OctaChainer v1.3

OctaChainer is a Windows and OS X tool for creating sample chains and slice data for the Elektron Octatrack and Analog Rytm. New in this version is a new “Megabreak”-mode (explained further down), a redesigned UI with a tab for each mode and options for normalization, fade-ins and outs.

NB: a newer version 1.3.1 of this tool is now available.



You might get warnings from the OS telling you the program isn’t signed or not from the App Store. Also, the GUI will not scale well in windows on a high-DPI screen.  Right click on the .exe file, go to Properties -> Compatibility. Check “Override high DPI scaling” and set “Scaling performed by” to “System”.

How to use this tool

The Octatrack stores metadata for samples in “.ot” files. Those files contains various sample settings, including data for slices. This tool can generate those files alongside the actual .wav samples. Octatrack users should copy both the .wav and corresponding .ot file to the Octatrack. Turn on slice mode, and the slices will already be there.

There is no corresponding metadata file for the Rytm, nor do the machine support slices in the same way as on the Octatrack. Rytm owners chain samples by creating an evenly spaced grid and then using the sample start parameter on the machine to select which sample to play. OctaChainer have a dedicated mode for this use as well.

Note: This tool will convert bit depth and between mono and stereo. It will NOT resample the audio when changing sample rate.

Octatrack slices mode

Main mode of OctaChainer. Loaded samples are saved as a single samplechain with a corresponding .ot file

This is the “main” mode of OctaChainer. Load a collection of samples, arrange them in the order you want and generate one long .wav file with a corresponding .ot file containing the slice data and whatever settings you have set in the “OT Attributes” section. The text in brackets in the sample list indicates if a loaded sample is mono or stereo, as well as sample and bit rate.

You can optionally choose to normalize each slice separately or the final audio file as a whole. You can also set a short linear fade-in or out per slice to help avoid audible “clicks”. The “Add silent slice” button adds a 1 second silent slice. You can use these as place-holder slices or to make sure, say, a collection of drum kit chains all have their snares on a specific slice number.

Evenly spaced grid mode

Evenly spaced grids for Rytm users

This mode is mainly for Rytm users. It will generate an evenly spaced grid where the longest loaded sample will dictate the length of each sample in the grid. All shorter samples will be padded with silence.

Rytm owners will need to generate a chain with a sample count that 120 is divisible by. The “Add silent slice” option is therefore useful to bump the total sample count up to a usable number. An .ot file can optionally be generated too, for those who own both machines and want to use the same chain on both.

Slice per X step of BPM mode

This mode generates slices of a length given in steps. It is calculated from the indicated BPM.

This mode is for Octatrack owners only and is a bit trickier to explain. It does not generate an audio file, just .ot metadata. Imagine that you have a long sample of arbitrary length. It could be a backing track, for instance. If you want slices that are each, say,  exactly one pattern long, this mode lets you do that.

Load your sample, set the BPM and select how many steps you want each slice to be. Hit generate and an .ot file will be created next to the audio file you selected.

The “Include tail” option lets you decide if you want a slice for whatever is “left” at the end of the audio file after the last full-length slice.

Megabreak mode

Reorganize samples for the so-called “Megabreak of Doom” method.

Several years ago, inventive Elektronauts user “wascal” came up with a very clever way to reorganize slices and explained the technique in this thread. In his video demo he uses breakbeats, but it works well for melodic loops as well.

I’d check the thread for details, but the basic idea is to take a selection of samples, slice them all into the same number of parts, and then save new audio files, one with the first part of each source sample, the next with all the second parts, etc. The purpose of this is to be able to use modulation or the crossfader to move between samples.

Finishing off

The tool is completely free and the source code available as public domain. If you like it, I’d appreciate if you took the time to check out our music. Any shares or other form for support would be most appreciated.

There might be bugs. If you find any or have ideas for new features, feel free to comment below. I seriously doubt that using this tool can harm your Octatrack in any way, but use at your own risk.

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37 thoughts on “OctaChainer v1.3

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  1. The app crashes everytime when I put in 64 short stereo samples in 24bit/44.1Khz and try to chain them in Octatrack Slices mode with slice normalization, 1ms fade in and 10ms fade out.

  2. Hi

    I’m on windows (10) and drag’n’drop isn’t possible. It’s bit trickier than in 1.2 version this way.
    Any hope of fixing this. Thanks a lot:)

    1. I think it would be a very easy fix. The reason it isn’t there is simply that I never use drag’n’drop myself and had forgotten that it used to be there!

      1. drag’n’drop would be welcome on the mac os version as well 🙂
        oh .. and a ‘clear all’ button (or at least be able to CMD+A to select all) would be cool !
        thanks a lot for this great lil app

  3. Hi, thanks for this great app. I do not understand how to use the magabreak mode because of what could be a bug.
    When using 16 samples splitted in 16 everything works as expected. But when I try to use 64 samples the software outputs only 16 slices. If I ask for 64 output files then I have the correct amount of slices but of course 64 files instead of 16…I know other people on elektron forum have mentionned similar issues. Is there a way to output 64 samples matrixed in 64 slices X 16 files ? Thanks a lot for your time.

    1. Yes, I saw sezare56 on Elektronauts discovered that it wouldn’t output more than 16 files max. So it must be a bug, but I never got around to looking into it. It is likely very easy to fix, so I have been meaning to fix that and the drag&drop functionality for quite some time now. But for whatever reasons I have never gotten around to it. Sorry about that! I’ll try to get it done soon. Nice to know someone finds the megabreak mode useful. 🙂

  4. Amazing app! Wondering if you can have a mode where you can drag more samples than the 64 and then it makes multiple stems? That way you don’t need to count the samples to make stems. Hopefully this makes sense.

  5. Hi, I have some chains I sampled manually (they´re SEGA Genesis sound effects, maybe 37 or 39 sounds sampled one by one in a file). What is the best way to create the slices or the .ot file?

  6. Hey there!

    Just used this app on longer samples and it worked perfectly. However, when trying to use it on very short samples 1-2 seconds, it did not seem to correctly create the longer audio file.

    1. Thank you for the bug report! Do I understand you correctly in that the combining short (1-2 sec) samples and very long ones (would that be 5-6 minutes, perhaps?) in the same chain doesn’t work properly? I don’t think I have ever tried that myself. I will look into it if/when I get around to fixing some other reported issues. (Drag&drop isn’t working and more than 16 samples in megabreak mode doesn’t work, either). I have been meaning to fix these for a long time, but for whatever reason I keep putting it off…

  7. No matter what files I use and what mode, this app fails to create correct output. The WAV file is always 44 bytes long! On Windows 10, using latest version.

    1. Hmm. I have no idea why, unfortunately. I haven’t heard of anyone else having this problem, either, so I have nothing to suggest. Sorry. 😦

      I initially made this as a quick-and-dirty tool for my own use, but when others found it useful I added some more features and tried to make it a bit more user friendly. But it is not a robust piece of software. Very little error-handling, no logging of problems, etc. So when something unexpected occurs it just crashes. That makes it really hard to track down issues that I’m not able to replicate at my end. One of several issues I should fix if I do a new version, but something I’m unlikely to get around to at this point…

  8. OK, understood. I really have tried every single option, every type of file, as well as using version 1.2. All efforts produce an OT file and the 44 byte WAV, though with no crashes as such. It does seem that I am the only one with this problem, even though my Windows 10 install is standard and I regularly use an rather large suite of audio-visual software with no problems (Reaktor, Max, Samplitude, DaVinci Resolve, etc.) Ongoing discussion here:

    Can you share or point me to documentation for the OT file format? I can’t quite understand the C++ code. I am thinking that it would be great to have a utility that converted standard DAW output.

    In the meantime, I am creating equal-size slice files myself in Samplitude. Which works, but wastes OT memory.

  9. I’m not getting any audio from the playback on Windows 10 (x64), it doesn’t seem to be doing much of anything, though I can add files to each type of output. Does the build need updated Qt dependencies or something?

    1. Not that I know of. I’m using the OS X version myself, so something might have changed without me noticing. I have seen others mention playback not working for them as well, but I haven’t investigated. It should still output a .wav/.ot file, though.

  10. I just started using the software, really great so far. I have two suggestions. One, is it possible to select more than one sample at a time from the list? Removing them one at a time is very tedious, as is opening and closing the program to reset the list. Second is confusing for me to explain, but I’ll try. Instead of loading 64 samples from a folder containing hundreds, being able to load the full folder and have OctaChainer output them in chunks of 64 would be really handy.

    1. Thank you for the suggestions! No need to close the application, you can use File -> New (or something similar, I don’t have it in front of me).

      Multiselect when deleting sounds useful. I also like your idea of the “add lots and create many chains”-feature.

      I am not promising I will actually do this, though. There are some bugs I have been meaning to fix for ages, but for whatever reason I haven’t done so yet. Sry, I’ll try to get around to it.

      1. Ah, I didn’t know about File > New, real time saver, brilliant.

        I’m not going to bitch about free software which actually works just because it doesn’t have some feature I’d like, OctaChainer stopped me from smashing my head against the wall trying to get GTBG to work. Cheers for the efforts, Kai.

  11. I’d like to suggest the format .rx2 for a future update. It carries info about slices, number of beats, BPM and more.
    That would be a great fit if OctaChainer could process these info and sort out the OT file according them..

    Keep up the good job and thanks for your input in the OT community 😉

    1. That was actually the original idea for the tool. I sliced up some loops in ReCycle and wanted them on the OT. But the format is proprietary and requires a registered reason dev company, licence, etc. So at the time I decided against it. It would be an excellent fit, though. I might check with them if a licence is possible for a public domain hobby project like this.

      It would mean linux support is dropped. And anyone wanting to build from source would need their own licence, I suppose. Perhaps a separate «rex to ot» converter tool would be best?

  12. Amazingly helpful tool. Thank you so much for creating and sharing it!

    I’d like to +1 the multiple-select suggestion. Yes, useful for deletion but also the first step towards “load a stupid amount, select N files and export a chain of N slices”

    1. Glad you like it! I added multiselect (and multiple chains when more than 64 slices) as suggested by Loadout in the recently released v1.3.1 linked to from the top of the blog post, btw.

  13. Hi Kai, thanks for the great tool. Would like a feature to edit end/start points for Slice per X step. This could be for all or individually. Perhaps a list of of the slices with start and end time, that we can edit, for each slice just before you can click create. If you really want to get crazy it could have loop point time for each slice too. This could also be a feature for the other slice modes.

    Should you like a UI designer for an interface with sliders rather than text input boxes, hit me up.

  14. The APP Crashes every time for me now, and I do not know why.. All bitrates and sample rates are correct meaning no converting is happening. It worked fine for me for first month and now a crash everytime in use in regular OT slice chain mode. I am using MBP MacOs 10.15.17.

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