What happened
Muse Group released Audacity 4.0 on September 3, reworking both the interface and the editing model of the free audio editor. The interface has been rebuilt on Qt with native high-DPI rendering, editing is now non-destructive and clip-based, clips can be grouped so they move, copy and paste together, and ripple editing has arrived. Projects use a new .aup4 format, and official Windows builds include ASIO playback and recording.
The release notes are unusually frank about what is not there yet. Time Tracks, Note/MIDI tracks, the Mixer, the Macro Manager and scripting pipe, VAMP and LADSPA plugin hosting and play-at-speed are all missing from 4.0, alongside some exporting, rendering and analysis features promised for later updates.
The interesting bit
A major version with fewer features than the one before it is a real decision. Rebuilding the foundation of a program that is more than 25 years old means shipping the new base first and filling the rooms afterwards, and a new project format makes upgrading a commitment rather than an experiment.
ASIO on Windows is the quieter headline. Low-latency driver support is ordinary in commercial audio software and was long absent from official Audacity builds; for anyone recording through an audio interface on a PC, it may matter more than the new look.