This page is a preview of 4 new audio time stretching algorithms currently in development.
The algorithms have the code-names "Quantum", "Tachyon", "Schrödinger" and "Heisenberg".
Audio examples
Performance comparison
SoftwareNews!
Scientific References
Musical References
History
A few audio examples are much better than a lot of words...
Notes:
Original |
Electronic [1]
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Time stretching ratio | Quantum | Tachyon | Schrödinger | Heisenberg |
0.5 | ||||
0.9 | ||||
1.3 | ||||
2.0 | ||||
4.0 | ||||
Cycle 2.0, 0.6, 1.5, 5/9 |
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0.2 | ||||
20 | ||||
Original |
Pop [2]
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Time stretching ratio | Quantum | Tachyon | Schrödinger | Heisenberg |
0.5 | ||||
0.9 | ||||
1.3 | ||||
2.0 | ||||
4.0 | ||||
Cycle 2.0, 0.6, 1.5, 5/9 |
||||
0.2 | ||||
20 | ||||
Original |
Guitar [3]
|
|||
Time stretching ratio | Quantum | Tachyon | Schrödinger | Heisenberg |
0.5 | ||||
0.9 | ||||
1.3 | ||||
2.0 | ||||
4.0 | ||||
Cycle 2.0, 0.6, 1.5, 5/9 |
||||
0.2 | ||||
20 | ||||
Original |
New Age [4]
|
|||
Time stretching ratio | Quantum | Tachyon | Schrödinger | Heisenberg |
0.5 | ||||
0.9 | ||||
1.3 | ||||
2.0 | ||||
4.0 | ||||
Cycle 2.0, 0.6, 1.5, 5/9 |
||||
0.2 | ||||
20 | ||||
High quality comes with a price, usually slow processing speed. The following table shows an approximation, for each algorithm, of the time required to produce one minute of time stretched audio (stereo, 44.1 kHz) on a 3 GHz processor. It also shows the relative quality (subjective, your opinion might differ), the minimum and maximum supported time stretching ratios, and the main goals:
Time to produce 1 min | Quality (Subjective) |
Transformation ratios
Max / Recommanded |
Main Goals | |||
---|---|---|---|---|---|---|
Quantum | 6 - 8 seconds | 😐 | Medium | 😐 | 0.25 - 4 / 0.7 - 1.3 | Best speed/quality trade-off, simplicity |
Tachyon | 10 - 15 minutes | 😱 | Highest | 😃 | 0.25 - 4 / 0.5 - 2 | Highest quality at any price |
Schrödinger | < 2 seconds | 😃 | Lowest | 😒 | 0.25 - 4 / 0.8 - 1.2 | Fastest speed, for solo, open source |
Heisenberg | ~ 30 seconds | 😒 | Medium | 😐 | 0.01 - 1000 / 0.1 - 100 | Huge transformation ratios, pleasant sound |
New! The Tachyon algorithm is available for sale as a commerical, desktop application: Tachyon Audio Time Stretch.
the Quantum algorithm is available as a command-line, beta version.
Download TimeStretchQuantum.7z, a beta-version of the Quantum audio time stretching algorithm, as a command-line tool.
Usage
java -jar TimeStretchQuantum.jar <input file> <time-stretch ratio> <output-file>
Limitations
The science behind these algorithms...
[1] Zdeněk Průša and Nicki Holighaus, "Phase Vocoder Done Right", 25th European Signal Processing Conference, EUSIPCO, 2017 (1), (2)
[2] N. Juillerat, "Audio Time Stretching with Controllable Phase Coherence", 142nd Audio Engineering Society Convention, AES 142, 2017 (2)
[3] N. Juillerat, B. Hirsbrunner, "Audio Time Stretching with an Adaptive Multiresolution Phase Vocoder", IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP 2017 (2), (4)
[4] Derry FitzGerald, "Harmonic/Percussive Separation using Median Filtering", proc. of the 13th intl. conf on Digital Audio Effects, 2010 (3)
[5] N. Juillerat, S. Schubiger-Banz, S. M. Arisona, "Enhancing the Quality of Audio Transformations Using the Multi-Scale Short-Time Fourier Transform", IASTED International Conference on Signal Processing, IASTED SIP 2008 (2), (4)
[6] Tan Roland K. C. and Lin Amerson H. J, "A Time-Scale Modification Algorithm Based on the Subband Time-Domain Technique for Broad-Band Signal Applications", Journal of the Audio Engineering Society, vol. 48, no. 5, pp. 437-449, 2000 (3)
[7] Jean Laroche and Mark Dolson, "Improved Phase Vocoder Time-Scale Modification of Audio", IEEE Transactions on Speech and Signal Processing, vol. 7, no. 3, May 1999 (4)
[8] Werner Verhelst, Marc Roelands, "An Overlap-Add Technique Based on Waveform Similarity (WSOLA) for High Quality Time-Scale Modification of Speech", IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP 1993 (3)
Notes:
[1] Jean-Michel Jarre, "Oxygène part. 4", Oxygène, Disques Dreyfus, 1977
[2] Peter Gabriel, "Sledgehammer", Secret World Live, Geffen Records, 1986
[3] (Unknown) Sample n° 4 (Guitare) from "Comparatif Time Stretching et Pitch Shifting", Audiofanzine, 2008
[4] Melanie G 'MySweetDarkness', "The Morn", Through the Shadow and the Light, Everlasting Dream, 2007