Is there a way to detect whether an MP4 is still playing to the land?

Is there a way to determine whether an MP4, MPEG or AVI which has been set to play with llParcelMediaCommandList has completed playing (assuming you did not know its duration in the first instance)? While I could figure out some ways to do it with an external webpage, I would much prefer to be able to make this work using LSL and LSL only. In the alternative, is there a preexisting webpage which can be called by llHTTPRequest() to return in less than 2048 characters the duration of a designated MP4, MPEG or AVI?

Thanks to all in the scripting community for your anticipated help!

Mu. A static media file starts playing at different times on each viewer, so it is never truly, "done playing." That's quite different from a live stream, of course.

The only way I've ever found to do this is to know the length of the file. And, due to lag and a number of other factors, that number is never "spot on". So, I'd have to say no to being able to do it with LSL only.

Does anybody know of a simple PHP script or, preferably, a preexisting URL where a call to same will reveal the playing length of an MP4?