss_ver);

         const int w = f->bw << (2 - ss_hor);

         const int row_h = imin((sby + 1) << ((6 - ss_ver) + f->seq_hdr.sb128), h);

-        const int stripe_h_uv = stripe_h >> ss_ver;

         const ptrdiff_t offset_uv = offset >> ss_ver;

         const int y_stripe =

             (sby << ((6 - ss_ver) + f->seq_hdr.sb128)) - offset_uv;

@@ -105,15 +112,13 @@

         if (restore_planes & LR_RESTORE_U) {

             backup_lpf(f->lf.lr_lpf_line_ptr[1], sizeof(pixel) * f->b4_stride * 4,

-                       src[1] - offset_uv * PXSTRIDE(src_stride[1]),

-                       src_stride[1], stripe_h_uv, 32, y_stripe,

-                       row_h, w, h);

+                       src[1] - offset_uv * PXSTRIDE(src_stride[1]), src_stride[1],

+                       ss_ver, f->seq_hdr.sb128, y_stripe, row_h, w);

         }

         if (restore_planes & LR_RESTORE_V) {

             backup_lpf(f->lf.lr_lpf_line_ptr[2], sizeof(pixel) * f->b4_stride * 4,

-                       src[2] - offset_uv * PXSTRIDE(src_stride[1]),

-                       src_stride[1], stripe_h_uv, 32, y_stripe,

-                       row_h, w, h);

+                       src[2] - offset_uv * PXSTRIDE(src_stride[1]), src_stride[1],

+                       ss_ver, f->seq_hdr.sb128, y_stripe, row_h, w);

         }

     }

 }