libyuv接口I420ToRGB24的实际使用

I420ToRGB24

1.接口定义:
int I420ToRGB24(const uint8* src_y, int src_stride_y,
const uint8* src_u, int src_stride_u,
const uint8* src_v, int src_stride_v,
uint8* dst_frame, int dst_stride_frame,
int width, int height);

2.实际使用
首先弄清楚两种图片格式的存储格式：

rgb24图像格式：
1个像素为3个字节，b\g\r三个通道分别1个字节

	const uint8 *nv12_y = (const uint8*)image->data;
    int nv12_y_stride = image->width;
    const uint8 *nv12_uv = nv12_y + nv12_y_stride * image->height;
    int nv12_uv_stride = nv12_y_stride;

	uint8 *i420_image = NULL;
	i420_image = (uint8*)malloc(image->width * image->height * 1.5);
    uint8* i420_image_y_ptr = i420_image;
    uint8* i420_image_u_ptr = i420_image_y_ptr + (image->width * image->height);
    uint8* i420_image_v_ptr = i420_image_u_ptr + (int)(image->width * image->height * 0.25);
	
	out_cv_mat.create(image->height, image->width, CV_8UC3);

    libyuv::I420ToRGB24(
         i420_image_y_ptr, image->width,
         i420_image_u_ptr, (image->width >> 1),
         i420_image_v_ptr, (image->width >> 1),
         out_cv_mat.data, (image->width * 3),//三通道，1个通道为1个字节
         image->width, image->height);