vp9-rtc: Move noise estimation to after scene change detection

This allows to use result from scene chage detection to exclude
the current frame from noise estimation analysis if the frame has
scene/ big content change (i.e., high_source_sad flag is set).

The behavior change for noise estimation may be small in practice,
since in the current code, a scene change would have blocks excluded
due to thresh_sum_diff, and the subsequent frames would also be mostly
excluded due to (past) non-zero motion vectors (until the
consec_zeromv > thresh_consec_zeromv is satisfied again).
But its better to completely exclude current frame if its a scene change.

Change-Id: Icd08bab7a8e1b994c7accced89697e0b2d7f50c5

diff --git a/vp9/encoder/vp9_encoder.c b/vp9/encoder/vp9_encoder.c
index 03e8ed674983f1af01e1d1b3deff52b9a342880b..ada1a3934351624ced28c121cf1b247b344805f4 100644 (file)
--- a/vp9/encoder/vp9_encoder.c
+++ b/vp9/encoder/vp9_encoder.c
@@ -3839,7 +3839,6 @@ static int encode_without_recode_loop(VP9_COMP *cpi, size_t *size,
   if (cpi->oxcf.noise_sensitivity > 0 && cpi->use_svc)
     vp9_denoiser_reset_on_first_frame(cpi);
 #endif
-  vp9_update_noise_estimate(cpi);
 
   // Scene detection is always used for VBR mode or screen-content case.
   // For other cases (e.g., CBR mode) use it for 5 <= speed < 8 for now
@@ -3871,6 +3870,8 @@ static int encode_without_recode_loop(VP9_COMP *cpi, size_t *size,
     }
   }
 
+  vp9_update_noise_estimate(cpi);
+
   // For 1 pass CBR, check if we are dropping this frame.
   // Never drop on key frame, if base layer is key for svc,
   // on scene change, or if superframe has layer sync.

diff --git a/vp9/encoder/vp9_noise_estimate.c b/vp9/encoder/vp9_noise_estimate.c
index b605003469feb9a5f1782c1204533b764acdb8cf..4bc81986e2a11bd4043538bbc2599a144d66cb9a 100644 (file)
--- a/vp9/encoder/vp9_noise_estimate.c
+++ b/vp9/encoder/vp9_noise_estimate.c
@@ -209,8 +209,11 @@ void vp9_update_noise_estimate(VP9_COMP *const cpi) {
           // Only consider blocks that are likely steady background. i.e, have
           // been encoded as zero/low motion x (= thresh_consec_zeromv) frames
           // in a row. consec_zero_mv[] defined for 8x8 blocks, so consider all
-          // 4 sub-blocks for 16x16 block. Also, avoid skin blocks.
-          if (frame_low_motion && consec_zeromv > thresh_consec_zeromv) {
+          // 4 sub-blocks for 16x16 block. And exclude this frame if
+          // high_source_sad is true (i.e., scene/content change).
+          if (frame_low_motion && consec_zeromv > thresh_consec_zeromv &&
+              !cpi->rc.high_source_sad &&
+              !cpi->svc.high_source_sad_superframe) {
             int is_skin = 0;
             if (cpi->use_skin_detection) {
               is_skin =