C语言公式法将yuv视频转换成rbg格式

以下是将YUV视频转换为RGB格式的C语言代码：

// 定义转换函数
void yuv2rgb(int y, int u, int v, unsigned char *r, unsigned char *g, unsigned char *b) {
    int r_, g_, b_;

    // 计算红色分量
    r_ = (int)(y + 1.370705 * (v - 128));
    if (r_ < 0) {
        r_ = 0;
    } else if (r_ > 255) {
        r_ = 255;
    }
    *r = (unsigned char)r_;

    // 计算绿色分量
    g_ = (int)(y - 0.698001 * (v - 128) - 0.337633 * (u - 128));
    if (g_ < 0) {
        g_ = 0;
    } else if (g_ > 255) {
        g_ = 255;
    }
    *g = (unsigned char)g_;

    // 计算蓝色分量
    b_ = (int)(y + 1.732446 * (u - 128));
    if (b_ < 0) {
        b_ = 0;
    } else if (b_ > 255) {
        b_ = 255;
    }
    *b = (unsigned char)b_;
}

// 将YUV格式的像素转换为RGB格式的像素
void yuv420p_to_rgb24(unsigned char *yuv420p, unsigned char *rgb24, int width, int height) {
    int y, u, v;
    unsigned char *y_ptr, *u_ptr, *v_ptr, *r_ptr, *g_ptr, *b_ptr;
    int y_stride, u_stride, v_stride, r_stride, g_stride, b_stride;
    int i, j;
    int rgb_index, y_index, u_index, v_index;

    // 计算每个分量的步幅
    y_stride = width;
    u_stride = width/2;
    v_stride = width/2;
    r_stride = width * 3;
    g_stride = width * 3 + 1;
    b_stride = width * 3 + 2;

    // 分别获取YUV和RGB的指针
    y_ptr = yuv420p;
    u_ptr = yuv420p + y_stride * height;
    v_ptr = u_ptr + u_stride * height / 2;
    r_ptr = rgb24;
    g_ptr = rgb24 + 1;
    b_ptr = rgb24 + 2;

    // 遍历图片的每个像素，并将YUV转换为RGB
    for (i = 0; i < height; i++) {
        for (j = 0; j < width; j++) {
            y_index = i * y_stride + j;
            u_index = (i/2) * u_stride + (j/2);
            v_index = (i/2) * v_stride + (j/2);

            y = y_ptr[y_index];
            u = u_ptr[u_index];
            v = v_ptr[v_index];

            rgb_index = i * r_stride + j * 3;

            yuv2rgb(y, u, v, r_ptr + rgb_index, g_ptr + rgb_index, b_ptr + rgb_index);
        }
    }
}

具体使用方法可以参考以下 snippet：

int main() {
    FILE *fp_in, *fp_out;
    unsigned char *yuv420p_buf, *rgb24_buf;
    int width = 1280, height = 720, i, j;
    int yuv420p_size = width * height * 3 / 2;
    int rgb24_size = width * height * 3;

    // 读取YUV视频数据
    fp_in = fopen("test.yuv", "rb");
    yuv420p_buf = (unsigned char *) malloc(yuv420p_size);
    fread(yuv420p_buf, 1, yuv420p_size, fp_in);
    fclose(fp_in);

    // 将YUV格式的视频数据转换为RGB格式的视频数据
    rgb24_buf = (unsigned char *) malloc(rgb24_size);
    yuv420p_to_rgb24(yuv420p_buf, rgb24_buf, width, height);

    // 将转换后的RGB视频数据写入文件
    fp_out = fopen("test.rgb", "wb");
    fwrite(rgb24_buf, 1, rgb24_size, fp_out);
    fclose(fp_out);

    return 0;
}