ref: 166d24d07ef4298aaf981e9b37d44b8d9655aa84
dir: /vpx_scale/generic/bicubic_scaler.c/
/*
* Copyright (c) 2010 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include <float.h>
#include <math.h>
#include <stdio.h>
#include "vpx_mem/vpx_mem.h"
#include "vpxscale_arbitrary.h"
#define FIXED_POINT
#define MAX_IN_WIDTH 800
#define MAX_IN_HEIGHT 600
#define MAX_OUT_WIDTH 800
#define MAX_OUT_HEIGHT 600
#define MAX_OUT_DIMENSION ((MAX_OUT_WIDTH > MAX_OUT_HEIGHT) ? \
MAX_OUT_WIDTH : MAX_OUT_HEIGHT)
BICUBIC_SCALER_STRUCT g_b_scaler;
static int g_first_time = 1;
#pragma DATA_SECTION(g_hbuf, "VP6_HEAP")
#pragma DATA_ALIGN (g_hbuf, 32);
unsigned char g_hbuf[MAX_OUT_DIMENSION];
#pragma DATA_SECTION(g_hbuf_uv, "VP6_HEAP")
#pragma DATA_ALIGN (g_hbuf_uv, 32);
unsigned char g_hbuf_uv[MAX_OUT_DIMENSION];
#ifdef FIXED_POINT
static int a_i = 0.6 * 65536;
#else
static float a = -0.6;
#endif
#ifdef FIXED_POINT
// 3 2
// C0 = a*t - a*t
//
static short c0_fixed(unsigned int t) {
// put t in Q16 notation
unsigned short v1, v2;
// Q16
v1 = (a_i * t) >> 16;
v1 = (v1 * t) >> 16;
// Q16
v2 = (a_i * t) >> 16;
v2 = (v2 * t) >> 16;
v2 = (v2 * t) >> 16;
// Q12
return -((v1 - v2) >> 4);
}
// 2 3
// C1 = a*t + (3-2*a)*t - (2-a)*t
//
static short c1_fixed(unsigned int t) {
unsigned short v1, v2, v3;
unsigned short two, three;
// Q16
v1 = (a_i * t) >> 16;
// Q13
two = 2 << 13;
v2 = two - (a_i >> 3);
v2 = (v2 * t) >> 16;
v2 = (v2 * t) >> 16;
v2 = (v2 * t) >> 16;
// Q13
three = 3 << 13;
v3 = three - (2 * (a_i >> 3));
v3 = (v3 * t) >> 16;
v3 = (v3 * t) >> 16;
// Q12
return (((v1 >> 3) - v2 + v3) >> 1);
}
// 2 3
// C2 = 1 - (3-a)*t + (2-a)*t
//
static short c2_fixed(unsigned int t) {
unsigned short v1, v2, v3;
unsigned short two, three;
// Q13
v1 = 1 << 13;
// Q13
three = 3 << 13;
v2 = three - (a_i >> 3);
v2 = (v2 * t) >> 16;
v2 = (v2 * t) >> 16;
// Q13
two = 2 << 13;
v3 = two - (a_i >> 3);
v3 = (v3 * t) >> 16;
v3 = (v3 * t) >> 16;
v3 = (v3 * t) >> 16;
// Q12
return (v1 - v2 + v3) >> 1;
}
// 2 3
// C3 = a*t - 2*a*t + a*t
//
static short c3_fixed(unsigned int t) {
int v1, v2, v3;
// Q16
v1 = (a_i * t) >> 16;
// Q15
v2 = 2 * (a_i >> 1);
v2 = (v2 * t) >> 16;
v2 = (v2 * t) >> 16;
// Q16
v3 = (a_i * t) >> 16;
v3 = (v3 * t) >> 16;
v3 = (v3 * t) >> 16;
// Q12
return ((v2 - (v1 >> 1) - (v3 >> 1)) >> 3);
}
#else
// 3 2
// C0 = -a*t + a*t
//
float C0(float t) {
return -a * t * t * t + a * t * t;
}
// 2 3
// C1 = -a*t + (2*a+3)*t - (a+2)*t
//
float C1(float t) {
return -(a + 2.0f) * t * t * t + (2.0f * a + 3.0f) * t * t - a * t;
}
// 2 3
// C2 = 1 - (a+3)*t + (a+2)*t
//
float C2(float t) {
return (a + 2.0f) * t * t * t - (a + 3.0f) * t * t + 1.0f;
}
// 2 3
// C3 = a*t - 2*a*t + a*t
//
float C3(float t) {
return a * t * t * t - 2.0f * a * t * t + a * t;
}
#endif
#if 0
int compare_real_fixed() {
int i, errors = 0;
float mult = 1.0 / 10000.0;
unsigned int fixed_mult = mult * 4294967296;// 65536;
unsigned int phase_offset_int;
float phase_offset_real;
for (i = 0; i < 10000; i++) {
int fixed0, fixed1, fixed2, fixed3, fixed_total;
int real0, real1, real2, real3, real_total;
phase_offset_real = (float)i * mult;
phase_offset_int = (fixed_mult * i) >> 16;
// phase_offset_int = phase_offset_real * 65536;
fixed0 = c0_fixed(phase_offset_int);
real0 = C0(phase_offset_real) * 4096.0;
if ((abs(fixed0) > (abs(real0) + 1)) || (abs(fixed0) < (abs(real0) - 1)))
errors++;
fixed1 = c1_fixed(phase_offset_int);
real1 = C1(phase_offset_real) * 4096.0;
if ((abs(fixed1) > (abs(real1) + 1)) || (abs(fixed1) < (abs(real1) - 1)))
errors++;
fixed2 = c2_fixed(phase_offset_int);
real2 = C2(phase_offset_real) * 4096.0;
if ((abs(fixed2) > (abs(real2) + 1)) || (abs(fixed2) < (abs(real2) - 1)))
errors++;
fixed3 = c3_fixed(phase_offset_int);
real3 = C3(phase_offset_real) * 4096.0;
if ((abs(fixed3) > (abs(real3) + 1)) || (abs(fixed3) < (abs(real3) - 1)))
errors++;
fixed_total = fixed0 + fixed1 + fixed2 + fixed3;
real_total = real0 + real1 + real2 + real3;
if ((fixed_total > 4097) || (fixed_total < 4094))
errors++;
if ((real_total > 4097) || (real_total < 4095))
errors++;
}
return errors;
}
#endif
// Find greatest common denominator between two integers. Method used here is
// slow compared to Euclid's algorithm, but does not require any division.
int gcd(int a, int b) {
// Problem with this algorithm is that if a or b = 0 this function
// will never exit. Don't want to return 0 because any computation
// that was based on a common denoninator and tried to reduce by
// dividing by 0 would fail. Best solution that could be thought of
// would to be fail by returing a 1;
if (a <= 0 || b <= 0)
return 1;
while (a != b) {
if (b > a)
b = b - a;
else {
int tmp = a;// swap large and
a = b; // small
b = tmp;
}
}
return b;
}
void bicubic_coefficient_init() {
vpx_memset(&g_b_scaler, 0, sizeof(BICUBIC_SCALER_STRUCT));
g_first_time = 0;
}
void bicubic_coefficient_destroy() {
if (!g_first_time) {
vpx_free(g_b_scaler.l_w);
vpx_free(g_b_scaler.l_h);
vpx_free(g_b_scaler.l_h_uv);
vpx_free(g_b_scaler.c_w);
vpx_free(g_b_scaler.c_h);
vpx_free(g_b_scaler.c_h_uv);
vpx_memset(&g_b_scaler, 0, sizeof(BICUBIC_SCALER_STRUCT));
}
}
// Create the coeffients that will be used for the cubic interpolation.
// Because scaling does not have to be equal in the vertical and horizontal
// regimes the phase offsets will be different. There are 4 coefficents
// for each point, two on each side. The layout is that there are the
// 4 coefficents for each phase in the array and then the next phase.
int bicubic_coefficient_setup(int in_width, int in_height, int out_width, int out_height) {
int i;
#ifdef FIXED_POINT
int phase_offset_int;
unsigned int fixed_mult;
int product_val = 0;
#else
float phase_offset;
#endif
int gcd_w, gcd_h, gcd_h_uv, d_w, d_h, d_h_uv;
if (g_first_time)
bicubic_coefficient_init();
// check to see if the coefficents have already been set up correctly
if ((in_width == g_b_scaler.in_width) && (in_height == g_b_scaler.in_height)
&& (out_width == g_b_scaler.out_width) && (out_height == g_b_scaler.out_height))
return 0;
g_b_scaler.in_width = in_width;
g_b_scaler.in_height = in_height;
g_b_scaler.out_width = out_width;
g_b_scaler.out_height = out_height;
// Don't want to allow crazy scaling, just try and prevent a catastrophic
// failure here. Want to fail after setting the member functions so if
// if the scaler is called the member functions will not scale.
if (out_width <= 0 || out_height <= 0)
return -1;
// reduce in/out width and height ratios using the gcd
gcd_w = gcd(out_width, in_width);
gcd_h = gcd(out_height, in_height);
gcd_h_uv = gcd(out_height, in_height / 2);
// the numerator width and height are to be saved in
// globals so they can be used during the scaling process
// without having to be recalculated.
g_b_scaler.nw = out_width / gcd_w;
d_w = in_width / gcd_w;
g_b_scaler.nh = out_height / gcd_h;
d_h = in_height / gcd_h;
g_b_scaler.nh_uv = out_height / gcd_h_uv;
d_h_uv = (in_height / 2) / gcd_h_uv;
// allocate memory for the coefficents
vpx_free(g_b_scaler.l_w);
vpx_free(g_b_scaler.l_h);
vpx_free(g_b_scaler.l_h_uv);
g_b_scaler.l_w = (short *)vpx_memalign(32, out_width * 2);
g_b_scaler.l_h = (short *)vpx_memalign(32, out_height * 2);
g_b_scaler.l_h_uv = (short *)vpx_memalign(32, out_height * 2);
vpx_free(g_b_scaler.c_w);
vpx_free(g_b_scaler.c_h);
vpx_free(g_b_scaler.c_h_uv);
g_b_scaler.c_w = (short *)vpx_memalign(32, g_b_scaler.nw * 4 * 2);
g_b_scaler.c_h = (short *)vpx_memalign(32, g_b_scaler.nh * 4 * 2);
g_b_scaler.c_h_uv = (short *)vpx_memalign(32, g_b_scaler.nh_uv * 4 * 2);
g_b_scaler.hbuf = g_hbuf;
g_b_scaler.hbuf_uv = g_hbuf_uv;
// Set up polyphase filter taps. This needs to be done before
// the scaling because of the floating point math required. The
// coefficients are multiplied by 2^12 so that fixed point math
// can be used in the main scaling loop.
#ifdef FIXED_POINT
fixed_mult = (1.0 / (float)g_b_scaler.nw) * 4294967296;
product_val = 0;
for (i = 0; i < g_b_scaler.nw; i++) {
if (product_val > g_b_scaler.nw)
product_val -= g_b_scaler.nw;
phase_offset_int = (fixed_mult * product_val) >> 16;
g_b_scaler.c_w[i * 4] = c3_fixed(phase_offset_int);
g_b_scaler.c_w[i * 4 + 1] = c2_fixed(phase_offset_int);
g_b_scaler.c_w[i * 4 + 2] = c1_fixed(phase_offset_int);
g_b_scaler.c_w[i * 4 + 3] = c0_fixed(phase_offset_int);
product_val += d_w;
}
fixed_mult = (1.0 / (float)g_b_scaler.nh) * 4294967296;
product_val = 0;
for (i = 0; i < g_b_scaler.nh; i++) {
if (product_val > g_b_scaler.nh)
product_val -= g_b_scaler.nh;
phase_offset_int = (fixed_mult * product_val) >> 16;
g_b_scaler.c_h[i * 4] = c0_fixed(phase_offset_int);
g_b_scaler.c_h[i * 4 + 1] = c1_fixed(phase_offset_int);
g_b_scaler.c_h[i * 4 + 2] = c2_fixed(phase_offset_int);
g_b_scaler.c_h[i * 4 + 3] = c3_fixed(phase_offset_int);
product_val += d_h;
}
fixed_mult = (1.0 / (float)g_b_scaler.nh_uv) * 4294967296;
product_val = 0;
for (i = 0; i < g_b_scaler.nh_uv; i++) {
if (product_val > g_b_scaler.nh_uv)
product_val -= g_b_scaler.nh_uv;
phase_offset_int = (fixed_mult * product_val) >> 16;
g_b_scaler.c_h_uv[i * 4] = c0_fixed(phase_offset_int);
g_b_scaler.c_h_uv[i * 4 + 1] = c1_fixed(phase_offset_int);
g_b_scaler.c_h_uv[i * 4 + 2] = c2_fixed(phase_offset_int);
g_b_scaler.c_h_uv[i * 4 + 3] = c3_fixed(phase_offset_int);
product_val += d_h_uv;
}
#else
for (i = 0; i < g_nw; i++) {
phase_offset = (float)((i * d_w) % g_nw) / (float)g_nw;
g_c_w[i * 4] = (C3(phase_offset) * 4096.0);
g_c_w[i * 4 + 1] = (C2(phase_offset) * 4096.0);
g_c_w[i * 4 + 2] = (C1(phase_offset) * 4096.0);
g_c_w[i * 4 + 3] = (C0(phase_offset) * 4096.0);
}
for (i = 0; i < g_nh; i++) {
phase_offset = (float)((i * d_h) % g_nh) / (float)g_nh;
g_c_h[i * 4] = (C0(phase_offset) * 4096.0);
g_c_h[i * 4 + 1] = (C1(phase_offset) * 4096.0);
g_c_h[i * 4 + 2] = (C2(phase_offset) * 4096.0);
g_c_h[i * 4 + 3] = (C3(phase_offset) * 4096.0);
}
for (i = 0; i < g_nh_uv; i++) {
phase_offset = (float)((i * d_h_uv) % g_nh_uv) / (float)g_nh_uv;
g_c_h_uv[i * 4] = (C0(phase_offset) * 4096.0);
g_c_h_uv[i * 4 + 1] = (C1(phase_offset) * 4096.0);
g_c_h_uv[i * 4 + 2] = (C2(phase_offset) * 4096.0);
g_c_h_uv[i * 4 + 3] = (C3(phase_offset) * 4096.0);
}
#endif
// Create an array that corresponds input lines to output lines.
// This doesn't require floating point math, but it does require
// a division and because hardware division is not present that
// is a call.
for (i = 0; i < out_width; i++) {
g_b_scaler.l_w[i] = (i * d_w) / g_b_scaler.nw;
if ((g_b_scaler.l_w[i] + 2) <= in_width)
g_b_scaler.max_usable_out_width = i;
}
for (i = 0; i < out_height + 1; i++) {
g_b_scaler.l_h[i] = (i * d_h) / g_b_scaler.nh;
g_b_scaler.l_h_uv[i] = (i * d_h_uv) / g_b_scaler.nh_uv;
}
return 0;
}
int bicubic_scale(int in_width, int in_height, int in_stride,
int out_width, int out_height, int out_stride,
unsigned char *input_image, unsigned char *output_image) {
short *RESTRICT l_w, * RESTRICT l_h;
short *RESTRICT c_w, * RESTRICT c_h;
unsigned char *RESTRICT ip, * RESTRICT op;
unsigned char *RESTRICT hbuf;
int h, w, lw, lh;
int temp_sum;
int phase_offset_w, phase_offset_h;
c_w = g_b_scaler.c_w;
c_h = g_b_scaler.c_h;
op = output_image;
l_w = g_b_scaler.l_w;
l_h = g_b_scaler.l_h;
phase_offset_h = 0;
for (h = 0; h < out_height; h++) {
// select the row to work on
lh = l_h[h];
ip = input_image + (in_stride * lh);
// vp8_filter the row vertically into an temporary buffer.
// If the phase offset == 0 then all the multiplication
// is going to result in the output equalling the input.
// So instead point the temporary buffer to the input.
// Also handle the boundry condition of not being able to
// filter that last lines.
if (phase_offset_h && (lh < in_height - 2)) {
hbuf = g_b_scaler.hbuf;
for (w = 0; w < in_width; w++) {
temp_sum = c_h[phase_offset_h * 4 + 3] * ip[w - in_stride];
temp_sum += c_h[phase_offset_h * 4 + 2] * ip[w];
temp_sum += c_h[phase_offset_h * 4 + 1] * ip[w + in_stride];
temp_sum += c_h[phase_offset_h * 4] * ip[w + 2 * in_stride];
hbuf[w] = temp_sum >> 12;
}
} else
hbuf = ip;
// increase the phase offset for the next time around.
if (++phase_offset_h >= g_b_scaler.nh)
phase_offset_h = 0;
// now filter and expand it horizontally into the final
// output buffer
phase_offset_w = 0;
for (w = 0; w < out_width; w++) {
// get the index to use to expand the image
lw = l_w[w];
temp_sum = c_w[phase_offset_w * 4] * hbuf[lw - 1];
temp_sum += c_w[phase_offset_w * 4 + 1] * hbuf[lw];
temp_sum += c_w[phase_offset_w * 4 + 2] * hbuf[lw + 1];
temp_sum += c_w[phase_offset_w * 4 + 3] * hbuf[lw + 2];
temp_sum = temp_sum >> 12;
if (++phase_offset_w >= g_b_scaler.nw)
phase_offset_w = 0;
// boundry conditions
if ((lw + 2) >= in_width)
temp_sum = hbuf[lw];
if (lw == 0)
temp_sum = hbuf[0];
op[w] = temp_sum;
}
op += out_stride;
}
return 0;
}
void bicubic_scale_frame_reset() {
g_b_scaler.out_width = 0;
g_b_scaler.out_height = 0;
}
void bicubic_scale_frame(YV12_BUFFER_CONFIG *src, YV12_BUFFER_CONFIG *dst,
int new_width, int new_height) {
dst->y_width = new_width;
dst->y_height = new_height;
dst->uv_width = new_width / 2;
dst->uv_height = new_height / 2;
dst->y_stride = dst->y_width;
dst->uv_stride = dst->uv_width;
bicubic_scale(src->y_width, src->y_height, src->y_stride,
new_width, new_height, dst->y_stride,
src->y_buffer, dst->y_buffer);
bicubic_scale(src->uv_width, src->uv_height, src->uv_stride,
new_width / 2, new_height / 2, dst->uv_stride,
src->u_buffer, dst->u_buffer);
bicubic_scale(src->uv_width, src->uv_height, src->uv_stride,
new_width / 2, new_height / 2, dst->uv_stride,
src->v_buffer, dst->v_buffer);
}