Slow Down FFS is an audio manipulation program for Windows and Mac OS X which allows you to modify the tempo of a recording (from 25-200%) and/or adjust the pitch, with quarter-tone precision, up to one octave above or below the original. The interface is designed to easily start, pause and resume anywhere in the track or mark a particular selection for looped playback. The adjusted audio can also be exported for use with another playback device (e.g. your phone, iPod etc.) or a different audio application.
The two processing options included with Slow Down FFS are Phase Vocoder (using Rubber Band technology) and SOLA (using SoundTouch). In general, the PV method is slower but produces superior audio (particularly with slowed down tracks), so depending on the music and your particular needs - and patience level - you may find it useful to alternate between the two.
Slow Down FFS currently supports the following file formats for both input and output:
- Microsoft Wave (.wav)
- MPEG-2 Audio Layer III (.mp3)
- Audio Interchange File Format (.aiff)
Also, video files in MPEG-4 Part 14 (.mp4) format can be used as input.
Slow Down FFS is completely free and open source, licensed under the GNU Public License. Slow Down FFS is also 100% adware/junkware free and does not require running an installation: just extract the contents wherever you like and run it (for the Mac version, I recommend dragging the .app file into your Applications folder).
For source code, please see the links below.
Download Slow Down FFS (version 1.0.2):
 | Windows (64-bit) | Download |
 | Mac OS X (Snow Leopard or higher) | Download |
Please note that the Windows version requires MS VC2013 64-bit runtime. If you see an error regarding MSVCP120.dll, you will need to download and install the runtime package (vcredist_x64.exe) from here.
Additionally, the phase vocoder component in Windows requires the MS VC 2010 32-bit runtime. If you see an error regarding MSVCR100.dll (or something similar), you will need to download and install it (vcredist_x86.exe) from here.
For information regarding running third party applications in OS X, please read this.
Source Code:
Version 1.0.2 Updates
- - Multiple instances of the program are now supported.
- - Added delete and crop operations to reduce the current file size as desired (this will improve performance).
- - Added copy/cut/paste operations (this also works from one instance of the program to another).
- - Added undo/redo stack.
- - Improved selection and navigation controls - arrow keys (+ shift for selection end) can be used for finer control over selection and caret position.
Version 1.0.1 Updates
- - Text boxes are now editable.
- - Added .mp4 (video) support.
- - Files with special Unicode characters in the name can now be loaded.
- - Fixed issue with playback controls not working correctly for the current file after a File Open has failed.
- - Fixed occasional playback stuttering issue after adjusting tempo or pitch.
- - Releasing the slider in the same place as it already was no longer causes re-processing.