Need a working progress display

Have coded an application that is working fine and stabile with big files up to 2 GB.
This complex process could be last up to 20 Minutes.

All trying to manage a kind of progress feedback, like animated Gifs or JavaScript Animations or Alerts or blinking text messages failed.
When the working process starts all kind of screen animation freezed.
Then the ordinary user has to wait and hope …no feedback up to 20 Minutes.

So, is there a way to get a working progress-display, a progress bar or something else during the progress?

Any idea?

In ExeOutput 2, the UI process is separated from the PHP process so it will be possible to implement a progress bar for instance.