使用音视频拼接（avconcat）报错，反复示例多次，还是报错。

使用http://api.qiniu.com/status/get/prefop?id=5507f3637823de4068999571查询结果，提示error。error信息如下：

...
"cmd": "avconcat%2F1%2Fformat%2Fmp4%2FYW5ndXJpYTIubXA0%2FYW5ndXJpYTMubXA0",
"code": 3,
"desc": "The fop is failed",
"error": "execute fop cmd failed: unsupported cmd "

...

var qiniu = require('qiniu');

qiniu.conf.ACCESS_KEY = 'NUg.........';
qiniu.conf.SECRET_KEY = 'o5S9........';

var bucketName = 'haleywangtest';

var encodedUrl0 = qiniu.util.urlsafeBase64Encode('anguria2.mp4');
var encodedUrl1 = qiniu.util.urlsafeBase64Encode('anguria3.mp4');

var avconcatStr = 'avconcat/mode/1/format/mp4/'+encodedUrl0+'/'+encodedUrl1;

qiniu.fop.pfop(bucketName, 'anguria1.mp4', encodeURIComponent(avconcatStr), null, function(err, ret) {
console.log("=====result");
console.log(err);

});