At the moment the quality of time stretched audio clips is better with WSOLA than with rubberband when I use a factor of 1.5.
Since modern version of librubberband have a v3 API the quality can be increased. It's a bit confusing that – for example in Debian Bookworm – the lib is called librubberband2 with version 3.1.2 and the actual library is called librubberband.so.2.2.1. But there are 2 CLI tools: rubberband and rubberband-r3. So there is alreade the v3 API available.
I made tests with the command line tools, Qtractor's on-the-fly and Qtractor's function to create a stretched version with Clip->Merge. The version made with rubberband-r3 is the best and has no crackles in it.
Is it possible to use the v3-API in Qtractor?
Qtractor test session: http://suedwestlicht.saar.de/secdnld/stretchtest.qtz
re. Improve time stretching quality...
hi, maybe missing something in this regard...
on my knowledge, it all dependeds onto which rubberband library it is built...
let me say that, from the repos (libs), it's currently the latest v4.0.0 (librubberband3, yes confusing:))... but it really boils down to the above: which librubberband was your qtractor built/linked against, may I ask?
or iow. as I think you're on a ubuntu/debian base system, the question goes to which librubberband-dev version have you installed?
cheers
rubberband-3.3.0
I compiled and installed 3.3.0, the latest v3 before v4. It's the only librubberband on my system and Qtractor on my system is built with this lib as well as I used rubberband and rubberband-r3 CLI.
re. rubberband-3.3.0
ok, understood
please tell the exact parameters to rubberband-r3 (cli) you use to get the better results?
seeya
v2-quality: rubberband -2 …
v2-quality: rubberband -2 -t1.5 a.wav a2.wav
v3-quality: rubberband -3 -t1.5 a.wav a3.wav
The only difference was forcing v3 mode.
I think you don't have to…
I think you don't have to change anything except for using OptionEngineFiner at the constructor.
While you at it: how about…
While you at it: how about making a check box for formant preserving when changing pitch? :D
re. While you at it: how about…
that and the other option will need changes on the main Options and (audio) Clip properties and dialogs, for sure...
not impossible, just takes some more time ;)
re. Improve time stretching quality...
can you tell whether this v1.5.2.7git.5b935a [develop] is a good move?
warning: caveat emptor (as one can read from
rubberband-r3 --help...);)
I hear no difference
Sounds if it's not using the finer algo. I tried on-the-fly and merging the clip.
double checked
I compared the new merged clip with the old clip in Audacity. When inverting (180° phase flip) the new clip they cancelled out each other perfectly.
re. double checked...
right, nothing really changes if you're still on rubberband v3.3.0, my mistake sorry
later today it will be fine though
stay tuned
I could compile & install v4…
I could compile & install v4 but I think most distributions have v3, so it's worth the effort I think.
re. rubberband finer R3 and formant preserve...
all tamed now in qtractor >= 1.5.2.8git.4db20c
hopefully :)
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