Hi3516DV500抓取摄像头数据异常

存储文件代码

void save_file_test(hi_video_frame_info *frame_data)
{
 FILE *pfd = fopen("stream_chn.yuv", "a+");
 hi_u8 *virt_addr;
 hi_u8 *virt_addr2;
 hi_u32 fpn_height, fpn_width;
 hi_s32 i;
 hi_s32 size;
 hi_u64 phy_addr;

 fpn_height = frame_data->video_frame.height;
 fpn_width = frame_data->video_frame.width;
 size = frame_data->video_frame.stride[0]*fpn_height*3/2;
 phy_addr = frame_data->video_frame.phys_addr[0];

 virt_addr = (hi_u8*)hi_mpi_sys_mmap(phy_addr, size);

 (hi_void)fwrite(virt_addr, size, 1, pfd);

 hi_mpi_sys_munmap(virt_addr, size);
 (hi_void)fflush(pfd);
 fclose(pfd);
}

2.调用代码

sample_capture_send_frame_to_capture_pipe函数
568行：
     /* discare first frame */
     if (i == 0) {
         if (hi_mpi_vi_get_chn_frame(capture_pipe, 0, &yuv_frame, milli_sec) == HI_SUCCESS) {
             hi_mpi_vi_release_chn_frame(capture_pipe, 0, &yuv_frame);
         }
     } else {
         if (hi_mpi_vi_get_chn_frame(capture_pipe, 0, &yuv_frame, milli_sec) == HI_SUCCESS) {
             const hi_vpss_grp vpss_grp = 1;
             save_file_test(&yuv_frame);
             break;
             //hi_mpi_vpss_send_frame(vpss_grp, &yuv_frame, milli_sec);
             hi_mpi_vi_release_chn_frame(capture_pipe, 0, &yuv_frame);

         }
     }

3.问题
上述函数调用后，发现数据写入到文件中，无法分析出写入数据是什么数据？