Collecting Mountain Ash Berries?

Looking around my yard, I notice that our Mountain Ash trees are loaded with berries. This is the ornamental version, which birds have spread all through my bush.

We normally leave these for our birds. Young robins and Bohemian waxwings love them. We also have ruffed grouse who will go way up into the tree and find precarious perches to get the berries (and we get to watch from our bedroom window).

Still, I'm musing about local food sources in our accidental, feral food forest.

The internet suggests mountain ash berries are somewhat edible but very tart (like chokecherries). Freezing or cooking is required to deactivate harmful compounds.

Anybody tried collecting and using these?