I have a MPEG-DASH URI like below
https://test.com/default/index.mpd?begin=20230222T120430
where i have begin parameter specifying from where to start the playback. This is a dynamic MPD.
I want to know is begin parameter a standard parameter of MPEG-DASH. If yes, then in which document this parameter is specified.
MPEG-DASH is specified in ISO23009-1 - currently available at https://www.iso.org/standard/83314.html - which is the document in which begin would be specified if it were part of the DASH specification.
Appendix C.4 lays out a couple of MPD anchors for use in starting the stream at a particular time, but begin is not one of them.
Note that many players will not implement these anchors even though they are in the specification.