shithub: libvpx

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vp9: Stop copying partition every a fixed number of frames.

Avoid quality loss when copying partition of superblock with large motions.
Maximum consecutively copied frames can be set (currently 5).

Change-Id: I11c30575514f02194c0f001444cf4021609e5049

--- a/vp9/encoder/vp9_encodeframe.c

+++ b/vp9/encoder/vp9_encodeframe.c

@@ -1043,19 +1043,25 @@

     // If the y_sad is small enough, copy the partition of the superblock in the

     // last frame to current frame only if the last frame is not a keyframe.

+    // Stop the copy every cpi->max_copied_frame to refresh the partition.

     // TODO(jianj) : tune the threshold.

     if (cpi->sf.copy_partition_flag && cpi->rc.frames_since_key > 1 &&

         segment_id == CR_SEGMENT_ID_BASE &&

         cpi->prev_segment_id[sb_offset] == CR_SEGMENT_ID_BASE &&

-        y_sad_last < cpi->vbp_threshold_copy) {

+        y_sad_last < cpi->vbp_threshold_copy &&

+        cpi->copied_frame_cnt[sb_offset] < cpi->max_copied_frame) {

       if (cpi->prev_partition != NULL) {

         copy_prev_partition(cpi, BLOCK_64X64, mi_row, mi_col);

         chroma_check(cpi, x, bsize, y_sad, is_key_frame);

+        cpi->copied_frame_cnt[sb_offset] += 1;

         memcpy(x->variance_low, &(cpi->prev_variance_low[sb_offset * 25]),

                sizeof(x->variance_low));

         return 0;

       }

     }

+    if (cpi->sf.copy_partition_flag &&

+        cpi->copied_frame_cnt[sb_offset] == cpi->max_copied_frame)

+      cpi->copied_frame_cnt[sb_offset] = 0;

   } else {

     d = VP9_VAR_OFFS;

     dp = 0;

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

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

@@ -459,6 +459,9 @@

   vpx_free(cpi->prev_variance_low);

   cpi->prev_variance_low = NULL;

+  vpx_free(cpi->copied_frame_cnt);

+  cpi->copied_frame_cnt = NULL;

+

   vp9_cyclic_refresh_free(cpi->cyclic_refresh);

   cpi->cyclic_refresh = NULL;

--- a/vp9/encoder/vp9_encoder.h

+++ b/vp9/encoder/vp9_encoder.h

@@ -639,6 +639,8 @@

   // This is for the last frame and is copied to the current frame

   // when partition copy happens.

   uint8_t *prev_variance_low;

+  uint8_t *copied_frame_cnt;

+  uint8_t max_copied_frame;

   LevelConstraint level_constraint;

 } VP9_COMP;

--- a/vp9/encoder/vp9_speed_features.c

+++ b/vp9/encoder/vp9_speed_features.c

@@ -502,8 +502,9 @@

     if (!cpi->use_svc && !cpi->resize_pending && !cpi->resize_state &&

         !cpi->external_resize && cpi->oxcf.resize_mode == RESIZE_NONE)

       sf->copy_partition_flag = 1;

+

     if (sf->copy_partition_flag) {

-      sf->use_source_sad = 1;

+      cpi->max_copied_frame = 5;

       if (cpi->prev_partition == NULL) {

         cpi->prev_partition = (BLOCK_SIZE *)vpx_calloc(

             cm->mi_stride * cm->mi_rows, sizeof(BLOCK_SIZE));

@@ -517,7 +518,12 @@

             (cm->mi_stride >> 3) * ((cm->mi_rows >> 3) + 1) * 25,

             sizeof(uint8_t));

       }

+      if (cpi->copied_frame_cnt == NULL) {

+        cpi->copied_frame_cnt = (uint8_t *)vpx_calloc(

+            (cm->mi_stride >> 3) * ((cm->mi_rows >> 3) + 1), sizeof(uint8_t));

+      }

     }

+

     sf->mv.subpel_force_stop = (content == VP9E_CONTENT_SCREEN) ? 3 : 2;

     if (content == VP9E_CONTENT_SCREEN) sf->lpf_pick = LPF_PICK_MINIMAL_LPF;

     // Only keep INTRA_DC mode for speed 8.