shithub: libvpx

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Adjustment to scene detection and key frame.

For 1 pass vbr: use higher threshold on avg_sad
and force key frame under scene cut detection if
above the threshold. Allow it for speed >= 6 for now,
since it does not use the full nonrd_pickmode partition
(as in speed 5).

Improves quality somewhat on scene cut frames.
Neutral on overall metrics and fps for speed 6 on
ytlive set.

Change-Id: I12626f7627419ca14f9d0d249df86c7104438162

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

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

@@ -2276,6 +2276,7 @@

     int start_frame = 0;

     int frames_to_buffer = 1;

     int frame = 0;

+    int scene_cut_force_key_frame = 0;

     uint64_t avg_sad_current = 0;

     uint32_t min_thresh = 4000;

     float thresh = 8.0f;

@@ -2306,6 +2307,8 @@

         rc->high_source_sad = 1;

       else

         rc->high_source_sad = 0;

+      if (rc->high_source_sad && avg_sad_current > min_thresh << 1)

+        scene_cut_force_key_frame = 1;

       // Update recursive average for current frame.

       if (avg_sad_current > 0)

         rc->avg_source_sad[0] =

@@ -2366,6 +2369,8 @@

             rc->high_source_sad = 1;

           else

             rc->high_source_sad = 0;

+          if (rc->high_source_sad && avg_sad > min_thresh << 1)

+            scene_cut_force_key_frame = 1;

           if (avg_sad > 0 || cpi->oxcf.rc_mode == VPX_CBR)

             rc->avg_source_sad[0] = (3 * rc->avg_source_sad[0] + avg_sad) >> 2;

         } else {

@@ -2397,6 +2402,8 @@

         cpi->ext_refresh_frame_flags_pending == 0) {

       int target;

       cpi->refresh_golden_frame = 1;

+      if (cpi->oxcf.speed >= 6 && scene_cut_force_key_frame)

+        cm->frame_type = KEY_FRAME;

       rc->source_alt_ref_pending = 0;

       if (cpi->sf.use_altref_onepass && cpi->oxcf.enable_auto_arf)

         rc->source_alt_ref_pending = 1;