shithub: libvpx

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Simplify rdmult computation

Recognizing that max dc_quant used in rdmult computation is 21387 and
21387 * 21387 * 88 / 24 is still within the range of int32_t, this
commit simplifies the computation with minor cleanups.

Change-Id: I2ac7e8315d103c0bb39b70c312c87c0fda47b4f9

--- a/vp9/encoder/vp9_encoder.c

+++ b/vp9/encoder/vp9_encoder.c

@@ -6241,9 +6241,7 @@

   xd->cur_buf = this_frame;

   // Get rd multiplier set up.

-  rdmult =

-      (int)vp9_compute_rd_mult_based_on_qindex(cpi, tpl_frame->base_qindex);

-  if (rdmult < 1) rdmult = 1;

+  rdmult = vp9_compute_rd_mult_based_on_qindex(cpi, tpl_frame->base_qindex);

   set_error_per_bit(&cpi->td.mb, rdmult);

   vp9_initialize_me_consts(cpi, &cpi->td.mb, tpl_frame->base_qindex);

--- a/vp9/encoder/vp9_rd.c

+++ b/vp9/encoder/vp9_rd.c

@@ -173,27 +173,23 @@

 static const int rd_frame_type_factor[FRAME_UPDATE_TYPES] = { 128, 144, 128,

                                                               128, 144, 144 };

-int64_t vp9_compute_rd_mult_based_on_qindex(const VP9_COMP *cpi, int qindex) {

-  const int64_t q = vp9_dc_quant(qindex, 0, cpi->common.bit_depth);

+int vp9_compute_rd_mult_based_on_qindex(const VP9_COMP *cpi, int qindex) {

+  // largest dc_quant is 21387, therefore rdmult should always fit in int32_t

+  const int q = vp9_dc_quant(qindex, 0, cpi->common.bit_depth);

+  int rdmult = q * q;

+  rdmult = rdmult * 3 + (rdmult * 2 / 3);

 #if CONFIG_VP9_HIGHBITDEPTH

-  int64_t rdmult = 0;

   switch (cpi->common.bit_depth) {

-    case VPX_BITS_8: rdmult = 88 * q * q / 24; break;

-    case VPX_BITS_10: rdmult = ROUND_POWER_OF_TWO(88 * q * q / 24, 4); break;

-    default:

-      assert(cpi->common.bit_depth == VPX_BITS_12);

-      rdmult = ROUND_POWER_OF_TWO(88 * q * q / 24, 8);

-      break;

+    case VPX_BITS_10: rdmult = ROUND_POWER_OF_TWO(rdmult, 4); break;

+    case VPX_BITS_12: rdmult = ROUND_POWER_OF_TWO(rdmult, 8); break;

+    default: break;

   }

-#else

-  int64_t rdmult = 88 * q * q / 24;

 #endif  // CONFIG_VP9_HIGHBITDEPTH

-  return rdmult;

+  return rdmult > 0 ? rdmult : 1;

 }

 int vp9_compute_rd_mult(const VP9_COMP *cpi, int qindex) {

   int64_t rdmult = vp9_compute_rd_mult_based_on_qindex(cpi, qindex);

-

   if (cpi->oxcf.pass == 2 && (cpi->common.frame_type != KEY_FRAME)) {

     const GF_GROUP *const gf_group = &cpi->twopass.gf_group;

     const FRAME_UPDATE_TYPE frame_type = gf_group->update_type[gf_group->index];

@@ -205,7 +201,6 @@

     rdmult = (rdmult * rd_frame_type_factor[frame_type]) >> 7;

     rdmult += ((rdmult * rd_boost_factor[boost_index]) >> 7);

   }

-  if (rdmult < 1) rdmult = 1;

   return (int)rdmult;

 }

--- a/vp9/encoder/vp9_rd.h

+++ b/vp9/encoder/vp9_rd.h

@@ -134,8 +134,7 @@

 struct VP9_COMP;

 struct macroblock;

-int64_t vp9_compute_rd_mult_based_on_qindex(const struct VP9_COMP *cpi,

-                                            int qindex);

+int vp9_compute_rd_mult_based_on_qindex(const struct VP9_COMP *cpi, int qindex);

 int vp9_compute_rd_mult(const struct VP9_COMP *cpi, int qindex);

--- a/vp9/encoder/vp9_temporal_filter.c

+++ b/vp9/encoder/vp9_temporal_filter.c

@@ -952,8 +952,7 @@

   }

   // Initialize errorperbit and sabperbit.

-  rdmult = (int)vp9_compute_rd_mult_based_on_qindex(cpi, ARNR_FILT_QINDEX);

-  if (rdmult < 1) rdmult = 1;

+  rdmult = vp9_compute_rd_mult_based_on_qindex(cpi, ARNR_FILT_QINDEX);

   set_error_per_bit(&cpi->td.mb, rdmult);

   vp9_initialize_me_consts(cpi, &cpi->td.mb, ARNR_FILT_QINDEX);