Regarding the "minimumUpdatePeriod" parameter in the live stream, what is the processing mechanism of dash.js?

[zxyyyyyy512]

1. At the beginning, we set the parameters in the live streaming manifest as follows:
   minimumUpdatePeriod = "PT2.000S"

Such parameter settings lead to a very slow playing start of the live stream, and it takes about 10 seconds to play the first frame of the video. We analyzed the reason for the slow playing start and found that the first fragment was downloaded after downloading 5 manifest files in a row, which caused the slow playing start of the live stream. 2. Then we modify the parameter "minimumUpdatePeriod" and fragment duration "d": minimumUpdatePeriod = "PT5.000S" In this case, I found that the start-up was very fast, it only took 2-3s. Also I observed that the first fragment downloaded immediately after downloading only one manifest file.

Could you tell me what is the reason for this behavior? What mechanism causes the first fragment to be downloaded after downloading 5 manifest files continuously in the first case? Thanks.

dash.js version: dash.js 4.6.0
manifest：