Audacity is a free, open source, audio editor, available here.

If you want to backup you Audacity project, you can manually do it with "Save Lossless Copy of Project..." with the name, say, X, which will create X.aup (project file), a folder X_data, and, in there, a file called "Audio Track.wav".

Some drawbacks:

• It is a manual operation.
• It is blocked during playback.
• Envelopes are applied to the "Audio Track.wav" data. So data is altered and no more a real lossless copy of the project. Actually this operation is something between a backup and an export of the project to a foreign format.

A solution: Zip-Ada.

The latest commit (rev. 796) adds to the Preselection method a specific configuration for detecting Audacity files, so they are compressed better than with default settings.

Funny detail: that configuration makes, in most cases, the compression better than the best available compression with 7-Zip (v.19.00, "ultra" mode, .7z archive).

The compressing process is also around twice as fast as 7-Zip in "ultra" mode. This is no magic, since the "LZ" part of the LZMA compression scheme spends less time finding matches, in the chosen configuration for Zip-Ada.

A backup script could look like this (here for Windows' cmd):

rem --------------------------
rem Nice date YYYY-MM-DD_HH.MM
rem --------------------------

set year=%date:~-4,4%

set month=%date:~-7,2%
if "%month:~0,1%" equ " " set month=0%month:~1,1%

set day=%date:~-10,2%
if "%day:~0,1%" equ " " set day=0%day:~1,1%

set hour=%time:~0,2%
if "%hour:~0,1%" equ " " set hour=0%hour:~1,1%

set min=%time:~3,2%

set nice_date=%year%-%month%-%day%_%hour%.%min%

rem --------------------------

set audacity_project=The Cure - A Forest

zipada -ep2 "%audacity_project%_%nice_date%" "%audacity_project%.aup" "%audacity_project%_data\e08\d08\*.au"