智能媒体服务这个转场无法生效，怎么解决？

是生效的，这里有2个问题，
1、TrackId在2个视频不是一致的，导致大家不是同一条轨道，比如2个视频的均设置为，"TrackId": 1,
2、没有给视频1设置ID，导致转场指向的From：1不生产「即预览器不知道哪个是ID为1的片段」。

终上，正确的参考是，

  "VideoTrackClips": [{
   "Type": "Video",
   "MediaURL": "https://hrjtest.oss-cn-shanghai.aliyuncs.com/official/you/resources/9759e6ca-07bd-47bd-ae62-8c40a34939c8.mp4",
   "TimelineIn": 0,
   "TimelineOut": 6.92,
   "AdaptMode": "Contain",
   "TrackId": 1,
      "Id":1,
   "In": 0,
   "Out": 6.92,
   "Effects": [{
    "Type": "Background",
    "SubType": "Blur",
    "Radius": 0.1
   }, {
    "Type": "Volume",
    "Gain": 0
   }]
  }, {
   "Type": "Video",
   "MediaURL": "https://hrjtest.oss-cn-shanghai.aliyuncs.com/official/you/resources/e6406704-6032-4c27-bf78-7251cf7d95b7.mp4",
   "TimelineIn": 6.92,
   "TimelineOut": 36.92,
   "AdaptMode": "Contain",
   "TrackId": 1,
      "Id":4,
   "In": 0,
   "Out": 30,
   "Effects": [{
    "Type": "Background",
    "SubType": "Blur",
    "Radius": 0.1
   }, {
    "Duration": 0.5,
    "From": 1,
    "Id": 2,
    "SubType": "directional",
    "Type": "Transition"
   }, {
    "Type": "Volume",
    "Gain": 0
   }]
  }]
 }],
 "AudioTracks": [{
  "AudioTrackClips": []
 }],
 "From": "openAPI",
 "FECanvas": {
  "Width": 1080,
  "Height": 1920
 }
}

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