The URL of the fête set in jazz’s ur-city—the New Orleans Jazz and Heritage Festival—has proved, this year, sadly prophetic: nojazzfest.com. But while most music festivals worldwide have fallen to the pandemic, a few are bravely soldiering on, online. Among them is this canny charivari, in which such eminences as Mary Halvorson, Maya Beaser, George Lewis, Miya Masaoka, Meredith Monk, Vijay Iyer, and Moor Mother offer six straight hours of jazzy New Music and cerebral jazz. —E.E.