用streamlink录制应该怎么修改录制的文件格式？

录制的bigo直播，自定义OutTmpl文件名正确但是后缀还是mp4，我应该怎么做？谢谢
```[[Shows]]
ID = '123'
Enable = true
Platform = 'streamlink'
RoomID = 'https://www.bigo.tv/123'
StreamerName = '123'
OutTmpl = "{{ .StreamerName }} {{ now | date \"20060102 150405\"}}.ts"
```