commit eb939f45b8ffde47e160d545114d68ddd3606b90
author John Koleszar <jkoleszar@google.com> Sun Feb 24 20:55:14 2013 -0800
committer John Koleszar <jkoleszar@google.com> Tue Feb 26 23:54:23 2013 -0800
tree bfbd390adf5895b76d63fb7813b91fa77694f1c1
parent c7805395fd4aab2abadce9d34aaf07853cfc5e6d

Spatial resamping of ZEROMV predictors

This patch allows coding frames using references of different
resolution, in ZEROMV mode. For compound prediction, either
reference may be scaled.

To test, I use the resize_test and enable WRITE_RECON_BUFFER
in vp9_onyxd_if.c. It's also useful to apply this patch to
test/i420_video_source.h:

  --- a/test/i420_video_source.h
  +++ b/test/i420_video_source.h
  @@ -93,6 +93,7 @@ class I420VideoSource : public VideoSource {

     virtual void FillFrame() {
       // Read a frame from input_file.
  +    if (frame_ != 3)
       if (fread(img_->img_data, raw_sz_, 1, input_file_) == 0) {
         limit_ = frame_;
       }

This forces the frame that the resolution changes on to be coded
with no motion, only scaling, and improves the quality of the
result.

Change-Id: I1ee75d19a437ff801192f767fd02a36bcbd1d496

vp9/common/vp9_convolve.c

diff --git a/vp9/common/vp9_convolve.c b/vp9/common/vp9_convolve.c
index ac5d5cb..f1b5915 100644
--- a/vp9/common/vp9_convolve.c
+++ b/vp9/common/vp9_convolve.c
@@ -206,16 +206,25 @@
                        const int16_t *filter_x, int x_step_q4,
                        const int16_t *filter_y, int y_step_q4,
                        int w, int h, int taps) {
-  /* Fixed size intermediate buffer places limits on parameters. */
-  uint8_t temp[16 * 23];
+  /* Fixed size intermediate buffer places limits on parameters.
+   * Maximum intermediate_height is 39, for y_step_q4 == 32,
+   * h == 16, taps == 8.
+   */
+  uint8_t temp[16 * 39];
+  int intermediate_height = ((h * y_step_q4) >> 4) + taps - 1;
+
   assert(w <= 16);
   assert(h <= 16);
   assert(taps <= 8);
+  assert(y_step_q4 <= 32);
+
+  if (intermediate_height < h)
+    intermediate_height = h;
 
   convolve_horiz_c(src - src_stride * (taps / 2 - 1), src_stride,
                    temp, 16,
                    filter_x, x_step_q4, filter_y, y_step_q4,
-                   w, h + taps - 1, taps);
+                   w, intermediate_height, taps);
   convolve_vert_c(temp + 16 * (taps / 2 - 1), 16, dst, dst_stride,
                   filter_x, x_step_q4, filter_y, y_step_q4,
                   w, h, taps);
@@ -226,16 +235,25 @@
                            const int16_t *filter_x, int x_step_q4,
                            const int16_t *filter_y, int y_step_q4,
                            int w, int h, int taps) {
-  /* Fixed size intermediate buffer places limits on parameters. */
-  uint8_t temp[16 * 23];
+  /* Fixed size intermediate buffer places limits on parameters.
+   * Maximum intermediate_height is 39, for y_step_q4 == 32,
+   * h == 16, taps == 8.
+   */
+  uint8_t temp[16 * 39];
+  int intermediate_height = ((h * y_step_q4) >> 4) + taps - 1;
+
   assert(w <= 16);
   assert(h <= 16);
   assert(taps <= 8);
+  assert(y_step_q4 <= 32);
+
+  if (intermediate_height < h)
+    intermediate_height = h;
 
   convolve_horiz_c(src - src_stride * (taps / 2 - 1), src_stride,
                    temp, 16,
                    filter_x, x_step_q4, filter_y, y_step_q4,
-                   w, h + taps - 1, taps);
+                   w, intermediate_height, taps);
   convolve_avg_vert_c(temp + 16 * (taps / 2 - 1), 16, dst, dst_stride,
                       filter_x, x_step_q4, filter_y, y_step_q4,
                       w, h, taps);