YUV是一种亮度信号Y和色度信号U、V是分离的色彩空间，它主要用于优化彩色视频信号的传输，使其向后相容老式黑白电视。其中“Y”表示明亮度（Luminance或Luma），也就是灰阶值；而“U”和“V”表示的则是色度（Chrominance或Chroma），作用是描述影像色彩及饱和度，用于指定像素的颜色。 YUV格式分为两种类型：Packed类型和Planar类型。 

1、Packed类型：是将YUV分量存在在同一个数组中，每个像素点的Y、U、V是连续交错存储的；

2、Planar类型：是将YUV分量分别存放到三个独立的数组中，且先连续存储所有像素点的Y，紧接着存储所有像素点的U，最后是所有像素点的V。

一、将NV21转Yuv420p

// YYYYYYYY VUVU  --> YYYYYYYY UVUV
// 将NV21转换为Yuv420sp
public static byte[] nv21ToYuv420sp(byte[] src, int width, int height) {int yLength = width * height;int uLength = yLength / 4;int vLength = yLength / 4;int frameSize = yLength + uLength + vLength;byte[] yuv420sp = new byte[frameSize];// Y分量System.arraycopy(src, 0, yuv420sp, 0, yLength);for (int i = 0; i < yLength/4; i++) {// U分量yuv420sp[yLength + 2 * i] = src[yLength + 2*i+1];// V分量yuv420sp[yLength + 2*i+1] = src[yLength + 2*i];}return yuv420sp;
}

二、将YUV420SemiPlanner转换为NV21

// YYYYYYYY UVUV(yuv420sp)--> YYYYYYYY VUVU(nv21)
// 将YUV420SemiPlanner转换为NV21
public static byte[] yuv420spToNV21(byte[] src, int width, int height) {int yLength = width * height;int uLength = yLength / 4;int vLength = yLength / 4;int frameSize = yLength + uLength + vLength;byte[] nv21 = new byte[frameSize];// Y分量System.arraycopy(src, 0, nv21, 0, yLength);for (int i = 0; i < yLength/4; i++) {// U分量nv21[yLength + 2*i +1] = src[yLength+2*i];// V分量nv21[yLength + 2*i] = src[yLength + 2*i + 1];}return nv21;
}

 三、将YUV420Planner（I420）转换为NV21

// YYYYYYYY UU VV --> YYYYYYYY VUVU
// 将YUV420Planner（I420）转换为NV21
public static byte[] yuv420pToNV21(byte[] src, int width, int height) {int yLength = width * height;int uLength = yLength / 4;int vLength = yLength / 4;int frameSize = yLength + uLength + vLength;byte[] nv21 = new byte[frameSize];System.arraycopy(src, 0, nv21, 0, yLength); // Y分量for (int i = 0; i < yLength / 4; i++) {// U分量nv21[yLength + 2*i + 1] = src[yLength + i];// V分量nv21[yLength + 2*i] = src[yLength + uLength + i];}return nv21;
}

四、将nv21转换为yuv420p(I420)

// YYYYYYYY VUVU ---> YYYYYYYY UU VV
// 
public static byte[] nv21ToYuv420p(byte[] src, int width, int height) {int yLength = width * height;int uLength = yLength / 4;int vLength = yLength / 4;int frameSize = yLength + uLength + vLength;byte[] yuv420p = new byte[frameSize];// Y分量System.arraycopy(src, 0, yuv420p, 0, yLength);for (int i = 0; i < yLength/4; i++) {// U分量yuv420p[yLength + i] = src[yLength + 2*i + 1];// V分量yuv420p[yLength + uLength + i] = src[yLength + 2*i];}return yuv420p;
}

 五、将YV12转换为NV21

// YYYYYYYY VV UU --> YYYYYYYY VUVU
// 将YV12转换为NV21
public static byte[] yv12ToNV21(byte[] src, int width, int height) {int yLength = width * height;int uLength = yLength / 4;int vLength = yLength / 4;int frameSize = yLength + uLength + vLength;byte[] nv21 = new byte[frameSize];System.arraycopy(src, 0, nv21, 0, yLength); // Y分量for (int i = 0; i < yLength / 4; i++) {// U分量nv21[yLength + 2*i + 1] = src[yLength + vLength + i];// V分量nv21[yLength + 2*i] = src[yLength + i];}return nv21;
}

五种数据互相转换。

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