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FFmpegAndroid/app/src/main/cpp/yuv/yuv_converter.cpp

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//
// Created by xu fulong on 2022/7/9.
//
#include "yuv_converter.h"
#include <cstring>
// https://chromium.googlesource.com/libyuv/libyuv
// https://mymusing.co/bt601-yuv-to-rgb-conversion-color/
// https://www.color.org/chardata/rgb/rgb_registry.xalter
// BT.601 YUV to RGB
// R = 1.164 * (Y - 16) + 1.596 * (V - 128)
// G = 1.164 * (Y - 16) - 0.392 * (U - 128) - 0.812 * (V - 128)
// B = 1.164 * (Y - 16) + 2.016 * (U - 128)
// Y = 0.257 * R + 0.504 * G + 0.098 * B + 16
// U = -0.148 * R - 0.291 * G + 0.439 * B + 128
// V = 0.439 * R - 0.368 * G - 0.072 * B + 128
// BT.709 YUV to RGB
// R = 1.1644 * (Y - 16) + 1.7928 * (V - 128)
// G = 1.1644 * (Y - 16) - 0.2133 * (U - 128) - 0.533 * (V - 128)
// B = 1.1644 * (Y - 16) + 2.1124 * (U - 128)
// Y = 0.1826 * R + 0.6142 * G + 0.0620 * B + 16
// U = -0.1006 * R - 0.3386 * G + 0.4392 * B + 128
// V = 0.4392 * B - 0.3989 * G - 0.0403 * B + 128
// BT.2020 YUV to RGB
// R = Y - 16 + 1.4746 * (V - 128)
// G = Y - 16 - 0.1645 * (U - 128) - 0.5713 * (V - 128)
// B = Y - 16 + 1.881 * (U - 128)
// Y = 0.2627 * R + 0.6780 * G + 0.0593 * B + 16
// U = -0.1396 * R - 0.3604 * G + 0.5 * B + 128
// V = 0.5 * R - 0.4598 * G - 0.0402 * B + 128
static void rgba_to_yuv420p(int *argb, int8_t *yuv, int width, int height) {
int frameSize = width * height;
int index = 0;
int yIndex = 0;
int uIndex = frameSize;
int vIndex = frameSize * 5 / 4;
int R, G, B, Y, U, V;
for (int j = 0; j < height; j++) {
for (int i = 0; i < width; i++) {
R = (argb[index] & 0xff0000) >> 16;
G = (argb[index] & 0xff00) >> 8;
B = (argb[index] & 0xff);
// RGB to YUV algorithm
Y = ((66 * R + 129 * G + 25 * B + 128) >> 8) + 16;
// I420(YUV420p) -> YYYYYYYY UU VV
yuv[yIndex++] = (int8_t) Y;
if (j % 2 == 0 && i % 2 == 0) {
U = ((-38 * R - 74 * G + 112 * B + 128) >> 8) + 128;
V = ((112 * R - 94 * G - 18 * B + 128) >> 8) + 128;
yuv[uIndex++] = (int8_t) U;
yuv[vIndex++] = (int8_t) V;
}
index++;
}
}
}
static int yuv2argb(int y, int u, int v) {
#define max(a, b) ((a) > (b) ? (a) : (b))
int r, g, b;
r = y + (int) (1.402f * u);
g = y - (int) (0.344f * v + 0.714f * u);
b = y + (int) (1.772f * v);
r = r > 255 ? 255 : max(r, 0);
g = g > 255 ? 255 : max(g, 0);
b = b > 255 ? 255 : max(b, 0);
return 0xff000000 | (r << 16) | (g << 8) | b;
}
static void yuv420p_to_argb(int8_t *yuv, int *argb, int width, int height) {
int size = width * height;
int offset = size;
int u, v, y1, y2, y3, y4;
for (int i = 0, k = 0; i < size; i += 2, k += 2) {
y1 = yuv[i] & 0xff;
y2 = yuv[i + 1] & 0xff;
y3 = yuv[width + i] & 0xff;
y4 = yuv[width + i + 1] & 0xff;
u = yuv[offset + k] & 0xff;
v = yuv[offset + k + 1] & 0xff;
u = u - 128;
v = v - 128;
argb[i] = yuv2argb(y1, u, v);
argb[i + 1] = yuv2argb(y2, u, v);
argb[width + i] = yuv2argb(y3, u, v);
argb[width + i + 1] = yuv2argb(y4, u, v);
if (i != 0 && (i + 2) % width == 0)
i += width;
}
}
static void nv21_to_yuv420p(int8_t *dst, int8_t *src, int len) {
memcpy(dst, src, len); // y
for (int i = 0; i < len / 4; ++i) {
*(dst + len + i) = *(src + len + i * 2 + 1); // u
*(dst + len * 5 / 4 + i) = *(src + len + i * 2); // v
}
}
static void yuv420p_rotate90(int8_t *dst, int8_t *src, int width, int height) {
int n = 0;
int wh = width * height;
int half_width = width / 2;
int half_height = height / 2;
// y
for (int j = 0; j < width; j++) {
for (int i = height - 1; i >= 0; i--) {
dst[n++] = src[width * i + j];
}
}
// u
for (int i = 0; i < half_width; i++) {
for (int j = 1; j <= half_height; j++) {
dst[n++] = src[wh + ((half_height - j) * half_width + i)];
}
}
// v
for (int i = 0; i < half_width; i++) {
for (int j = 1; j <= half_height; j++) {
dst[n++] = src[wh + wh / 4 + ((half_height - j) * half_width + i)];
}
}
}
static void yuv420p_rotate180(int8_t *dst, int8_t *src, int width, int height) {
int n = 0;
int half_width = width / 2;
int half_height = height / 2;
// y
for (int j = height - 1; j >= 0; j--) {
for (int i = width; i > 0; i--) {
dst[n++] = src[width * j + i - 1];
}
}
// u
int offset = width * height;
for (int j = half_height - 1; j >= 0; j--) {
for (int i = half_width; i > 0; i--) {
dst[n++] = src[offset + half_width * j + i - 1];
}
}
// v
offset += half_width * half_height;
for (int j = half_height - 1; j >= 0; j--) {
for (int i = half_width; i > 0; i--) {
dst[n++] = src[offset + half_width * j + i - 1];
}
}
}
static void yuv420p_rotate270(int8_t *dst, int8_t *src, int width, int height) {
for (int j = 0; j < width; j++) {
for (int i = 1; i <= height; i++) {
*dest++ = *(src + i * width - j);
}
}
char *src_u = src + width * height;
for (int j = 0; j < width / 2; j++) {
for (int i = 1; i <= height / 2; i++) {
*dest++ = *(src_u + i * width / 2 - j);
}
}
char *src_v = src + width * height * 5 / 4;
for (int j = 0; j < width / 2; j++) {
for (int i = 1; i <= height / 2; i++) {
*dest++ = *(src_v + i * width / 2 - j);
}
}
}
static void yuv420p_rotate(int8_t *dst, int8_t *src, int width, int height, int degree) {
switch(degree) {
case 0:
memcpy(dst, src, width * height * 3 / 2);
break;
case 90:
yuv420p_rotate90(dst, src, width, height);
break;
case 180:
yuv420p_rotate180(dst, src, width, height);
break;
case 270:
yuv420p_rotate270(dst, src, width, height);
break;
default:
break;
}
}