Music Software

New Paulstretch OS X build

As software projects go, PaulStretch is rather a shadowy enigma. Since I did the initial Mac OS X port, I’ve had very, very sporadic communications with the author Nasca Octavian Paul about it.

Then there’s the issue of versioning. Paul started a github repository, but it hasn’t been updated since March. It’s currently at version 2.2.2, but the only difference between 2.2-2 and 2.2-1 is that the version number it reports has changed.

At any rate, today I did a new build which is 1) OS X 10.6 (forward compatible with Lion, but perhaps not backwards compatible to Leopard or Tiger) 2) Up to date build, incorporating all of Paul’s changes. I also spent some time playing with it to make sure it works properly.

You can download it here:

It also has the latest refinements of the build scripts used to build PaulStretch from source. I use CMake, which is Kitware’s cross-platform build tool. CMake keeps getting smarter, and my CMake recipe for PaulStretch will download all the prerequisite libraries, build them, and then download the PaulStretch source, build it, and generate an Apple App Bundle.

And CMake really is cross-platform — the same build recipe will work unmodified on Linux (which I have tested) and possibly on Windows (which I haven’t tried).

If you still have a PowerPC Mac, you can try using which a friend of mine built, but it isn’t the most recent version of PaulStretch.

128 replies on “New Paulstretch OS X build”

Thank you for porting this. I plan on destroying “Get Lucky” for my radio show.

Paulstretch is cool, but honestly, it kinda makes everything sound the same. I can tell when people use it in tracks after 5 seconds. So Get Lucky probably sounded like Justin Bieber sounded like Bjork after being stretched.

Very good true observation, Tony Zilincik. I’ve gotten really interesting results using all kinds of stuff, and feel that the least satisfying results (when trying to create sounds for my own use) come from stuff that is beat-heavy &/or heavily compressed. The (generally) more sparse, dynamic source files seem to result in stretched output files with loads more timbral contours & magical tones. A lot of those random, miraculous little tones that might pop up for a second can so often inspire a whole piece or song.

How hard would it be to port Paul’s amazing soft synth zynaddsubfx to os x? I may have asked this already. I would be willing to help. I’m running os x mavericks w/ newest version of Xcode.

I haven’t looked at how hard zynaddsubfx would be. If he used the same cross-platform libraries, probably not too bad.

I really wish the FLTK people would do a proper 64-bit port; PaulStretch is stuck in 32-bit land because FLTK uses a legacy Apple toolkit.

Check your source files.

Firstly, some of the libraries used do not like WAV files that contain meta-data of any kind.

Secondly, keep them 16bit. If you want headroom then resample to 96K and downsample afterwards.


Other people have fixed the static by changing audio devices. I’ve never encountered it.

Any chance this will be ported properly to Cocoa? I ask because the save dialogs are really annoying to work with.

Can’t be converted to 64-bit/Cocoa, as it uses FLTK 1.7, which can’t handle Cocoa. Sorry!

Hi guys. Has anyone encountered problems getting this version of Paulstretch to work with different audio devices. It for some reason will not pick up my Presonus audio interface, and will only play through the mac speakers. I’m using 10.6. Is there a hidden preference option somewhere where one can select the audio output for PaulStretch?

Thanks lads!

I’m getting the static (stuttering popping sound) when I preview, but it doesn’t end up in my final tracks. It’s happening with all my output devices. I’d seriously pay money to help this issue go away. Any plans to tackle this?

Why can I only export 43 seconds of the stretched audio file? Is it a bug or is it just me?

For a slighter smoother sound…

If you are not afraid of using the terminal then the python scripts are here:

You will need to install the numpy and scipy libs, and preferably a newer python than the system python.

You can use home-brew to do it easily enough:

brew install python
pip install numpy scipy
python -s10 -w1 infile.wav outfile.wav

WAV files cannot contain metadata, and need to be 16bit, sample rate can be >44.1k.


Sorry to come off as a complete newbie, but can someone please explain how to install this. How exactly do I run

I have recently started learning about the terminal, scripts and command line, but I am not beyond the basics yet. Thank you.

Do you have the OSX build source up in a repository somewhere? Would love to try my hand at making this a 64 bit beast…

You’d need to redo the whole user interface because FLTK is 32-bit only. But the source is on github.

Thanks for sorting this version out! I’m trying to think of a way to do batch processing with Paulstretch on Mac at the moment. I have a huge project I’m working on and would like to be able to process multiple files in one go without having to go in and out Paulstretch all the time.

Unfortunately I’m not too clued up on the coding side of things and that sort of stuff. Do you have any suggestions for a way of making this build of Paulstretch work as an offline batch process? I’m thinking it might be possible to do this using Automator or terminal commands but I’m not sure where to start…

If you download the PaulStretch on, I believe it has a python scripting interface.

HI there!
someone should rebuild paulstretch for osx 10.9 and later..
It seems to be a very fun app!


hi – – thank you for doing this job such a long time ago – – 2.2.-1 (20110305) is still working on OS X El Capitan (10.12.2) on a iMac Mid 2010 – – with a 32bit 48Khz WAV file – sounds absolutely great – – for those who are interested ;) – – the CMake version of the latest does not like to be complied – it is missing files – – – if like to hear – go to with https in the front – –

I’m sure this program is brilliant. For people who know what they are doing. Which doesn’t include me! I have a small sound file that I want to make exactly 1s in length. Currently it’s 0.914 (ish) seconds long. Is this the right program to use? In truth, even just padding it would be enough!

This would be a terrible program for stretching short audio files by a small amount. Better off using a regular audio editor’s timestretching.

Hi there, I just downloaded the program and can confirm that it runs fine on macOS 10.12.5 (Sierra).

I’m using it to recreate Leif Inge’s 9 Beet Stretch, a 24-hour-long version of Beethoven’s 9th Symphony. (http://www.læ – the original project is unavailable except for a barely functional live stream.) I’ve only done the first movement so far. I just used the default Paulstretch settings and stretched the file by 22.42x, which (if my math isn’t faulty) will stretch the performance I’m using to the target 24 hours, roughly. Sounds great!

Thanks for compiling this for OS X (now macOS)! Here’s hoping it continues to run under future versions. Cheers.

I don’t know about AIFF files, but a limitation of saving super-long pieces is that there’s a 4-gig limit on WAV files. You can save longer FLAC or mp3 files…

hey! I love PaulStretch. Got a new Mac Sierra 10.12.6 and the dmg doesnt want to run. It just does nothing when I double click it. Would be appreciated if you could have a look. Thanks. Matt Black

unfortunately I no longer have access to an OS X box to do further development.

The tools are out there, why isn’t anyone else interested in making this work?

Just open DMG in Finder and move “PaulStretch” folder into your “Applications” folder, just like you would normally do with any other app to install it. Then run “paul”. It runs fine on my High Sierra, so I guess it should work for you too. ;)

i am so friggin sad right now…. all I want is Paul’s Time Stretch… how can we get this going again??????

Hi, everyone. How do I install this on a 10.9.5 OS. There is no dmg file and I’m a bit clueless on how to do the installation. Thanks for the advice

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