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Resampling in DrumGizmo

Posted: Sun Jul 16, 2017 8:04 pm
by parhom

I have noticed an issue connected with resampling. I use 96kHz 24bit jack session with Reaper and the sample rate of Crocell kit samples is 48 kHz. When monitoring (or rendering audio to other than 48 kHz sample rates) I can hear some noise in high frequency range. When using 48 kHz jack session or rendering mix to 48 kHz everything is fine. I tried recompiling DrumGizmo with libsamplerate instead of zita-resampler, but it was too slow and produced a lot of xruns, making DrumGizmo not usable. Also I tried DrumGizmo on Windows 10 with Reaper and had absolutely the same results - the noise was there in case of resampling. The only way to have clear sound now is using session with sample rate that equals to the sample rate of the drumkit and render mix also with same sample rate. Upsampling or downsampling with DrumGizmo produces the noise.

Is that some kind of bug in resampling or something wrong with my configuration? I'm not sure, but maybe it's kind of aliasing and the solution could be using a lowpass filter before resampling?


Re: Resampling in DrumGizmo

Posted: Sun Jul 23, 2017 9:35 am
by deva
Could you describe the noise in more detail? Is the noise something you can hear? or something you can only see on a frequency spectrum?
Is it a hissing noise or more like a repetitive stuttering?

Which buffersize do you use? very low latencies (<5ms) can sometimes result in stuttering noise. Especially when resampling to such high samplerates as 96kHz.
Does the noise change its main frequency if the buffersize is changed?
And finally - can you also hear the noise if you bounce the track (not sure if that was what you meant by "rendering")? or is it only present when you play real-time from the DAW?
(BTW: You can use libsamplerate even though the CPU is not fast enough. When bouncing the processing is not real-time so it will always produce sample perfect output regardless of the CPU power available)

Oh... an another thing. Another user reported some stuttering when the midi editor window is open. Closing the window solved the issue, so we concluded that the issue was due to a bug in Reaper and not DG.

Re: Resampling in DrumGizmo

Posted: Mon Jul 24, 2017 10:17 am
by parhom
It's kind of clipping sound, that is present only if the sample rate of my session (or the mixed and exported to WAV track, I meant that by 'rendering') is not equal to the sample rate of Drumgizmo kit's samples. And it is present when monitoring AND when exporting (in the resulted track). And, for example, if the session sample rate is 44.1 kHz but the export track has 48.0 kHz, the noise is present only when monitoring and vice versa.

I've even tried to resample all Crocell kit samples with sox to 96 kHz and it worked: there was no noise in sessions with 96 kHz sample rate. But it has eaten nearly 16 Gb of RAM when loaded to Drumgizmo.Though I haven't tried exporting it.

My Jack settings:
Sample rate: 96 kHz
Frames/period: 256
Periods/buffer: 3

I have Ryzen 7 1700 processor with 32 gigs of RAM and M-Audio Audiophile 2496 sound card.

And also the issue is present on Windows 10 with Windows versions of Reaper and Drumgizmo.

I attached exported kick tracks without any FX, so you can hear it yourself (the clipping noise occurring in 44.1 and 96 kHz tracks):
48.0 kHz ... sp=sharing
44.1 kHz ... sp=sharing
96.0 kHz ... sp=sharing

Re: Resampling in DrumGizmo

Posted: Mon Jul 24, 2017 12:23 pm
by parhom
I'm using 0.9.14 release and with diskstreaming it seams to work OK. But with other kits (or their normal sample rates) I even don't need to use that feature, because I have enough RAM. Anyway, that seems to be some kind of bug in resampling so I decided to report it, because it makes using Drumgizmo not so comfortable (I mean having to manually resample the drumkits or to use lower session sample rates). I can be wrong and the issue may be not with resampling. It seems to be especially noticeable with fast kick tracks. Though I don't have any xruns in Jack and any underruns in Drumgizmo window. And the issue is not there when resampling is turned off.

Re: Resampling in DrumGizmo

Posted: Mon Jul 24, 2017 12:28 pm
by deva
It does indeed sound like a bug in the resampling code. I'll do some analysis and get back to you once I know more about the issue.
Thanks for reporting :-)

Re: Resampling in DrumGizmo

Posted: Wed Aug 08, 2018 4:43 pm
by deva
We have refactored the entire resampler code in order to fix this.
You can download the VST dll to test it here: ... in64/1349/
We will be releasing the new bugfix version soon so if you could try it out and tell us wether it solves the issue for it would be most helpful :-)

Re: Resampling in DrumGizmo

Posted: Sun Aug 12, 2018 9:48 am
by deva
This is expected to be fixed in the 0.9.16 release. If not. Please comment.