shithub: libvpx

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Increase active best quality linearly

The ARF frames in last few gf intervals, would be
used as a reference by fewer ARF frames in the same
kf interval. Also, the ARF frames in the last GF
group would not be used as a reference in future.
Hence the active best quality for these ARF frames
is increased based on their temporal distance from
the next key frame.

Change-Id: Ice7eaa8a25384104b1d9cc021eec588c03053fc2

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

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

@@ -2642,6 +2642,17 @@

     rc->source_alt_ref_pending = 0;

   }

+#define LAST_ALR_ACTIVE_BEST_QUALITY_ADJUSTMENT_FACTOR 0.2

+  rc->arf_active_best_quality_adjustment_factor = 1.0;

+  if (rc->source_alt_ref_pending && !is_lossless_requested(&cpi->oxcf) &&

+      rc->frames_to_key <= rc->arf_active_best_quality_adjustment_window) {

+    rc->arf_active_best_quality_adjustment_factor =

+        LAST_ALR_ACTIVE_BEST_QUALITY_ADJUSTMENT_FACTOR +

+        (1.0 - LAST_ALR_ACTIVE_BEST_QUALITY_ADJUSTMENT_FACTOR) *

+            (rc->frames_to_key - i) /

+            VPXMAX(1, (rc->arf_active_best_quality_adjustment_window - i));

+  }

+

 #ifdef AGGRESSIVE_VBR

   // Limit maximum boost based on interval length.

   rc->gfu_boost = VPXMIN((int)rc->gfu_boost, i * 140);

@@ -3190,6 +3201,11 @@

     // Default to normal-sized frame on keyframes.

     cpi->rc.next_frame_size_selector = UNSCALED;

   }

+#define ARF_ACTIVE_BEST_QUALITY_ADJUSTMENT_WINDOW_SIZE 64

+  // TODO(ravi.chaudhary@ittiam.com): Experiment without the below min

+  // condition. This might be helpful for small key frame intervals.

+  rc->arf_active_best_quality_adjustment_window =

+      VPXMIN(ARF_ACTIVE_BEST_QUALITY_ADJUSTMENT_WINDOW_SIZE, rc->frames_to_key);

 }

 static int is_skippable_frame(const VP9_COMP *cpi) {

--- a/vp9/encoder/vp9_ratectrl.c

+++ b/vp9/encoder/vp9_ratectrl.c

@@ -437,6 +437,7 @@

   rc->last_post_encode_dropped_scene_change = 0;

   rc->use_post_encode_drop = 0;

   rc->ext_use_post_encode_drop = 0;

+  rc->arf_active_best_quality_adjustment_factor = 1.0;

 }

 static int check_buffer_above_thresh(VP9_COMP *cpi, int drop_mark) {

@@ -1417,6 +1418,8 @@

   int active_worst_quality = cpi->twopass.active_worst_quality;

   int q;

   int *inter_minq;

+  int arf_active_best_quality_adjustment, arf_active_best_quality_max;

+  int *arfgf_high_motion_minq;

   const int boost_frame =

       !rc->is_src_frame_alt_ref &&

       (cpi->refresh_golden_frame || cpi->refresh_alt_ref_frame);

@@ -1443,6 +1446,14 @@

       if (q < cq_level) q = cq_level;

     }

     active_best_quality = get_gf_active_quality(cpi, q, cm->bit_depth);

+

+    ASSIGN_MINQ_TABLE(cm->bit_depth, arfgf_high_motion_minq);

+    arf_active_best_quality_max = arfgf_high_motion_minq[q];

+    arf_active_best_quality_adjustment =

+        arf_active_best_quality_max - active_best_quality;

+    active_best_quality = arf_active_best_quality_max -

+                          (int)(arf_active_best_quality_adjustment *

+                                rc->arf_active_best_quality_adjustment_factor);

     // Modify best quality for second level arfs. For mode VPX_Q this

     // becomes the baseline frame q.

--- a/vp9/encoder/vp9_ratectrl.h

+++ b/vp9/encoder/vp9_ratectrl.h

@@ -197,6 +197,8 @@

   int ext_use_post_encode_drop;

   int damped_adjustment[RATE_FACTOR_LEVELS];

+  double arf_active_best_quality_adjustment_factor;

+  int arf_active_best_quality_adjustment_window;

 } RATE_CONTROL;

 struct VP9_COMP;