VP9_resizing: add limitation to the downsacling resolution.

Width and height of downscaling resolution should not be lower
than min_width and min_height which can be set as needed, both
are 180 for now.

Change-Id: I34d06704ea51affbdd814246e22ee8d41d991f00

diff --git a/vp9/encoder/vp9_ratectrl.c b/vp9/encoder/vp9_ratectrl.c
index d70068570e8e31ae4a42e7bbe3c5e17981fb99b6..9905d9e789686a6b708fdc1a8997cad44ad670c5 100644 (file)
--- a/vp9/encoder/vp9_ratectrl.c
+++ b/vp9/encoder/vp9_ratectrl.c
@@ -1835,6 +1835,9 @@ int vp9_resize_one_pass_cbr(VP9_COMP *cpi) {
   RESIZE_ACTION resize_action = NO_RESIZE;
   int avg_qp_thr1 = 70;
   int avg_qp_thr2 = 50;
+  int min_width = 180;
+  int min_height = 180;
+  int down_size_on = 1;
   cpi->resize_scale_num = 1;
   cpi->resize_scale_den = 1;
   // Don't resize on key frame; reset the counters on key frame.
@@ -1843,6 +1846,21 @@ int vp9_resize_one_pass_cbr(VP9_COMP *cpi) {
     cpi->resize_count = 0;
     return 0;
   }
+  // Check current frame reslution to avoid generating frames smaller than
+  // the minimum resolution.
+  if (ONEHALFONLY_RESIZE) {
+    if ((cm->width >> 1) < min_width || (cm->height >> 1) < min_height)
+      down_size_on = 0;
+  } else {
+    if (cpi->resize_state == ORIG &&
+        (cm->width * 3 / 4 < min_width ||
+         cm->height * 3 / 4 < min_height))
+      return 0;
+    else if (cpi->resize_state == THREE_QUARTER &&
+             ((cpi->oxcf.width >> 1) < min_width ||
+              (cpi->oxcf.height >> 1) < min_height))
+      down_size_on = 0;
+  }
 
 #if CONFIG_VP9_TEMPORAL_DENOISING
   // If denoiser is on, apply a smaller qp threshold.
@@ -1869,7 +1887,7 @@ int vp9_resize_one_pass_cbr(VP9_COMP *cpi) {
       // down state, i.e. 1/2 or 3/4 of original resolution.
       // Currently, use a flag to turn 3/4 resizing feature on/off.
       if (cpi->resize_buffer_underflow > (cpi->resize_count >> 2)) {
-        if (cpi->resize_state == THREE_QUARTER) {
+        if (cpi->resize_state == THREE_QUARTER && down_size_on) {
           resize_action = DOWN_ONEHALF;
           cpi->resize_state = ONE_HALF;
         } else if (cpi->resize_state == ORIG) {