免費又開源的 Audacity，剪聲音、去雜訊、轉檔夠用嗎

What's new in this version:

IMPROVEMENTS

Effects:
- LADSPA, VST and Audio Unit (OS X) effects now support real-time preview, save/load of user presets and saving effect settings across sessions. Note: Real-time preview does not yet support latency compensation.
- VST effects now support import/export of FXB preset banks.
- Shell VST effects that host multiple plugins are now supported.
- All Effect Menu items (built-in or plugin) can now be used in a Chain.
- Items in the Effect, Generate or Analyze Menus can be sorted or grouped by name, publisher or class of effect.
- Noise Removal is improved and renamed to "Noise Reduction".
- Change Speed has new time controls for current and new length. You can now enter the speed change as a multiplier e.g. "2" is twice as fast.
- New "Crossfade Tracks" effect can be used for crossfading two tracks. This replaces Cross Fade In and Cross Fade Out.
- Nyquist Prompt and most shipped Nyquist effects now have Preview button.

Interface:
- Redesigned Meter Toolbars: The default shows separate Record and Playback Meters, half-height so they can be wider while docked, in gradient style.
- A frequency selection can now be made (and spectral edit effects applied to those frequencies) when in a spectrogram view. You can also create or adjust frequency selections in a new "Spectral Selection Toolbar" (available at View > Toolbars).
- Transcription Toolbar (Play-at-speed) can now loop play and cut-preview.
- Timer Record now saves recordings automatically into an existing project.
- New Armenian translation.

Operating system and sound device support:
- (Windows) Audacity 2.1.0 requires Windows XP SP3 (32-bit) or XP SP2 (64-bit), Vista, Windows 7, Windows 8 or 8.1.(Windows) Audacity is now compiled using Visual Studio 2013.
- (Windows) Recording with WASAPI host now includes experimental support for physical inputs (up to 24-bit depth) as well as loopback recording.
- (OS X) 10.10 (Yosemite) is now supported including Apple Audio Units.
- (Linux Ubuntu) Under Unity, keyboard shortcuts are not visible in the Audacity menus. Keyboard shortcuts are visible if you install the classic GNOME Flashback interface or under Unity if you open Audacity with the UBUNTU_MENUPROXY=0 environment variable. Audacity compiled from source will ship with src/audacity.desktop.in set to UBUNTU_MENUPROXY=0 but it will remain up to distributions to use this desktop file.

BUG FIXES

Interface:
- Typing "j" or "k" in a label track activated the "move cursor" shortcut.Spectrogram log (f) view displayed incorrectly until vertically zoomed.
- Fixed crash after zooming out on vertical scale beyond +/-1.0.
- Selections made with Selection Toolbar were not restored after Undo.
- Undo could fail silently if a selection included/touched a clip boundary.

Imports and Exports:
- If there were invalid FFmpeg libs in system PATH this prevented Audacity recognising the installed FFmpeg or the FFmpeg specified in audacity.cfg.

Mac OS X:
- Fix uninitialized buffer - this should correct playback buzz or crackle where the upper of multiple tracks started with or contained white space.
- Device names were corrupted when using system language other than English.
- Fixed crashes using (external program).
- Waves v9 Audio Units should now work correctly.

GNU/Linux:
-  Fix "Audacity already running" error when using the command-line or context menu to open multiple or further files.
- Fix segfault exporting an FFmpeg format to an unwritable folder.
- Fix silent failure exporting FFmpeg, MP2 or OGG to an unwritable folder.
- Fix ENTER activated an effect when OK button was greyed out.