So one thing that I’ve noticed with speeding up clips in Kdenlive is that it also makes sped up voice audio sound like it gains a faint echo or reverb - I don’t really know what to call it. I’m sure you’re all familiar with it if you use it on a regular basis. It also tends to really screw up the voice audio if you speed it up past x2.1 the original value, such that getting tolerable results requires rendering the sped up clip independently & importing that into Kdenlive to make it more than x2.1 speed without serious sound issues.
If possible, I’d like the sped up audio to sound more smooth, maybe like the way Youtube audio sounds no matter how high you put the speed settings at. Is this achievable in Kdenlive? Does anyone know of a solution to this?
I tried playing around with various sound effects to see what could be causing this, and the closest way to replicate what sped up clips sound like that I found was the Flanger effect, but it’s still not exactly the same, and adding it to the sped up audio & changing the parameters doesn’t really get rid of the echo / reverb from what I’ve tried.
Anyone know a solution? And/or what the effect is called that occurs when the audio is sped up?
Hello @SonNormW25,
what do you use to make the speed changes? If you use Clip Speed, then it makes a big difference whether you turn on Pitsch compensation or not.
It could also be that your audio material doesn’t give more. How does it sound when you do the same with Audacity?
It’s the Clip Speed panel, yes, and I always use Pitch Compensation as well. It’s not the difference in pitch that’s the issue but the way the voice sounds a bit…reverbish. It’s not an echo strictly speaking but the way the audio comes through sounds like it’s a bit filtered through something, and kinda similar to what the Flanger effect does.
To clarify a bit more, I’m mainly looking for a way to make sped up audio sound as smooth as a Youtube video at 1.5x or even 2x speed, whereas in Kdenlive you get a sideffect where sped up and pitch compensated audio still sounds…iffy, filtered or Flanger like.
Correction: I do the speed change by right-clicking on a clip in the Project timeline and clicking on Change Speed which brings up the panel.
Here’s also a 30 second video comparison of the difference in sped up audio between Youtube speed settings and Kdenlive, both at 1.75x speed, yet Kdenlive sounds…less smooth?..a bit filtered?..Flanger like?..than the screen recording of the same video:
Not a typo. I am using the older version since I don’t want to upgrade just yet. Has this audio sound of sped up clips (well it’s not really an issue as it can easily be ignored, it’s just a minor effect on the audio that some may dislike) been improved in the later versions?
Hi, I am facing the same issue. I am on 24.12.3 and when I speed up a clip using pitch compensation my voice sounds a bit funny, it seems that the algorithm introduces some tiny reverberation. Is there any way to fix/improve that?
There almost surely is, even though it can be hard (technically it’s impossible in the general case) to prevent some amount of ringing in some samples with this sort of signal processing.
But kdenlive doesn’t implement this itself - we pass it off to MLT, which in turn appears to pass that functionality off to this library: Rubber Band Audio Time Stretcher Library
So to improve this, the first step would be to ensure your MLT build is using the best version of that library possible, and if pain persists either look at improving that library or find a suitable better replacement for it that MLT can use instead.
Any improvements there will automatically bubble through to future builds of kdenlive.
Thanks Ron! According to Kdenlive, it is using MLT 7.30.0 which seems to be the latest. I went to the Rubber Band website and I can see its latest version is 4.0.0. Since I am running a flatpak version of Kdenlive, I believe I can’t update anything inside it.
It’s possible the 4.0 release brings some improvement to this, but from what I saw (without looking at the actual code), it seemed that was mostly about adding a new simpler API, I didn’t see any announcement of algorithm improvements …
Hello Ron, I have some intriguing news. I have tested the latest version of kdenlive (25.04.3) on a Windows 11 machine and using the same raw video source, the sped up video rendered on Windows is completely clean but the same video sped up to the same speed when rendered on Linux (kdenlive 25.04.3), has the reverb discussed here. Now what intrigues me the most is: MLT version on Windows version is 7.33 and on Linux is 7.32. According to MLT website the latest version is 7.32 so how come kdenlive on Windows is using 7.33? How can I get it and install on Linux, any clue? I have used the standalone Windows installer.
The current MLT ‘release’ is indeed 7.32 - but when fixes go into MLT for some issue seen in kdenlive, the craft builds are sometimes tweaked to use a git snapshot of MLT that is not yet tagged and released.
It looks like that happened this time somewhere between building the Linux image you tested and the final release candidate for Windows.
Curiously I’m not seeing anything immediately leap out at me which would affect this and it still seems to be using the same version of RubberBand …
How can I get it and install on Linux, any clue?
If you want 25.04.3 built with a different MLT, you’d need to build it yourself - but you could try the current nightly appimage (which is freezing/branching for the 25.08 release today), which should be built with the updated craft recipe and MLT version.
If that doesn’t also ‘fix’ it - then we need to look at what else might be different for the windows build, but this is indeed interesting. Thanks for keeping an eye on it!
Ok, update to this. What linux build are you using?
I just checked the 25.04.3 appimage and it looks like it’s using the same MLT as the windows build.
Moral of the story (again!). Always test with the AppImages before reporting problems here.
(and really, always just use them unless you actually like problems …)
Update: I was using the flatpak version of kdenlive (25.04.3)… And guess what? Yesterday I tried the appimage and the reverb is gone! I am not sure why my flatpak version had the issue and appimage doesn’t but in any case, I believe the problem is gone now! Thanks!
