- Apr 11, 2010
Man that song is the poster child for "swish", a good find. I will add to my torture tracks for trying to eliminate the swish.I think I need some help with SW2. I tried playing using the -m4 option but I'm still hearing artefacts, swishing from about the 22 sec mark in the test file
Glenn, can you suggest settings to remove the swishes, drums and guitars from 22 sec mark?
Both upmixes sound great until 22 sec mark, then SpecWeb starts swishing like crazy.
I think they used some crazy stereo widener on that track, because in stereo stuff is clearly coming from left of left and right of right, although it doesn't show up as funny on a phase meter. I might try "narrowing" the mix, before spreading it back out with SpecWeb, just to see what happens.
Anyway to answer your question as to settings, I came up with the attached (rename to remove .txt extension), and then you can add in -m4 on the command line if you like.
I'm not saying it's a complete solution, but then I don't think I found the same source as yours (mine is 44.1K 16bits).
Longer version is:
"Swish" is a known artifact of Phase Vocoders, the way Spec and SpecWeb move sound from the time domain to the frequency domain and back. When/If I find a better way (which may just be DSP techniques I don't grasp yet) I will change it and not look back. At one point I completely ported a different method, fast hartley transform vs. fast fourier transform, from "CenterCut" from C# to C++ but it ended sounding exactly the same (the time to frequency and back part, not the "CenterCut" method itself).
"Swish" with phase vocoders happens with "Noisy Transients" like certain cymbal sounds. Normally these are tamed with the upsample --> upmix --> downsample technique but for some songs, like this one, it's not a complete solution.
So, in this case the next thing you can do (if 2x and 4x upsample don't help) is trade off separation for a reduction in artifacts. There are a bunch of controls in Spec/SpecWeb for this. Mainly Adjacent Speaker (mixes in sounds from the speaker on either side, e.g. mixing some RF and LS into RS) but probably more applicable to this case mixing some of the original stereo back into the rear channels, with the LS and RS Blend controls.
As I said, this is trading off artifact reduction for less separation so at the end of the day you might have waveforms that look/sound similar to Penteo, I guess.
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