Audacity 4.0 crossed 740 points on Hacker News less than three hours after its September 3 submission. The rush landed on an awkward detail in the release notes: six groups of Audacity 3 features are missing, including MIDI tracks, the Macro Manager, the scripting pipe, and Play-at-Speed. For people who automate batch exports or keep MIDI beside recorded audio, this is a compatibility decision dressed as a major-version update.
The attention is understandable. Audacity 4 rebuilds the interface in Qt, changes how clips are selected and moved, lets recording start anywhere on the timeline, and introduces the .aup4 project format. It is the largest visible break from the 3.x editor, and its official changelog says most Audacity 3 workflows remain. The exceptions deserve as much attention as the new interface.
The project format creates a one-way branch
Audacity 4 opens an .aup3 project and converts it to .aup4 while leaving the original file unchanged. The converted project cannot be saved back to .aup3, according to the 4.0 changelog. Older .aup projects can also be imported, but there is no supported round trip from the new format to Audacity 3.
That design gives users a built-in fallback: the source .aup3 stays where it was. Work completed after conversion belongs to the new branch, however. The .aup4 file stores preview thumbnails plus new clip and appearance data that the older container did not carry. Testing 4.0 on a copy or a noncritical project is sensible when a team may need to return to 3.x, because the release notes promise preservation of the original, not backward saving of later edits.
Clip editing now behaves more like a modern timeline
A click on a clip header selects the clip, and Shift-click adds more clips to the selection. Moving, trimming, and time stretching can apply to the whole selection. Clips can also be grouped so that copies, moves, and duplicates stay together. Audacity's release description says clips may move between mono and stereo tracks, while dropping one over another replaces the overlapping section instead of blocking the move.
Splitting now has a dedicated interaction: hold or press S, then click the waveform or clip header. Paste can create a track when one is needed, adapt compatible channel layouts, and accept audio files from the operating system clipboard. Alignment guides, sample-boundary snapping, and per-project snap settings round out the editing changes listed in the official changelog. These are practical reductions in menu travel during a dense edit.
Some muscle memory will fail. Sync-Lock is gone, replaced by explicit delete, cut, and paste variants that either leave a gap or move later material to preserve timing. The old Select, Envelope, Draw, and Multi-tool modes have also been removed. Their functions appear by context: sample drawing becomes available at individual-sample zoom, and volume envelopes appear in Clip gain mode. Audacity's transition guide documents ripple-editing shortcuts and a Classic workspace for users who want a more familiar layout, though the underlying editing rules have changed.
Recording received equally concrete changes. Playback can seek without stopping, the playhead remains visible while navigating, and recording can begin at any timeline position. Track headers now carry live playback and recording meters. Official Windows builds include ASIO playback and recording, while Audio Setup can follow operating-system device changes and refresh its device list, according to the 4.0 release.
The missing automation is more than a menu item
In Audacity 3, macros run fixed command sequences, such as applying effects to a batch of files. The scripting pipe lets an external Python or Perl program select audio, apply effects, rearrange clips, and export the result. Audacity's scripting manual describes it as the path for calculations and decisions that go beyond a fixed macro. Version 4.0 ships without both the Macro Manager and that pipe, so an existing automated job has no stated migration path in this release.
The other omissions reach narrower but established uses. Note tracks can display, play, edit, and export imported MIDI data in Audacity 3, as its Note Tracks manual explains. Time Tracks vary playback speed and pitch across a project, while Play-at-Speed lets a listener slow or accelerate playback without changing the exported audio. All three are absent from 4.0. Transcription, music-reference, and tempo-warp workflows should be checked against those gaps before moving active projects.
Plugin coverage also narrows. Audacity 4 supports VST3 and Nyquist, LV2 on Linux, and Audio Units on macOS. VAMP analyzers and LADSPA hosting are on the missing-feature list. Windows on Arm has a further restriction: the Windows download page says its ARM64 build has no plugin support at all and requires an Arm version of FFmpeg. The x86-64 Windows build does not carry that blanket plugin warning.
The release note adds a less specific warning: some exporting and rendering features, analyzers, and effects are still missing. It does not name each affected item. That makes a quick test with the exact file formats and effects used in production more useful than assuming the named compatibility list is exhaustive. Audacity says it is working to restore the six listed feature groups in future releases, but the 4.0 notes give no schedule.
Qt changes the contributor path too
The Qt rewrite brings native high-DPI rendering, dockable and floating panels, saved Workspaces, light and dark themes, and a high-contrast option. The project remains GPLv3 and ships for Windows, macOS, and Linux, according to Audacity's version 4 page. Modern, Classic, and Music workspace presets let one installation hold different panel layouts without turning the old tool modes back on.
For contributors, the rewrite changes the build environment. Audacity's build instructions require Qt 6.10, CMake, a generator such as Ninja, and a platform compiler. They also say large parts of version 4 are based on MuseScore Studio and that the dependency list remains long because MuseScore dependencies have not yet been cleaned up. A source checkout needs its submodules, so cloning the repository without them is no longer the complete starting point described by the project.
Audacity 3 has not vanished from the official site. Version 3.7.9 arrived on September 1, two days before 4.0, with FFmpeg 9 support and fixes for several project-corruption and data-loss cases. Its installers remain in Audacity's older-version archive. That recent maintenance release gives automation and legacy-plugin users a current 3.x baseline while they evaluate the rewrite.
Who should move first
Editors who mainly record, cut, arrange, and process waveform clips get the clearest immediate benefit. Direct multi-clip selection, grouping, record-anywhere placement, live per-track meters, and movable panels all target repeated actions in manual editing. Downloads are available as Windows x86-64 and ARM64 installers, macOS builds for Apple Silicon and Intel, and Linux x86-64 and ARM64 AppImages on the official download page.
Anyone whose workflow depends on macros, external scripts, MIDI or Time Tracks, Play-at-Speed, VAMP, or LADSPA has a reason to wait or run a controlled trial. The unchanged .aup3 original reduces the risk of opening an old project, but any subsequent .aup4 work stays on the version 4 side of the boundary. Audacity's compatibility notes are unusually direct about that split.
The next useful signals will be named additions in future release notes: a replacement path for automation, dates for MIDI and playback tools, and a precise inventory of the missing exporters, analyzers, and effects. Until those appear, the 4.0 release record supports two conclusions at once. Audacity 4 improves direct timeline editing, and upgrading an established workflow still requires checking what 4.0 leaves out.