Tachyon Audio
Time Stretch

Tachyon Audio Time Stretch is a desktop application for Windows and Mac OS that does only one thing: time stretching audio files.

Tachyon Audio Time Stretch is designed to achieve the best possible quality at any price.

What is Time Stretching?

Time stretching consists in changing the speed of a sound or music, without affecting the frequency and pitch.

Original file [1]

Time-stretched using Tachyon Audio Time Stretch:
30% faster

30% slower

Note: Playing any audio excerpt will stop the previous one if not finished.

Tachyon Audio Time Stretch is designed for the highest possible quality. A fast CPU is required, and only off-line processing is possible.

Features

Time stretch any music, track, speech or sound by any amount between 4 times slower and 4 times faster.
Professional-grade audio quality, based on state-of-the-art algorithms.
Support mono, stereo and multi-channel (5.1, 7.1) audio files. Fully preserve the stereo / spatial field.
Load and save WAVE (*.wav), AIFF/AIFC (*.aiff, *.aifc) and AU Sun/NeXT (*.au) audio files, in PCM 16 bit / 24 bit integer, or in 32 bit IEEE floating point format. Also load FLAC, OGG, MP3, M4A (AAC and ALAC) and OPUS files.
Support sampling rates from 8 kHz to 384 kHz.
The time stretching factor can be specified in many ways: length change, speed change, length from/to, tempo from/to, video FPS from/to, etc.
Accurate to a single sample (with sub-sample accuracy internally).
Transform multiple audio files simultaneously on multi-core computers.
Four quality settings (default 4 - highest quality) are available. Real-time processing speed on most computers with quality setting 1 (lowest)
Integrated mini player to preview the result before it is fully transformed.

Buy Tachyon Audio Time Stretch

Download the demo version

Version 2.1.0:

Windows (64-bit)

Mac OS

Limitations of the demo version

The demo version has the following limitations:

Only the first 30 seconds of audio are transformed.
The demo version should not be used for commercial activities.
The demo version will ask you to enter a license key every time you start it, so you need to click on the "Use the Demo Version" button.

Apart from that it is equivalent to the full version.

Download an unofficial version

The following unofficial versions of Tachyon are available for other operating systems.
They have not been extensively tested, and no support is provided for them. Use them at your own risks.
Check the installation instructions and known issues.
They run in demo mode. They can be unlocked to run in full mode using a license key from the Windows 64-bit or Mac OS version.

Not officially supported - use at your own risks
Linux (generic)	Windows (32-bit)	Generic (Java)

System requirements

Operating system:
- Windows: Windows 11 or later, Windows 10, Windows 8, Windows 7 (SP 1).
- Mac OS: Mac OS X 10.11 "El Capitan" or later (64 bit Intel), or MacOS 11 "Big Sur" or later (Apple M1).
Memory:
- Minimum: ~600 MB available for Tachyon, meaning a 1 GB system. This allows transforming one stereo, 384 kHz audio file at a time, or one 5.1, 96 kHz audio file at a time, both at the maximum quality.
- Recommended: at least 4 GB.
CPU speed: Any, but at least 2 GHz is recommended.
CPU cores: The more cores available, the more files Tachyon can process at the same time. Note however that multiple cores will not make the transformation of a single file faster.
Disk: Disk speed is generally not important. Disk capacity must be sufficient to store the original, transformed and temporary (being processed) files.

Listen to audio examples

A natural sound...

In each column below, one sample is the original one, and the others are time stretched using Tachyon Audio Time Stretch. Can you tell which one is the original one in each column?

Sample 1 [2]	Sample 2 [3]	Sample 3 [4]




Note: Playing any audio excerpt will stop the previous one if not finished.

A lot of efforts have been put to mitigate the traditional artifacts of audio time stretching: hashed or granular sound, boxy / metallic timbre, warbling, smearing, "thin" sounding, etc.

Tachyon Audio Time Stretch is designed to always sound natural, never "processed".

Optimised for quality...

Time stretching is a difficult DSP problem. Any time stretching algorithm is a compromise between processing speed and quality.

The following table compares two music excerpts time stretched using:

Tachyon Audio Time Stretch (at maximum and minimum quality)
A common time-domain technique (WSOLA)
A common frequency-domain technique (Phase Vocoder)

	Drums [5]	Pop / Voice [6]	Note: Playing any audio excerpt will stop the previous one if not finished.
Original
Time-stretched at 160% of the length by:			Processing speed Approximate, on a 3 GHz processor	Notes
WSOLA			> 100x (> 100 times faster than real-time)	Based on SoundTouch.
Phase Vocoder			> 10x	Based on Gradient time stretch.
Tachyon			< 0.1x	At maximum (and default) quality 4
Tachyon			~ 3x	At minimum quality 1

As you can see, Tachyon Audio Time Stretch is optimised for the best possible quality, not for processing speed.

If you want to time stretch a single instrument by +/- 20%, you need a time stretching algorithm.
If you want to time stretch your favorite playlist at half the speed and enjoy the result, you need Tachyon Audio Time Stretch.

High fidelity...

High fidelity means "close to the original".

Each of the following samples alternates between an untransformed music and the same music transformed with Tachyon Audio Time Stretch.

Sample 1 (New Age [7])	Sample 2 (Pop / Rock [8])	Sample 3 (Classical [9])

Notes
The musics have first been transformed using Tachyon using a fixed ratio, and then a DAW has been used to slice and join pieces from both the original and the transformed versions. Tachyon itself does not support changing the time stretching ratio in the middle of a song.

Samples 1 and 3 alternate between original and half speed. Sample 2 alternates between original and 1.6 times slower.

And more...

This page contains other audio examples time stretched by Tachyon and by 3 other time stretching algorithms.

This YouTube channel contains entire musics time stretched at half tempo (50% of speed / 200% of length) by Tachyon:

Chandelier by Sia - Pop
Ethnicolor 1 by Jean-Michel Jarre - Electronic / New Age
The Imperial March by John Williams (from Star Wars) - Classical
Cartoon Heroes by Aqua - Pop

Due to YouTube re-encoding the audio, quality might be slightly lower than what Tachyon Audio Time Stretch actually produces, especially in under 720p resolutions.

Screenshots

Click on an image to zoom it in and out.