shithub: libvpx

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Shortcut 8x8/16x16 inverse 2D-DCT

This commit brought back the shortcut implementation of 8x8/16x16
inverse 2D-DCT. When the eob <= 10, it skips the inverse transform
operations on row 4:7/4:15 in the first round. For bus_cif at 1000
kbps, this provides about 2% speed-up at speed 0.

Change-Id: I453e2d72956467d75be4ad8c04b4482ab889d572

--- a/vp9/decoder/vp9_idct_blk.c

+++ b/vp9/decoder/vp9_idct_blk.c

@@ -95,6 +95,9 @@

       // DC only DCT coefficient

       vp9_short_idct8x8_1_add(input, dest, stride);

       input[0] = 0;

+    } else if (eob <= 10) {

+      vp9_short_idct10_8x8_add(input, dest, stride);

+      vpx_memset(input, 0, 128);

     } else {

       vp9_short_idct8x8_add(input, dest, stride);

       vpx_memset(input, 0, 128);

@@ -128,6 +131,9 @@

       input[0] = 0;

       vp9_add_constant_residual_16x16(out, dest, stride);

+    } else if (eob <= 10) {

+      vp9_short_idct10_16x16_add(input, dest, stride);

+      vpx_memset(input, 0, 512);

     } else {

       vp9_short_idct16x16_add(input, dest, stride);

       vpx_memset(input, 0, 512);

--- a/vp9/encoder/vp9_encodemb.c

+++ b/vp9/encoder/vp9_encodemb.c

@@ -52,10 +52,21 @@

                                         int stride) {

   if (eob <= 1)

     vp9_short_idct8x8_1_add(dqcoeff, dest, stride);

+  else if (eob <= 10)

+    vp9_short_idct10_8x8_add(dqcoeff, dest, stride);

   else

     vp9_short_idct8x8_add(dqcoeff, dest, stride);

 }

+static void inverse_transform_b_16x16_add(MACROBLOCKD *xd, int eob,

+                                          int16_t *dqcoeff, uint8_t *dest,

+                                          int stride) {

+  if (eob <= 10)

+    vp9_short_idct10_16x16_add(dqcoeff, dest, stride);

+  else

+    vp9_short_idct16x16_add(dqcoeff, dest, stride);

+}

+

 static void subtract_plane(MACROBLOCK *x, BLOCK_SIZE_TYPE bsize, int plane) {

   struct macroblock_plane *const p = &x->plane[plane];

   const MACROBLOCKD *const xd = &x->e_mbd;

@@ -538,7 +549,8 @@

       vp9_short_idct32x32_add(dqcoeff, dst, pd->dst.stride);

       break;

     case TX_16X16:

-      vp9_short_idct16x16_add(dqcoeff, dst, pd->dst.stride);

+      inverse_transform_b_16x16_add(xd, pd->eobs[block], dqcoeff,

+                                    dst, pd->dst.stride);

       break;

     case TX_8X8:

       inverse_transform_b_8x8_add(xd, pd->eobs[block], dqcoeff,

@@ -691,7 +703,7 @@

                      pd->dequant, p->zbin_extra, eob, scan, iscan);

       if (!x->skip_encode && *eob) {

         if (tx_type == DCT_DCT)

-          vp9_short_idct16x16_add(dqcoeff, dst, pd->dst.stride);

+          inverse_transform_b_16x16_add(xd, *eob, dqcoeff, dst, pd->dst.stride);

         else

           vp9_short_iht16x16_add(dqcoeff, dst, pd->dst.stride, tx_type);

       }