Quantum Audio Time Stretch (or simply Quantum) is a desktop application for Windows and Mac OS that does only one thing: time stretching audio files.
Quantum is designed to give a good trade-off between audio quality and processing speed.
The time-stretching capabilities, the supported audio formats, and the available settings are the same in all versions (KVR Marketplace, Mac App Store or Microsoft Store).
However there are a few differences, mostly related to installation, updates and security. Check the table below for details.
|Feature||KVR Marketplace||Application store (Microsoft Store or Mac App Store)|
|Installation||The application must be downloaded and installed manually. Then it must be activated using a license key sent by e-mail.||Installation is as simple as any other app from the application store.|
|Updates||Updates must checked for, downloaded, and installed manually.||Updates are performed automatically from the application store.|
Windows: a warning from SmartScreen might be issued during installation.
macOS: the application can access all your files.
Windows: no warning during installation.
macOS: the application is sandboxed: it can only access files from your Music folder, and files that you explicitely open.
|Compatibility||Unofficial versions are available for Linux, Windows 32-bit, Windows 7, and other platforms.||Only available for Windows 10 and 11 (Intel 64 bit), and macOS (Intel 64 bit or Apple Silicon).|
|License Transfer||The application can be transferred to another computer, another account and/or another operating system using the license key.||The application is attached to your Microsoft or Apple account and can hence by transferred to another computer with the same account. However it cannot be transferred to another account, or to another operating system.|
|Demo version||A demo version is available. You can download it here.||No demo version is available. While you can download a demo version here, it will behave like the KVR Marketplace version and not like the application store version. Furthermore you must uninstall it before you buy the application store version, or else you will have two versions (with the same name).|
|Price||Cheaper. Payment is handled by the KVR Marketplace.||More expensive. Payment is handled by Microsoft or Apple.|
Time stretched using Quantum with default settings:
|130% of length (slower)|
|200% of length (two times slower)|
|66% of length (50% faster)|
Time stretched using Quantum with default settings, optimal settings, and using our reference implementation Tachyon:
|Time Stretched||Default settings||Quality 5, Transient sensitivity 0.8||Tachyon|
|130% of length|
|200% of length|
|250% of length|
|Processing speed1||5 - 10 times faster than real-time||a bit slower than real-time||5 - 10 times slower than real-time|
This page is a comparison of several free and commercial time stretching algorithms (with audio samples). Quantum is one of the tested algorithms.
The demo version has the following limitations:
|Not officially supported - use at your own risks|
Linux 64-bit (amd64)
Read the Online Documentation.
Read the FAQ (Frequently Asked Questions) part of the online documentation.
 Peter Gabriel, "Sledgehammer", Secret World Live, Geffen Records, 1986
 Steven Everitt, "Moon Scent", Elementals, KPM Music Ltd, 2009