下载MP4文件，并且重命名， PHP的内存需要设置大点

/**
     * 下载MP4文件，并且重命名
     */
    public function downloadmp4()
    {

        $ids = input('get.ids/d');
        $data = $this->model->where(['id' => $ids])->find();
        if (!$data) {
            $this->error('数据不对');
        }
        $file_url = $data->file_old_url;

        $out_filename = $data->filename;

        $file = @fopen($file_url, "r");

        if($file){
            $content="";

            while(!feof($file)){//测试文件指针是否到了文件结束的位置

                $data=fread($file,1024);

                $content.=$data;

            }

            fclose($file);

            $filesize = strlen($content);

            header('Accept-Ranges: bytes');

            header('Accept-Length: ' . $filesize);

            header('Content-Transfer-Encoding: binary');

            header('Content-type: application/octet-stream');

            header('Content-Disposition: attachment; filename=' . $out_filename);

            header('Content-Type: application/octet-stream; name=' . $out_filename);

            echo $content;

            die();

        }else{
            echo "文件不存在";

        }

    }