libyuv
libyuv 是 Google 开源的实现各种 YUV 与 RGB 之间相互转换、旋转、缩放等的库。它是跨平台的，可在 Windows、Linux、Mac、Android 等操作系统，x86、x64、arm 架构上进行编译运行，支持 SSE、AVX、NEON 等 SIMD 指令加速。
准备工作
一张图片
下载 rainbow-700x700.bmp BMP 图片 或者 自己准备一张图片（知道分辨率，如：700x700）
image-demo-rainbow.png
FFmpeg 工具包
根据自己的系统，下载 FFmpeg Static 工具包。
得到所需的 yuv420p 文件
将上面准备的图片转换成 YUV420P 格式：
ffmpeg -i rainbow.bmp -video_size 700x700 -pix_fmt yuv420p rainbow-yuv420p.yuv
查看 YUV 文件
ffplay -f rawvideo -pixel_format yuv420p -video_size 700x700 rainbow-yuv420p.yuv
libyuv 操作 YUV
YUV 裁剪
libyuv-yuv420p-clip.jpg
[rainbow-yuv420p.yuv] -> [rainbow-yuv420p-clip-x-y.yuv]
#include <stdio.h>
#include <stdint.h>
#include "libyuv.h"
void clip(uint8_t *srcYuvData, uint8_t *dstYuvData, int width, int height, int cropX, int cropY, int cropWidth, int cropHeight) {
ConvertToI420(
srcYuvData,
width*height*3/2,
dstYuvData,
cropWidth,
dstYuvData+cropWidth*cropHeight,
(cropWidth+1)/2,
dstYuvData+cropWidth*cropHeight+((cropWidth+1)/2)*((cropHeight+1)/2),
(cropWidth+1)/2,
cropX,
cropY,
width,
height,
cropWidth,
cropHeight,
kRotate0,
FOURCC_YU12);
}
int main() {
uint32_t width = 700, height = 700;
uint32_t clipWidth = 200, clipHeight = 200;
uint8_t YUV[width*height*3/2];
uint8_t YUV_CLIP[clipWidth*clipHeight*3/2];
FILE *yuv420pFile = fopen("/Users/staff/Desktop/rainbow-yuv420p.yuv", "rb");
fread(YUV, sizeof(YUV), 1, yuv420pFile);
clip(YUV, YUV_CLIP, width, height, 0, 0, clipWidth, clipHeight);
FILE *yuvClipFile = fopen("/Users/staff/Desktop/rainbow-yuv420p-clip-0-0.yuv", "wb");
fwrite(YUV_CLIP, sizeof(YUV_CLIP), 1, yuvClipFile);
fclose(yuvClipFile);
fclose(yuv420pFile);
return 0;
}
YUV 缩放
libyuv-yuv420p-scale.jpg
[rainbow-yuv420p.yuv] -> [rainbow-yuv420p-scale-X.yuv]
#include <stdio.h>
#include <stdint.h>
#include "libyuv.h"
void scale(uint8_t *srcYuvData, uint8_t *dstYuvData, int width, int height, int dstWidth, int dstHeight) {
I420Scale(
srcYuvData,
width,
srcYuvData+width*height,
(width+1)/2,
srcYuvData+width*height+((width+1)/2)*((height+1)/2),
(width+1)/2,
width,
height,
dstYuvData,
dstWidth,
dstYuvData+dstWidth*dstWidth,
(dstWidth+1)/2,
dstYuvData+dstWidth*dstHeight+((dstWidth+1)/2)*((dstHeight+1)/2),
(dstWidth+1)/2,
dstWidth,
dstHeight,
kFilterNone
);
}
int main() {
uint32_t width = 700, height = 700;
uint32_t dstWidth = 100, dstHeight = 100;
uint8_t YUV[width*height*3/2];
uint8_t YUV_SCALE[dstWidth*dstHeight*3/2];
FILE *yuv420pFile = fopen("/Users/staff/Desktop/rainbow-yuv420p.yuv", "rb");
fread(YUV, sizeof(YUV), 1, yuv420pFile);
scale(YUV, YUV_SCALE, width, height, dstWidth, dstHeight);
FILE *yuvScaleFile = fopen("/Users/staff/Desktop/rainbow-yuv420p-scale-6.yuv", "wb");
fwrite(YUV_SCALE, sizeof(YUV_SCALE), 1, yuvScaleFile);
fclose(yuvScaleFile);
fclose(yuv420pFile);
return 0;
}
YUV 旋转
libyuv-yuv420p-rotation.jpg
[rainbow-yuv420p.yuv] -> [rainbow-yuv420p-rotation-90.yuv]
#include <stdio.h>
#include <stdint.h>
#include "libyuv.h"
void rotation(uint8_t *srcYuvData, uint8_t *dstYuvData, int width, int height) {
I420Rotate(
srcYuvData,
width,
srcYuvData+width*height,
(width+1)/2,
srcYuvData+width*height+((width+1)/2)*((height+1)/2),
(width+1)/2,
dstYuvData,
width,
dstYuvData+width*height,
(width+1)/2,
dstYuvData+width*height+((width+1)/2)*((height+1)/2),
(width+1)/2,
width,
height,
kRotate90
);
}
int main() {
uint32_t width = 700, height = 700;
uint8_t YUV[width*height*3/2];
uint8_t YUV_ROTATION[width*height*3/2];
FILE *yuv420pFile = fopen("/Users/staff/Desktop/rainbow-yuv420p.yuv", "rb");
fread(YUV, sizeof(YUV), 1, yuv420pFile);
rotation(YUV, YUV_ROTATION, width, height);
FILE *yuvRotationFile = fopen("/Users/staff/Desktop/rainbow-yuv420p-rotation-90.yuv", "wb");
fwrite(YUV_ROTATION, sizeof(YUV_ROTATION), 1, yuvRotationFile);
fclose(yuvRotationFile);
fclose(yuv420pFile);
return 0;
}
YUV 镜像
libyuv-yuv420p-mirror.jpg
[rainbow-yuv420p-rotation-90.yuv] -> [rainbow-yuv420p-rotation-90-mirror.yuv]
#include <stdio.h>
#include <stdint.h>
#include "libyuv.h"
void mirror(uint8_t *srcYuvData, uint8_t *dstYuvData, int width, int height) {
I420Mirror(
srcYuvData,
width,
srcYuvData+width*height,
(width+1)/2,
srcYuvData+width*height+((width+1)/2)*((height+1)/2),
(width+1)/2,
dstYuvData,
width,
dstYuvData+width*height,
(width+1)/2,
dstYuvData+width*height+((width+1)/2)*((height+1)/2),
(width+1)/2,
width,
height
);
}
int main() {
uint32_t width = 700, height = 700;
uint8_t YUV[width*height*3/2];
uint8_t YUV_MIRROR[width*height*3/2];
FILE *yuv420pFile = fopen("/Users/staff/Desktop/rainbow-yuv420p-rotation-90.yuv", "rb");
fread(YUV, sizeof(YUV), 1, yuv420pFile);
mirror(YUV, YUV_MIRROR, width, height);
FILE *yuvMirrorFile = fopen("/Users/staff/Desktop/rainbow-yuv420p-rotation-90-mirror.yuv", "wb");
fwrite(YUV_MIRROR, sizeof(YUV_MIRROR), 1, yuvMirrorFile);
fclose(yuvMirrorFile);
fclose(yuv420pFile);
return 0;
}
YUV 混合
libyuv-yuv420p-blend.jpg
[rainbow-yuv420p.yuv] -> [rainbow-yuv420p-blend.yuv]
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include "libyuv.h"
void blend(uint8_t *srcYuvData, uint8_t *dstYuvData, int width, int height) {
uint8_t YUV_ROTATION[width*height*3/2];
I420Rotate(
srcYuvData,
width,
srcYuvData+width*height,
(width+1)/2,
srcYuvData+width*height+((width+1)/2)*((height+1)/2),
(width+1)/2,
YUV_ROTATION,
width,
YUV_ROTATION+width*height,
(width+1)/2,
YUV_ROTATION+width*height+((width+1)/2)*((height+1)/2),
(width+1)/2,
width,
height,
kRotate90
);
// 透明度
uint8_t alpha[width*height];
memset(alpha, 0X88, width*height);
I420Blend(
srcYuvData,
width,
srcYuvData+width*height,
(width+1)/2,
srcYuvData+width*height+((width+1)/2)*((height+1)/2),
(width+1)/2,
YUV_ROTATION,
width,
YUV_ROTATION+width*height,
(width+1)/2,
YUV_ROTATION+width*height+((width+1)/2)*((height+1)/2),
(width+1)/2,
alpha,
width,
dstYuvData,
width,
dstYuvData+width*height,
(width+1)/2,
dstYuvData+width*height+((width+1)/2)*((height+1)/2),
(width+1)/2,
width,
height
);
}
int main() {
uint32_t width = 700, height = 700;
uint8_t YUV[width*height*3/2];
uint8_t YUV_BLEND[width*height*3/2];
FILE *yuv420pFile = fopen("/Users/staff/Desktop/rainbow-yuv420p.yuv", "rb");
fread(YUV, sizeof(YUV), 1, yuv420pFile);
blend(YUV, YUV_BLEND, width, height);
FILE *yuvBlendFile = fopen("/Users/staff/Desktop/rainbow-yuv420p-blend.yuv", "wb");
fwrite(YUV_BLEND, sizeof(YUV_BLEND), 1, yuvBlendFile);
fclose(yuvBlendFile);
fclose(yuv420pFile);
return 0;
}
参考资料：
