PHP Ffmpeg Gif Resize exec无效

Question

输出文件＆gt; '..'未被识别为内部或外部命令， 可操作程序或批处理文件。

我的代码：

private function createFfmpegGif($ORIGINAL_GIF_NAME,$THUMBNAIL_GIF_NAME,$SMALL_THUMBNAIL_GIF_NAME,$SMALL_GIF_NAME){
    $cmd = '../libs/ffmpeg/bin/ffmpeg.exe -i '.$ORIGINAL_GIF_NAME.'-vf scale=160:90 '.$THUMBNAIL_GIF_NAME.'  2> ../../uploads/posts/out.txt';
    exec($cmd);
}