PSDK相机管理，下载媒体文件，下载完之后是否需要释放结构体参数，示例中没有释放？

1、DjiCameraManager_DownloadFileList(position, &s_meidaFileList) 下载完之后是否需要释放s_meidaFileList结构体参数，源码中没看到释放？

2、DjiCameraManager_DownloadFileList() 和DjiCameraManager_DownloadFileByIndex()的区别

DjiCameraManager_DownloadFileList：是下载选定的相机媒体文件列表，那么是下载文件还是仅获取文件列表信息？

DjiCameraManager_DownloadFileByIndex：是通过文件索引下载选定的相机媒体文件；

那么DjiCameraManager_RegDownloadFileDataCallback注册的回调函数是在DjiCameraManager_DownloadFileList和DjiCameraManager_DownloadFileByIndex哪个函数之后执行？

3、下载完之后，如果不删除图片，再次下载文件，是否会导致重复下载？

源码示例粘贴如下：

static T_DjiReturnCode DjiTest_CameraManagerMediaDownloadAndDeleteMediaFile(E_DjiMountPosition position)
{
    T_DjiReturnCode returnCode;
    T_DjiOsalHandler *osalHandler = DjiPlatform_GetOsalHandler();
    uint16_t downloadCount = 0;
    uint16_t subFileDownloadCount = 0;
    int i = 0, j= 0;

    s_nextDownloadFileIndex = 0;
    returnCode = DjiCameraManager_RegDownloadFileDataCallback(position, DjiTest_CameraManagerDownloadFileDataCallback);
    if (returnCode != DJI_ERROR_SYSTEM_MODULE_CODE_SUCCESS) {
        USER_LOG_ERROR("Register download file data callback failed, error code: 0x%08X.", returnCode);
        return returnCode;
    }
    returnCode = DjiCameraManager_ObtainDownloaderRights(position);
    if (returnCode != DJI_ERROR_SYSTEM_MODULE_CODE_SUCCESS) {
        USER_LOG_ERROR("Obtain downloader rights failed, error code: 0x%08X.", returnCode);
    }

    returnCode = DjiCameraManager_DownloadFileList(position, &s_meidaFileList);
    if (returnCode != DJI_ERROR_SYSTEM_MODULE_CODE_SUCCESS) {
        USER_LOG_ERROR("Download file list failed, error code: 0x%08X.", returnCode);
        return returnCode;
    }

    if (s_meidaFileList.totalCount > 0) {
        downloadCount = s_meidaFileList.totalCount;
        subFileDownloadCount = s_meidaFileList.fileListInfo->subFileListTotalNum;
        printf(
            "\033[1;33;40m -> Download file list finished, total media file count is %d "
                   "the following %d is list details: \033[0m\r\n",
            s_meidaFileList.totalCount, downloadCount);

...
        osalHandler->TaskSleepMs(1000);
       downloadCount =  s_meidaFileList.totalCount;
        for (i = 0; i < downloadCount; ++i) {
            redownload:
            if (i != s_nextDownloadFileIndex) {
                i = s_nextDownloadFileIndex;
            }
            returnCode = DjiCameraManager_DownloadFileByIndex(position, s_meidaFileList.fileListInfo[i].fileIndex);
            if (returnCode != DJI_ERROR_SYSTEM_MODULE_CODE_SUCCESS) {
                USER_LOG_ERROR("Download media file by index failed, error code: 0x%08X.", returnCode);
                s_nextDownloadFileIndex--;
                goto redownload;
            }

            if (s_meidaFileList.fileListInfo[i].type == DJI_CAMERA_FILE_TYPE_LDRT) {
                for (j = 0; j < s_meidaFileList.fileListInfo[i].subFileListTotalNum; j++) {
                    subFileRedownload:
                    returnCode = DjiCameraManager_DownloadSubFileByIndexAndSubType(position,
                                                                                s_meidaFileList.fileListInfo[i].fileIndex,
                                                                                s_meidaFileList.fileListInfo[i].subFileListInfo[j].type);
                    if (returnCode != DJI_ERROR_SYSTEM_MODULE_CODE_SUCCESS) {
                        USER_LOG_ERROR("Download sub media file by index and type failed, error code: 0x%08X.", returnCode);
                        goto subFileRedownload;
                    }
                }
            }
        }

        if (s_meidaFileList.fileListInfo[0].type == DJI_CAMERA_FILE_TYPE_JPEG) {
            returnCode = DjiCameraManager_DeleteFileByIndex(position, s_meidaFileList.fileListInfo[0].fileIndex);
            if (returnCode != DJI_ERROR_SYSTEM_MODULE_CODE_SUCCESS) {
                USER_LOG_ERROR("Delete media file by index failed, error code: 0x%08X.", returnCode);
                return returnCode;
            }
        }
        osalHandler->TaskSleepMs(1000);
    } else {
        USER_LOG_WARN("Media file is not existed in sdcard.\r\n");
    }

    returnCode = DjiCameraManager_ReleaseDownloaderRights(position);
    if (returnCode != DJI_ERROR_SYSTEM_MODULE_CODE_SUCCESS) {
        USER_LOG_ERROR("Release downloader rights failed, error code: 0x%08X.", returnCode);
    }
    return DJI_ERROR_SYSTEM_MODULE_CODE_SUCCESS;
}