Bug detected:

Submitted by G3N-es on
Forums
Qtractor

  1. Create a new session without a template.

  2. Create a track.

  3. Import audio.

  4. Select the clip.

  5. Set the clip to loop.

The audio becomes inconsistent, randomly appearing and disappearing.

  1. Insert an audio plugin into the track.

The problem disappears.

Submitted by G3N-es on Sun, 3 May 2026 - 15:41

Permalink

I had similar problems before (about a year or two ago) with FLAC formats and stopped using them.

This was OGG. I'm slowly creating loops and other resources for myself, and also for the possible distribution of Qtractor with preset samples and more...

I've attached an example file.

PD:
I just checked, and if I shorten the range, it also disappears. Also if I stretch the clip out of range (no capitals).
It also appears if I export the same OGG file (or merge it as a WAV), but it doesn't happen with other WAV files... it's very strange.

I'm sure you'll also see the error with that file. It was created with a clean Qtractor configuration, intentionally reset. The problem appears in both compiled Qtractor and AppImage.

File attachments
error.qtz

Submitted by G3N-es on Sun, 3 May 2026 - 17:06

Permalink

Thanks to both of you for checking it out

PS:
I have a Linux Mint installation for testing, and it works well there.

PS2:
I was wrong, it does appear in Mint, but it takes longer to appear and is smaller.
Anyway, if you don't notice it, I'll consider it closed.

Submitted by rncbc on Mon, 4 May 2026 - 13:19

Permalink

I wouldn't dismiss or close the case so fast...

might be something in your computer(s), yes but also something in your system and/or custom settings or configuration that might be of interest to identify.

seeya

Submitted by rncbc on Mon, 4 May 2026 - 15:06

Permalink

The problem occurs with PipeWire sample rates above 256.

sample rates? or is it buffer-sizes ("quantum" in PW parlance)?

@bluebell spoke about "big buffer size"s above 2048 (frames/period) not sample rates :S

I meant "buffer size"/Quantum, right, I got the terms mixed up while typing, not while reading and understanding... XD.
I stand by my statement. Apparently, @Bluebell also notices it in Jack, but with much higher buffer sizes.
In PipeWire it manifests from 512 (frames/period) upwards, at least in my configurations..

Submitted by rncbc on Mon, 4 May 2026 - 17:09

Permalink

In PipeWire it manifests from 512 (frames/period) upwards, at least in my configurations..

nope, here after doing
pw-metadata -n settings 0 clock.force-quantum 512
and
pw-metadata -n settings 0 clock.force-quantum 1024
nothing strange happens, that meaning business as usual.

however,
pw-metadata -n settings 0 clock.force-quantum 2048
is a dang showstopper: can't get it to playback even at all, but that's probably due on my PW configuration having this property default.clock.max-quantum = 2048 so I wouldn't complain :)

check your pipewire.conf (and jack.conf) then, I'd suggest.

byee

It might be an issue on slow CPUs only. Jumping back to the beginning of the loop seems to have to decode part of the compressed audio file (more with big buffer sizes) in no time.

Submitted by G3N-es on Mon, 4 May 2026 - 19:05

Permalink

Probably. If anyone else encounters this problem, we already know the solution. It's simple.

Lower the buffer size.

Or extend the clip's duration; this seems to increase the sample size to be loaded, making it sufficient to prevent the issue.

Or insert an audio plugin... which apparently calculates the buffer size for the entire track.

At least those are the explanations my head comes up with for why the error doesn't occur that way :)

Submitted by G3N-es on Wed, 6 May 2026 - 12:34

Permalink

https://www.rncbc.org/drupal/index.php/node/2829
"ALL internal processing (within qtractor premises that is), plugins and looping included, is frame/sample accurate; automation being the exception as it runs on a fixed 64frames resolution (or even less, if the period buffer-size is insanely shorter than that)."

If I increase the clip duration by just 23 frames (the minimum allowed), exceeding the range limit, the problem disappears.

It might be a rounding error, resulting in an empty sample space.

As I mentioned, it's not important, but... it doesn't hurt to point it out.
It might also be related to the desynchronization (although that disappeared with a generic kernel on my machine) of audio tracks in loops...

PS: Sorry, I misunderstood. Everything syncs to 1 frame, except for automations, which run at 64 frames.
It can't be a rounding error then.

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