shithub: libvpx

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Limit max arf boost and scale motion breakout for image size.

Added a cap on the maximum boost for an arf based on interval length.
Fixed bug where by the image size was not accounted for in determining
two of the motion breakout thresholds.

Overall small gains of 0.2-0.4% psnr but on large image format clips with
slow zooms the gain may be as much as 20% or more (e.g. in_to_tree
at 1080P)

Change-Id: Id0a47391203026742daa9c97afac5705fd8c4dfb

--- a/vp9/encoder/vp9_firstpass.c

+++ b/vp9/encoder/vp9_firstpass.c

@@ -2089,6 +2089,8 @@

   double mv_in_out_accumulator = 0.0;

   double abs_mv_in_out_accumulator = 0.0;

   double mv_ratio_accumulator_thresh;

+  double mv_in_out_thresh;

+  double abs_mv_in_out_thresh;

   unsigned int allow_alt_ref = is_altref_enabled(cpi);

   int f_boost = 0;

@@ -2132,6 +2134,8 @@

   // Motion breakout threshold for loop below depends on image size.

   mv_ratio_accumulator_thresh =

       (cpi->initial_height + cpi->initial_width) / 4.0;

+  mv_in_out_thresh = (cpi->initial_height + cpi->initial_width) / 300.0;

+  abs_mv_in_out_thresh = (cpi->initial_height + cpi->initial_width) / 200.0;

   // Set a maximum and minimum interval for the GF group.

   // If the image appears almost completely static we can extend beyond this.

@@ -2228,8 +2232,8 @@

             ((rc->frames_to_key - i) >= rc->min_gf_interval) &&

             (!flash_detected) &&

             ((mv_ratio_accumulator > mv_ratio_accumulator_thresh) ||

-             (abs_mv_in_out_accumulator > 3.0) ||

-             (mv_in_out_accumulator < -2.0) ||

+             (abs_mv_in_out_accumulator > abs_mv_in_out_thresh) ||

+             (mv_in_out_accumulator < -mv_in_out_thresh) ||

              ((boost_score - old_boost_score) < BOOST_BREAKOUT)))) {

       boost_score = old_boost_score;

       break;

@@ -2260,6 +2264,9 @@

     rc->gfu_boost = VPXMAX((int)boost_score, MIN_ARF_GF_BOOST);

     rc->source_alt_ref_pending = 0;

   }

+

+  // Limit maximum boost based on interval length.

+  rc->gfu_boost = VPXMIN((int)rc->gfu_boost, i * 200);

   // Set the interval until the next gf.

   rc->baseline_gf_interval = i - (is_key_frame || rc->source_alt_ref_pending);