Commit 2c560c3c authored by Linfeng Zhang's avatar Linfeng Zhang
Browse files

Specialize 4 to 3 frame scaling in C

Scale 3x3 block instead of 16x16 block in each loop. Disabled by
default.

Benefits:
1. Reduced number of different phase_scaler from 16 to 3.
   Optimization code will be smaller and faster.
2. Maximum phase_scaler drifting will be reduced from 5/16 to 1/24.
   (The drifting is 1/(3*16) in each step.)

BUG=webm:1419

Change-Id: I59a1f7496d89a1b090498c935d30cfcf1d0c282b
parent 3c700052
......@@ -20,8 +20,6 @@ void vp9_scale_and_extend_frame_c(const YV12_BUFFER_CONFIG *src,
INTERP_FILTER filter_type, int phase_scaler) {
const int src_w = src->y_crop_width;
const int src_h = src->y_crop_height;
const int dst_w = dst->y_crop_width;
const int dst_h = dst->y_crop_height;
const uint8_t *const srcs[3] = { src->y_buffer, src->u_buffer,
src->v_buffer };
const int src_strides[3] = { src->y_stride, src->uv_stride, src->uv_stride };
......@@ -30,22 +28,86 @@ void vp9_scale_and_extend_frame_c(const YV12_BUFFER_CONFIG *src,
const InterpKernel *const kernel = vp9_filter_kernels[filter_type];
int x, y, i;
for (i = 0; i < MAX_MB_PLANE; ++i) {
const int factor = (i == 0 || i == 3 ? 1 : 2);
const int src_stride = src_strides[i];
const int dst_stride = dst_strides[i];
for (y = 0; y < dst_h; y += 16) {
const int y_q4 = y * (16 / factor) * src_h / dst_h + phase_scaler;
for (x = 0; x < dst_w; x += 16) {
const int x_q4 = x * (16 / factor) * src_w / dst_w + phase_scaler;
const uint8_t *src_ptr = srcs[i] +
(y / factor) * src_h / dst_h * src_stride +
(x / factor) * src_w / dst_w;
uint8_t *dst_ptr = dsts[i] + (y / factor) * dst_stride + (x / factor);
#if 0
// TODO(linfengz): The 4:3 specialized C code is disabled by default since
// it's much slower than the general version which calls vpx_scaled_2d() even
// if vpx_scaled_2d() is not optimized. It will only be enabled as a reference
// for the platforms which have faster optimization.
if (4 * dst->y_crop_width == 3 * src_w &&
4 * dst->y_crop_height == 3 * src_h) {
// Specialize 4 to 3 scaling.
// Example pixel locations.
// (O: Original pixel. S: Scaled pixel. X: Overlapped pixel.)
// phase_scaler = 0 | phase_scaler = 8
// |
// X O S O S O X | O O O O O
// |
// |
// | S S S
// |
// |
// O O O O O | O O O O O
// |
// S S S S |
// |
// |
// | S S S
// O O O O O | O O O O O
// |
// |
// |
// S S S S |
// |
// O O O O O | O O O O O
// | S S S
// |
// |
// |
// |
// X O S O S O X | O O O O O
vpx_scaled_2d(src_ptr, src_stride, dst_ptr, dst_stride, kernel,
x_q4 & 0xf, 16 * src_w / dst_w, y_q4 & 0xf,
16 * src_h / dst_h, 16 / factor, 16 / factor);
const int dst_ws[3] = { dst->y_crop_width, dst->uv_crop_width,
dst->uv_crop_width };
const int dst_hs[3] = { dst->y_crop_height, dst->uv_crop_height,
dst->uv_crop_height };
for (i = 0; i < MAX_MB_PLANE; ++i) {
const int dst_w = dst_ws[i];
const int dst_h = dst_hs[i];
const int src_stride = src_strides[i];
const int dst_stride = dst_strides[i];
for (y = 0; y < dst_h; y += 3) {
for (x = 0; x < dst_w; x += 3) {
const uint8_t *src_ptr = srcs[i] + 4 * y / 3 * src_stride + 4 * x / 3;
uint8_t *dst_ptr = dsts[i] + y * dst_stride + x;
// Must call c function because its optimization doesn't support 3x3.
vpx_scaled_2d_c(src_ptr, src_stride, dst_ptr, dst_stride, kernel,
phase_scaler, 64 / 3, phase_scaler, 64 / 3, 3, 3);
}
}
}
} else
#endif
{
const int dst_w = dst->y_crop_width;
const int dst_h = dst->y_crop_height;
for (i = 0; i < MAX_MB_PLANE; ++i) {
const int factor = (i == 0 || i == 3 ? 1 : 2);
const int src_stride = src_strides[i];
const int dst_stride = dst_strides[i];
for (y = 0; y < dst_h; y += 16) {
const int y_q4 = y * (16 / factor) * src_h / dst_h + phase_scaler;
for (x = 0; x < dst_w; x += 16) {
const int x_q4 = x * (16 / factor) * src_w / dst_w + phase_scaler;
const uint8_t *src_ptr = srcs[i] +
(y / factor) * src_h / dst_h * src_stride +
(x / factor) * src_w / dst_w;
uint8_t *dst_ptr = dsts[i] + (y / factor) * dst_stride + (x / factor);
vpx_scaled_2d(src_ptr, src_stride, dst_ptr, dst_stride, kernel,
x_q4 & 0xf, 16 * src_w / dst_w, y_q4 & 0xf,
16 * src_h / dst_h, 16 / factor, 16 / factor);
}
}
}
}
......
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