java音视频拼接报unsupported cmd，帮看下哪里错了？

Question

        
        Auth auth = Auth.create(ACCESS_KEY,SECRET_KEY);
        OperationManager manager = new OperationManager(auth);
        //音频拼接
        String encodedUrl1 = UrlSafeBase64.encodeToString("dushen01.mp4");
        String encodedUrl2 = UrlSafeBase64.encodeToString("dushen02.mp4");
        String fops = "avconcat/2/format/mp4/"+encodedUrl1+"/"+encodedUrl2;
        fops += "|saveas/"+UrlSafeBase64.encodeToString("audio:dushen0.mp4");
        fops = URLEncoder.encode(fops, "utf-8");
        String persistentId = manager.pfop("audio", "dushen03.mp4", fops,null);

报错信息为：
{

"code": 3,
"desc": "The fop is failed",
"id": "z0.56444dc67823de48a8034865",
"inputBucket": "audio",
"inputKey": "dushen03.mp4",
"items": [
    {
        "cmd": "avconcat%2F2%2Fformat%2Fmp4%2FZHVzaGVuMDEubXA0%2FZHVzaGVuMDIubXA0%7Csaveas%2FYXVkaW86ZHVzaGVuMC5tcDQ%3D",
        "code": 3,
        "desc": "The fop is failed",
        "error": "execute fop cmd failed: unsupported cmd ",
        "returnOld": 0
    }
],
"pipeline": "0.default",
"reqid": "VH4AAK1otF4V5xUU"

}，各位大神帮看下原因，定位了两天都想不出哪里错了，谢谢