shithub: libvpx

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Add check_transition_to_still()

The behavior is the same as that of detect_transition_still,
only we void using cpi and twopass->stats_in

Change-Id: I07722c817d98d8e4991a0a883235a582db8b5c3c

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

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

@@ -1804,15 +1804,38 @@

                 (sr_decay_rate + ((1.0 - sr_decay_rate) * zero_motion_factor)));

 }

+static int get_show_idx(const TWO_PASS *twopass) {

+  return (int)(twopass->stats_in - twopass->stats_in_start);

+}

 // Function to test for a condition where a complex transition is followed

 // by a static section. For example in slide shows where there is a fade

 // between slides. This is to help with more optimal kf and gf positioning.

+static int check_transition_to_still(const FIRST_PASS_INFO *first_pass_info,

+                                     int show_idx, int still_interval) {

+  int j;

+  int num_frames = fps_get_num_frames(first_pass_info);

+  if (show_idx + still_interval > num_frames) {

+    return 0;

+  }

+

+  // Look ahead a few frames to see if static condition persists...

+  for (j = 0; j < still_interval; ++j) {

+    const FIRSTPASS_STATS *stats =

+        fps_get_frame_stats(first_pass_info, show_idx + j);

+    if (stats->pcnt_inter - stats->pcnt_motion < 0.999) break;

+  }

+

+  // Only if it does do we signal a transition to still.

+  return j == still_interval;

+}

+

 static int detect_transition_to_still(VP9_COMP *cpi, int frame_interval,

                                       int still_interval,

                                       double loop_decay_rate,

                                       double last_decay_rate) {

-  TWO_PASS *const twopass = &cpi->twopass;

+  const TWO_PASS *const twopass = &cpi->twopass;

   RATE_CONTROL *const rc = &cpi->rc;

+  int show_idx = get_show_idx(twopass);

   // Break clause to detect very still sections after motion

   // For example a static image after a fade or other transition

@@ -1819,18 +1842,8 @@

   // instead of a clean scene cut.

   if (frame_interval > rc->min_gf_interval && loop_decay_rate >= 0.999 &&

       last_decay_rate < 0.9) {

-    int j;

-

-    // Look ahead a few frames to see if static condition persists...

-    for (j = 0; j < still_interval; ++j) {

-      const FIRSTPASS_STATS *stats = &twopass->stats_in[j];

-      if (stats >= twopass->stats_in_end) break;

-

-      if (stats->pcnt_inter - stats->pcnt_motion < 0.999) break;

-    }

-

-    // Only if it does do we signal a transition to still.

-    return j == still_interval;

+    return check_transition_to_still(&twopass->first_pass_info, show_idx,

+                                     still_interval);

   }

   return 0;

@@ -2058,7 +2071,7 @@

   const FRAME_INFO *frame_info = &cpi->frame_info;

   TWO_PASS *const twopass = &cpi->twopass;

   const int avg_inter_frame_qindex = cpi->rc.avg_frame_qindex[INTER_FRAME];

-  int arf_show_idx = (int)(twopass->stats_in - twopass->stats_in_start);

+  int arf_show_idx = get_show_idx(twopass);

   return compute_arf_boost(frame_info, &twopass->first_pass_info, arf_show_idx,

                            f_frames, b_frames, avg_inter_frame_qindex);

 }

@@ -2608,10 +2621,14 @@

       // Break clause to detect very still sections after motion. For example,

       // a static image after a fade or other transition.

-      if (detect_transition_to_still(cpi, i, 5, loop_decay_rate,

-                                     last_loop_decay_rate)) {

-        allow_alt_ref = 0;

-        break;

+      if (i > rc->min_gf_interval && loop_decay_rate >= 0.999 &&

+          last_loop_decay_rate < 0.9) {

+        int still_interval = 5;

+        if (check_transition_to_still(first_pass_info, gf_start_show_idx + i,

+                                      still_interval)) {

+          allow_alt_ref = 0;

+          break;

+        }

       }

       // Update the accumulator for second ref error difference.

@@ -2666,7 +2683,7 @@

     const int avg_inter_frame_qindex = rc->avg_frame_qindex[INTER_FRAME];

     // TODO(angiebird): figure out why arf's location is assigned this way

     const int arf_show_idx =

-        VPXMIN(gf_start_show_idx + i + 1, first_pass_info->num_frames);

+        VPXMIN(gf_start_show_idx + i + 1, fps_get_num_frames(first_pass_info));

     // Calculate the boost for alt ref.

     rc->gfu_boost =

--- a/vp9/encoder/vp9_firstpass.h

+++ b/vp9/encoder/vp9_firstpass.h

@@ -158,6 +158,10 @@

   first_pass_info->num_frames = num_frames;

 }

+static INLINE int fps_get_num_frames(const FIRST_PASS_INFO *first_pass_info) {

+  return first_pass_info->num_frames;

+}

+

 static INLINE const FIRSTPASS_STATS *fps_get_frame_stats(

     const FIRST_PASS_INFO *first_pass_info, int show_idx) {

   if (show_idx >= first_pass_info->num_frames) {