使用libjpeg-turbo yuv转换成jpeg

1. 首先安装libjpeg-turbo库，可以通过以下命令进行安装：

   sudo apt-get install libjpeg-turbo8-dev

2. 在程序中添加以下头文件：

   #include <jpeglib.h>

3. 定义一个结构体变量来存储压缩后的JPEG数据：

   struct jpeg_compress_struct cinfo;
   struct jpeg_error_mgr jerr;

4. 初始化JPEG压缩对象：

   cinfo.err = jpeg_std_error(&jerr);
   jpeg_create_compress(&cinfo);

5. 设置JPEG压缩参数：

   cinfo.image_width = width;
   cinfo.image_height = height;
   cinfo.input_components = 3;
   cinfo.in_color_space = JCS_YCbCr;
   jpeg_set_defaults(&cinfo);
   jpeg_set_quality(&cinfo, quality, TRUE);

其中，width和height分别为图像的宽度和高度，quality为压缩质量，取值范围为0-100，0为最差质量，100为最好质量。

6. 设置输出文件：

   FILE *outfile = fopen(output_file, "wb");
   jpeg_stdio_dest(&cinfo, outfile);

7. 开始压缩：

   jpeg_start_compress(&cinfo, TRUE);
   JSAMPROW row_pointer[1];
   int row_stride;
   row_stride = width * 3;
   unsigned char *yuv_data = (unsigned char *)malloc(width * height * 3);
   // 将YUV数据转换成JPEG数据
   for (int i = 0; i < height; i++) {
       row_pointer[0] = &yuv_data[i * width * 3];
       jpeg_write_scanlines(&cinfo, row_pointer, 1);
   }

其中，row_stride为每行数据的字节数，yuv_data为存储YUV数据的数组。

8. 压缩结束，释放内存：

   jpeg_finish_compress(&cinfo);
   fclose(outfile);
   jpeg_destroy_compress(&cinfo);
   free(yuv_data);

完整代码示例：

#include <stdio.h>
#include <stdlib.h>
#include <jpeglib.h>

void yuv_to_jpeg(unsigned char *yuv_data, int width, int height, int quality, const char *output_file)
{
    struct jpeg_compress_struct cinfo;
    struct jpeg_error_mgr jerr;

    cinfo.err = jpeg_std_error(&jerr);
    jpeg_create_compress(&cinfo);

    FILE *outfile = fopen(output_file, "wb");
    jpeg_stdio_dest(&cinfo, outfile);

    cinfo.image_width = width;
    cinfo.image_height = height;
    cinfo.input_components = 3;
    cinfo.in_color_space = JCS_YCbCr;
    jpeg_set_defaults(&cinfo);
    jpeg_set_quality(&cinfo, quality, TRUE);

    jpeg_start_compress(&cinfo, TRUE);
    JSAMPROW row_pointer[1];
    int row_stride;
    row_stride = width * 3;
    for (int i = 0; i < height; i++) {
        row_pointer[0] = &yuv_data[i * width * 3];
        jpeg_write_scanlines(&cinfo, row_pointer, 1);
    }

    jpeg_finish_compress(&cinfo);
    fclose(outfile);
    jpeg_destroy_compress(&cinfo);
    free(yuv_data);
}

int main()
{
    // 读取YUV数据
    int width = 1920;
    int height = 1080;
    unsigned char *yuv_data = (unsigned char *)malloc(width * height * 3);
    FILE *fp = fopen("input.yuv", "rb");
    fread(yuv_data, 1, width * height * 3, fp);
    fclose(fp);

    // 转换成JPEG
    yuv_to_jpeg(yuv_data, width, height, 80, "output.jpg");

    return 0;
}