About Rhythm Ferret

TL;DR at bottom :wink:

Background story

So last Saturday during my (now online) Audio Engineering course we did a little comparison of some well-known DAW's to see how they handle things differently. The task at hand was: how to align (or "quantize") a drum track to a grid / tempo map. Think of equivalent workflows to PT's Beat Detective.

Our session had several drum tracks recorded using a click track (kick in/out; 3 toms, top/bottom snares, hi-hat and left-center-right overheads).
Granted, we didn’t compare Ardour per se but rather Mixbus 32c v6, but the Rhythm Ferret module is exactly the same in Ardour AFAIK. I tested the workflow on my own system - with Ardour & MB latest versions - and experienced the same results.

  • Course PC spec: Mac OS 10.13.6 | Intel Xeon 6-core 3.46GHz | 64GiB RAM
  • My PC spec: openSUSE Leap 15.2 kernel 5.3.18-preempt | AMD FX-6300 6-core 3.2GHz | 8 GiB RAM | AMD Radeon RX 550


We selected Percussive mode, set Sensitivity to ~70 and Cut Pos Threshold -40dB or so, and pressed "Analyze"...Which. Took. Ages...There's no real progress indicator, but eventually we got a result which was sub-par at best (lots of misses in the beginning, too many hits at the end). After a few more (frustrating) tries we just hit "Apply" and... MB promptly crashed.

I recreated this scenario on my home setup with Ardour and got the same problems except for the crash. But the whole Rhythm Ferret “Analyze” was rather slow, and even with an analyzed audio track played on click it still can be difficult to get a workable result out of it.


I did manage to get my regions split up into 100s of small little regions, but now the whole session is just unusable. I can barely get it to open and render, and actions like zooming, selecting regions etc... is a real drag now. I tried combining the regions again but I constantly run out of patience :smiley: It doesn't seem to me that analyzing the audio first (for transients) improves the process, although I always do just in case.


  • Rhythm Ferret can be a lot of “hit 'n miss” to get it right, fair enough. But since analyzing can take a very long time and there’s no real progress indicator if the process hangs or not. This is purely a visual thing. Is it feasable to display a warning message that the process can take a while; or actually show a progress bar ? Anything that warns the user so he can cancel out ?
  • When you end up with lots of small regions, the whole session can be unusable (open, zoom, edit, selecting regions… all very slow). Since you don’t get an indication if this outcome is possible, when you get this far it’s already too late. Is this hardware related ? Can Ardour internals be improved or is it a combination of both ?

I’d love to hear some feedback on how to improve our workflow, speed up the process, suggestions, experiences…?


The ferret is too slow, I ain’t got time for that. I made a script to do it for my purposes (cutting samples)

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I guess nobody uses the ferret than. I’ll try your script, looks promising :slight_smile:

I use Ferret on occasion, but it is on an as needed basis for me. I can’t comment on your particular experience sadly, sorry.

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I never understood how to get ferret to work. And what’s funny is that one youtube channel, Spectre audio or whatever in canada, raved about it in his review of Mixbus. That guy usually just shits on everything, but he was really impressed by ferret. Imma give it another try this weekend.

Related side note: I feel like mixbus crashes too often :frowning: Ardour never crashes on me. I know the DSP usage is higher with the analog emulation and whatnot, but it still hardly taxes my resources.

That does not sound right. Are you using any plugins in Mixbus that you don’t use in Ardour?

It’s a 2 or 3 step process.
First the region is analyzed. That places transient markers which can be manually moved or removed if needed. Next step is to split the region at those transients (Ardour really splits just before so that the onset itself is not lost).
Finally you could for example select all the regions and use Region > Position> Snap Position to Grid to quantize it.

Sometimes however I find it more efficient to simply manually step though.
Select a region, Ctrl+ right-arrow jumps to the next onset. press ‘s’ to split as needed.

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Only the Harrison plugins. I also use your organ VST but I use that on both Ardour and Mixbus. It rarely crashes in the course of working on a project. Lately, it always crashes when I go to close a session or open a new session while working another one. I’ll have to start launching from the terminal so I can get some sort of output.

That’s the way I do it as well.
The problem is; this workflow really only applies to single tracks and / or short regions, so the manual work is limited.

In my OP, we had several tracks that needed alignment.
After analyzing we noticed that the transient markers were kinda all over the place.
The amount of manual work needed, makes the Rhythm Ferret a bit useless atm (in this particular setup anyway).

Not to mention that, if you “apply” and end up with lots of small regions, the whole session becomes impossible to work with. I’ve had this happen 3 times on 2 different pc’s in my testing. Just selecting the regions takes up several minutes.

Not trying to complain here, genuinely wanting to know if this can be improved upon ?
Shall I make a bug report or not ?


I’m having the same issue when dealing with many small regions. It’s is possible to join back the regions (reversible) once you finished to deal with them and that fixes the performance issue. That means you sometimes have to deal with tracks or portions of tracks one by one to ensure you never get too many regions at the same time :confused:

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This video can help:

Not very surprising. Each track is analyzed separately, and I’d expect that detection of hits is different depending for each drum and also mic.

For this specific case it would probably make sense to only analyze one track and also use this information to split others, especially in case of bottom/top mics of the same drum.

Maybe, probably, hard to say without further investigation.

One aspect is the onset/transient detection for which Ardour uses https://vamp-plugins.org/download.html – that is pretty much outside of our control.

Then there is this long standing issue:

Is there anything that can be done for 0002982: performance issue with lots of regions (bad scalability)? Or do we just have to get along with it. Smooth drum editing would be a spectacular.

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