shithub: libvpx

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vp9: Enable noise estimation on low res.

Set noise level to kLowLow for high motion low res clips.
Change the normalization in noise metric for low res.
Reduce the initial time-window for all resolutions.

Change-Id: Iaed39dbb50b205cd9c735dc5b84822304fb01987

--- a/vp9/encoder/vp9_noise_estimate.c

+++ b/vp9/encoder/vp9_noise_estimate.c

@@ -26,7 +26,7 @@

   ne->level = kLowLow;

   ne->value = 0;

   ne->count = 0;

-  ne->thresh = 100;

+  ne->thresh = 90;

   ne->last_w = 0;

   ne->last_h = 0;

   if (width * height >= 1920 * 1080) {

@@ -33,8 +33,10 @@

     ne->thresh = 200;

   } else if (width * height >= 1280 * 720) {

     ne->thresh = 140;

+  } else if (width * height >= 640 * 360) {

+    ne->thresh = 100;

   }

-  ne->num_frames_estimate = 20;

+  ne->num_frames_estimate = 15;

 }

 static int enable_noise_estimation(VP9_COMP *const cpi) {

@@ -41,10 +43,10 @@

 #if CONFIG_VP9_HIGHBITDEPTH

   if (cpi->common.use_highbitdepth) return 0;

 #endif

-// Enable noise estimation if denoising is on, but not for low resolutions.

+// Enable noise estimation if denoising is on.

 #if CONFIG_VP9_TEMPORAL_DENOISING

   if (cpi->oxcf.noise_sensitivity > 0 && denoise_svc(cpi) &&

-      cpi->common.width >= 640 && cpi->common.height >= 360)

+      cpi->common.width >= 320 && cpi->common.height >= 180)

     return 1;

 #endif

   // Only allow noise estimate under certain encoding mode.

@@ -97,6 +99,7 @@

 void vp9_update_noise_estimate(VP9_COMP *const cpi) {

   const VP9_COMMON *const cm = &cpi->common;

   NOISE_ESTIMATE *const ne = &cpi->noise_estimate;

+  const int low_res = (cm->width <= 352 && cm->height <= 288);

   // Estimate of noise level every frame_period frames.

   int frame_period = 8;

   int thresh_consec_zeromv = 6;

@@ -127,7 +130,7 @@

       ne->last_h = cm->height;

     }

     return;

-  } else if (cpi->rc.avg_frame_low_motion < 50) {

+  } else if (cpi->rc.avg_frame_low_motion < (low_res ? 70 : 50)) {

     // Force noise estimation to 0 and denoiser off if content has high motion.

     ne->level = kLowLow;

 #if CONFIG_VP9_TEMPORAL_DENOISING

@@ -210,7 +213,8 @@

               // Avoid blocks with high brightness and high spatial variance.

               if ((sse2 - spatial_variance) < thresh_sum_spatial &&

                   spatial_variance < thresh_spatial_var) {

-                avg_est += variance / ((spatial_variance >> 9) + 1);

+                avg_est += low_res ? variance >> 4

+                                   : variance / ((spatial_variance >> 9) + 1);

                 num_samples++;

               }

             }