>>Tips to enhance separation results<<
If you cannot achieve good separation, you can conduct the following experiments.
Some tricks might be outdated when using Roformers.
1. De-bass
Turn down all the bass to stabilize the voice frequencies of your input song (example EQ curves: 1 and 2).
Male setting: cut all below 100Hz + cut all above 8kHz.
Female setting: cut all below 350Hz + cut all above 17kHz.
This works, because jitter is reduced a lot.
2. De-reverb
You can also test out the de-reverb e.g. in RX Advanced 8-10 on your input song. One or both combined in some cases may help you get rid of some synth leftovers in vocals. Alternatively (not tested for this purpose), you can also try out this or this (dl is in UVR's Download Center) de-reverb model (decent results). Currently, the VR dereverb/de-echo model in UVR5 GUI seems to give the best results out of the available models (but RX or others described in the models list section at the top can be more aggressive and effective with more customizable settings).
3. Unmix drums
(mainly tested on instrumentals)
Separate an input song using 4 stem model, then mix the result tracks together without drums and separate the result using strong ensemble or single vocal or instrumental model (doesn't always give better results).
Alternatively, unmix bass as well. There’s great bass+drums BS-Roformer model released for UVR (currently in beta)
4. Pitch it down/up
(soprano/tenor voice trick + ensemble of both)
- You can use https://github.com/JoeAllTrades/SpectraDownshift for it
(it’s based on scipy, it’s lossless, so fully reversible and nulls), or:
- Already implemented option in newer versions of UVR under “Shift Conversion Pitch” in Settings>Choose Advanced Menu>Advanced [Arch] Options>
And there are positive and negative values when you scroll up and down
(lossy, even more than soxr).
Negative value will slow down the track before separation, so e.g. model with cut-off will be compensated for its band lost a bit after speeding up again.
If you slow down the input file, it may allow you to separate more elements in the “other” stem of 4-6 stems separations of Demucs or GSEP (when it’s done manually).
It works either when you need an improvement in such instruments like snaps, human claps, etc. The soprano feature on x-minus works similarly (or even the same), it’s also good for high-pitched vocals.
Be aware that low deep male vocals might not get separated while using this method (then use tenor voice trick instead - so pitch it up instead of pitching it down.
Also, it serves the best for hard paned songs (e.g. 1970 and pre era, e.g. The Beatles, etc). Also, it works great for drums. While evaluation on multisong dataset on MVSEP, it decreases SDR by around 1.
"Basically lossless speed conversion a.k.a. soprano voice trick done manually:
Do it in Audacity by changing sample rate of a track, and track only (track > rate), it won't resample, so there won't be any loss of quality, just remember to calculate your numbers
44100 > 33075 > 58800
48000 > 36000 > 64000
(both would result in x0.75 speed)
etc." (by BubbleG)
Q: Won't the result be sped up?
A: “No. Because when you first slow it down, after processing with said model it gets converted to 44100 again (only the sample rate, not the actual speed), so speeding it up brings the speed back to normal” becruily
Q: I don't quite get what I'm supposed to do though, just slow down the file to 0.75x and then export in 58800?
A: “change the sample rate to 33075 Hz,
then export at whatever sample rate
process then,
change the sample rate of the processed file to 58800 Hz
key word being change, not resample
like this, click other and the pick the correct samplerate” Dry Paint Dealer
4b*. If you have a mix of soprano and baritone voices, you possibly can do:
"1. Soprano mode (slow down sample rate), then bring back to normal
after that
2. Tenor mode (speed up sample rate), then bring back to normal
and finally combine the two with max algorithm"
Making an ensemble of such results can also increase the quality of separation.
“I have tried faking the sample rate both in 48k and 96k files. For 48k usually the results are satisfactory, because most models already are trained on lower pitches from augmentation.
But from 96k to 44.1k is such a long road, it simply doesn't work” - Michael
5. Use 2 stem model result as input for better 4-6 stem separation
You may get better results in Demucs/GSEP/MDX23C Colab using previously separated good instrumental result from UVR5 or elsewhere (e.g. MDX HQ3 fullband or Kim inst narrowband in case of vocal residues, or BS-Roformer 1296)
6. Debleed
If you did your best, but you still get some bleeding here and there in instrumentals, check RX 10 Editor with its new De-bleed feature. Showcase
More methods of debleeding stems.
7. Vocal model>karaoke model
You might want to separate the vocal result achieved with a vocal model with MDX B Karaoke afterwards to get different vocals (old model).
8. The same goes for unsatisfactory result of instrumental model - you can use MDX-UVR Karaoke 2 model to clean up the result, or top ensemble or GSEP like for cleaning inverts (old models)
9. Mixdown of 4 stems with vocal volume decreased for final separation
An old trick of mine. Used in times of Spleeter to minimize vocal residues.
Process mixture to 4 stems and then mix stems in a way that vocal is still there, but quieter, so lower their volume, and set drums louder, then send the mixture from it to one good isolation model/ensemble, so in result drums after separation will be less muddy, and possible vocal residues will be less persistent.
But it was in times when there wasn't even Demucs (4) ft or MDX-UVR instrumental models, where such issues are much less prevalent.
10. If you use UVR5 GUI and 4GB, you may hear more vocal residues using GPU processing than e.g. while using 11GB GPU (tested on NVIDIA). In this case, use CPU processing instead.
11. Fake stereo trick
Aufr33: “process the left channel, then the right channel, then combine the two. [Hence] the backing vocals in the verses are removed” (it still may be poor, but better). “I'm having to process as L / R mono files otherwise I get about 3-5% bleed into each channel from the other channel, but processing individually, totally fixes that” -A5
On an example of Audacity: import your file, click on down arrow in track selection near its label, click Split Stereo Track, go to Tracks>Add New>Stereo Track.
Mark the whole channel, copy and paste on one of the tracks you divided before.
It will overlap the same mono track in stereo track, so the same across both channels.
Do the same for both L and R separately. Then separate with some model both results separately. Then import both files and join their separate channels by method above. Don’t confuse L and R channel while joining both.
12. Turn on Spectral Inversion in UVR
it can be helpful when you hear instruments in silent parts of vocals, and sometimes also using denoiser might help for it (although both can make your results slightly muddier)
13. Chain separation
For vocal residues in instrumental, you can experimentally separate it with e.g. Kim vocal (or inst 3) model first and then with instrumental model. You might want to perform additional steps to clean up the vocal from instrumental residues first, and invert it manually to get cleaner instrumental to separate with instrumental model to get rid of vocal residues. Tutorial
14. To not clean silences from instrumental residues in the vocal stem manually, you can use a noise gate in even Audacity. Video
In some cases, using noise reduction tool and picking noise profile might be necessary. Video
15. Choice of good models for ensemble
Use only instrumental models for ensemble if you have some vocal residues (and possibly vice versa - use only vocal models for ensemble for vocals to get less instrumental residues) - mainly used in times when there was still strong division between vocal and instrumental models (before MDX23C release). Now it can narrow down to picking only models which doesn’t have bleeding - listening all the separate models results carefully, and pick the best 2-5 results to make an ensemble.
16. Choice of models for vocals with vocoder
(although lots of newer models were released since then)
You can use 5HP Karaoke (e.g. with aggression settings raised up) or Karaoke 2 model (UVR5 or Colabs). Try out separating the result as well (outdated models).
"If you have a track with 3 different vocal layers at different parts, it's better to only isolate the parts with 'two voices at once' so to speak"
Be aware that BS-Roformer model ver. 2024.04 on MVSEP is better on vocoder than the viperx’ model.
17. Find some leaked or official instrumental for inversion
To get better vocals
If you're struggling hard getting some of the vocals:
"I used an instrumental that I don't remember where I found it (I'm assuming most likely somewhere on YouTube) and inverted it and then used MDX (KAR v2) on x-minus and then RX 10 after.
I Just tried the one-off Bandcamp and funnily enough it didn't work with an invert as good as the remake that I used from YouTube, but I don't remember which remake it was I downloaded because it was a while ago"
18. Fix for ~"ah ha hah ah" vocal residues
Try out some L/R inverting, try out to separate multiple times to get rid of some vocal pop-ins like this
19. Center channel extraction method
by BubbleG using Adobe Audition:
(may not work on Roformers anymore, see after point 72;
and we have better models for it since then)
"The idea is that you shift the track just enough where for example if you have a hip hop track, and the same instrumental tracks the drums will overlap again in rhythm, but they will be shifted in time so basically Center Extract will extract similar sounds. You can use that similarity to further invert/clean tracks... It works on tracks where samples are not necessarily the same, too…”
>
Step-by-step guide by Vinctekan (video)
1. You take your desired audio file
2. Open it in Audacity
3. Split Stereo to Mono
4. Click the left speaker channel (now mono), and duplicate it with Ctrl+D.
*: If the original and duplicate is not beside eachother, move it so that it's next to eachother
5: Select the original left speaker channel and it's duplicate, and click "Make Stereo Track"
6: Solo it.
7. Export it in Audacity, preferably in 44100hz since UVR doesn't output in higher frequencies. Format, and bit depth don't really matter, I prefer wav always.
8: Do the same thing for the right speaker channel.
9: Open UVR
10: Navigate to Audio Tools>Manual Ensemble.
11: Make sure to choose Min Spec (since that function is supposed to isolate the common frequencies of 2 outputs)
12: Select the 2 exported fake stereo files of both the left and right speaker channels.
13: Hit process
___
20. Q&A for the above
Q: For the right channel are you doing the same with the duplicate and moving the file next to the original or just duplicating and making that stereo?
A: Those 2 steps go hand in hand. The reason I mentioned it is because, if you try to make a Stereo Track with those 2 (the left/right channel speaker, and it's a duplicate mono]) when there is a track between them, it doesn't work. Even if you select those 2 with CTRL held down.
Take that 1 channel (left/right), Ctrl+C, Ctrl+V, now you have 2 of the exact same audio. Hold Ctrl select the 2, click "Make Stereo Track". Finally, export.
_____
21. Passing through lot of models one by one
"I usually do an ensemble to make an instrumental first, then demucs 4_ft… sometimes I do it once, then take that rendered file and pass it back through the algo a few more times, depends until it strips out artifacts."
It can be beneficial also in case of more vocal residues of MDX23 or Demucs ft model compared to current MDX models or their ensembles.
22. If you still have instrumental bleeding in vocals using voc_ft, process the result further with Kim vocal 2
23. Rearrange cleaner parts
When a verse starts, and you start having muddy drums and their pattern is consistent (e.g. some hip-hop), and you have cleaner drums from fragments before the verse starts, you can rearrange drums manually, using 4 stems model and paste that cleaner fragments throughout the track. Sometimes fade outs or intros can have clean loops without vocals, which can be rearranged without even the need of separation. Listen carefully to the track. Such moments can be even briefly in the middle of the song.
24. arigato78 method for lead vocal acapella
(uses oudated vocal model)
1) Try to make the best acapella (using mvsep.com site or using UVR GUI). I recommend the MDXB Voc FT model for this with an overlap setting set to at least 0.80 (I used 0.95 for this example). The overlap for this model at mvsep.com is set to 0.80. Speaking of the "segment size" parameter in UVR GUI - changing it from 320 to 1024 doesn't make much of a difference. It acts randomly, but we're working on a beta version of UVR GUI - remember that. (...)
I noticed all the "vocal-alike" instruments still remaining on the acapella track, but wait...
2) The second part is to process the acapella thru the mdx karaoke model (I did it using mvsep.com). I prefer the file with "vocalsaggr" in the name. It has more details than the file with "vocals" in it. The same goes to the background vocals in this case - I prefer the "instrumentalaggr" one.
One important thing - all (maybe almost) of the residue instrumental sounds were taken by mdx karaoke model to the backing vocals stem, leaving the lead vocal almost studio quality ("studio"). But - it may be helpful for all you guys trying to make good acapellas. I was just playing with all the models and parameters and I accidentally came across this. Please, let me know what you think about it. I'm gonna try this on some tracks with flutes, etc. And I realize that this method is not perfect - we get nice lead vocals, but the backing vocals are left with all that sh*tty residues.
So the track is called "Reward" by Polish singer Basia Trzetrzelewska from her 1989 album "London, Warsaw, New York".
__
25. Uneven quality of separated vocals
You can downmix your separated vocal result to mono and repeat the separation (works for e.g. BVE model on x-minus).
26. Experimental vocal debleed with AI for voice
Sometimes for instrumental residues in vocals, AIs for voice recorded with home microphone can be used (e.g. Goyo [now paid Supertone Clear], or even Krisp, RTX Voice, AMD Noise Suppression, Adobe Podcast as a last resort) it all depends on the type of vocals and how destructive the AI can get.
Sometimes SAM-Audio might work for it as well.
27. Minimize vocal residues in very loud songs by lowering input volume
For very loud tracks between -2.5 and -4 iLUFS, try to decrease volume of your track before separation. E.g. for Ripple, -3dB for loud tracks is a good choice. If your track you’re trying to separate is already quiet and around -3dB, then the step is not necessary.
Fixed in most Roformers iirc and alters separation result as well.
27b. You could try out attenuating the volume of the mixture before separation (-3/6 dB), but I can't remember whether current MSST uses normalization before anyway. UVR maybe not.
28. Brief (old) models summary
MDX-Net HQ_3 or 4 is a more aggressive model for instrumentals, with usually fewer amounts of residues vs MDX23C HQ models or sometimes even vs KaraFan or jarredou’s MDX23 Colab v2.3. HQ_3 can give muddier results vs competition, though.
The most aggressive are BS-Roformer models, but they can sound filtered and even muddier at times, but cleaner. It’s good to use them with ensemble with e.g. MDX23C model.
voc_ft is pretty universal for vocals (with residues in instrumental, but not less muddy results), while people also liked Ripple/Capcut, although they give more artefacts (use the released BS-Roformer models now for vocals instead). Consider using MDX23C HQ model(s) as well, but they tend to have more instrumental residues.
29. Cleaning up bleeding between mics in multitracks
(by SeniorPositive)
"Demucs bleed "pro" tip that I figured out now, and I didn't see mentioned, that I will probably try to use every time I hear some bleed between. (...) I was cleaning multitrack from bleed between microphones in conga track, and used demucs for separation drums/rest pair, and [the] other [stem] had some of those bongos still, very very low, but it existed, and I heard it just enough.
- So I took rest signal, boosted it +20db (NOT NORMALISE! Other value but make note how much of it you boosted, go few dbs less to 0db threshold). If you do not boost it to sensible levels, the algorithm will skip it.
- Do separation once again (this time I've done it using spectralayers one, but it's also demucs)
- lower result -20dB add this result to first separation result
[The] result [is -] better separation, fewer data in other/bleed and with proper proportions.
It looks like AI is not yet perfect with low volume information and, as seen in ripple Bas Curtiz discovery, too hot content also."
30. For clap leftovers in vocal stem
Methods suggested in debleeding
31. (paraphrase of point 17)
Use the traditional phase inversion method and then feed them to the UVR models if you have a chance of finding any official instrumental or vocal, but it doesn’t invert perfectly. This way, the models will have less noisy data to work with. But it sometimes happens that the official instrumental and the vocal version of tracks have slightly different phasing. This makes isolating vocals via phase inversion difficult, or even sometimes impossible ~Ryan_TTC
Sometimes only specific fragments of song will align, and in further parts of the track it will stop and require manual aligning. You may try to use Utagoe or possibly UVR with Aligning in Audio Tools as it shares some similar functionalities.
Why don't official stems invert?
“Very rarely will the vocal or instrumental fully invert out of the master. This is because of master bus processing and the non-linear nature of that processing. I.e. part of the master's sound is the processing reacting to the vocal and instrumental passing through the same chain.
Sidechaining and many limiters are also looking ahead to the signal. Also, some processing is non-linear so even if you set it up identically re. settings, each bounce will be slightly different in nature. Stuff like saturation/distortion. Some reverbs, limiters and transient shapers etc are not outputting the same signal / samples every time you bounce, so instrumental bounce is not the same as the master bounce in terms of phase inversion.” - Sam Hocking
32a. Muddiness in instrumentals of some BS-Roformer models
Invert (at best lossless) mixture (original song - instrumental mixed with vocals) with vocal result of separation. It might increase vocal residues outside busy mix parts.
Inverting vocals instead of mixture will result in less residues, but more artificial results in busy mix parts.
A similar trick might even increase SDR for MDX23C models irc.
How to perform inversion is explained somewhere in this doc by Bas Curtiz.
It might be unnecessary to use in UVR - it might use this trick for BS-Roformer models already, but for 2024.02 on MVSEP it was beneficial.
The trick is not necessary for the 04.2024 BS-Roformer model (it sounds worse after inverting).
Furthermore, for some muddiness in this model, you can use the premium’s feature - ensemble. The default output without intermediates should be enough (min_fft is very muddy, and max_fft very noisy). Strangely, the result from Roformer from intermediates might sound slightly better (maybe it was something random). The ensemble is kinda mimicked in jarredou’s MDX23 v2.4 Colab and to some extent it can be mimicked in UVR by using 1296+1297+MDX23 HQ ensemble (or copy of 1296 result via Manual ensemble instead, for faster processing).
Now also x-minus has a drums ensemble feature for Roformer models.
32b. Fixing muddiness for MDX-Net (on example of HQ_3 model) - inverting trick
It's less muddy when mixture is inverted and mixed with separated vocals in louder parts, but vs the instrumental stem, it's worse in silent parts with less busy mix - then it has more vocal residues than the instrumental stem.
When vocals were inverted instead of mixture, it was more muddy, but still more residues were present vs OG inst. stem, just a bit less. Can't tell how it's SDR-wise.
So you can combine various fragments for the best results.
33. Descriptions of models, pt. 2
Muddiness of instrumentals in specific archs
Beside changing min/avg/max spec for MDX ensembling (or in Colab for single models), plus aggression for VR models, or manipulating shifts and overlap for Demucs models, you need to know that some models or AIs sound usually less muddy than others. Like e.g. VR tends to have less muddiness vs MDX-Net v2 arch, but the first tends to have more vocal residues. Consider using HQ2/3/4/inst3/Kim inst for fewer residues than in VR arch or BS-Roformer.
For less muddiness than in MDX-Net, consider using MDX23 Colab 2.0/2.1 or 2.2 (more residues) or KaraFan (e.g. preset 5).
34. Muddiness of 4/+ stem results after mixdown
UVR5 supports even 64 bit output for Demucs, eventually you can use Colab or CML version for 32-bit float, but mvsep.com supports 32 bit output in MDX23 model when you choose WAV. It has better SDR vs Demucs, anyway, but sometimes more vocal residues.
Then, on MVSEP beside 4 stems, you have also instrumental - ready mixture of the three for instrumental in 32 bit provided, which is not bad, but you can go to extreme, and download e.g. Cakewalk, and 3 stems separately, and now in Cakewalk:
1) Don't use splash screen project creation tool, close it
2) Go to new
3) Pick 44100 and 64 bit
4) Make sure that double 64 bit precision is enabled in options
5) Import MDX23 3 stems (without vocals)
6) Go to file>Export
7) Pick WAV 64
Output files of 64 bit mixdown are huge, but that way you get the least amount of muddiness as possible. If only MDX23 model doesn't give you much more vocal residues vs MDX-UVR inst models or top ensemble which you wouldn't accept.
Be aware that 32-bit float vs 16 bit outputs can sound more muddy. Probably due to the fact that most sound cards/DACs don’t have native 32-bit float output support in drivers and additional downsampling must be done in-fly during playback, probably even if some drivers allow using 32-bit output in Sound settings in Control Panel for the same device (while other version might not).
Spectrum-wise, instrumentals downloaded from MVSEP vs manual mixdowns are nearly identical. The only difference in one case I saw was in an instrumental intro in the song where the site's instrumental had more high end, maybe noise, but besides, spectrum looks identical at first glance without zooming it. Still, when I performed mixdown to anything lower than 64 bit, I didn't get comparable clarity to the site's instrumental. Maybe I'd need to change some settings, e.g. change project bit depth to the same 32 bits as stems and later perform mixdown to 64 bit. Haven't tested it yet.
35. Debleeding of drums in vocals by Sam Hocking
“For drums, I usually try and do some kind of sidechained denoise using the demixed Drum stem itself as the signal to invert with. If you shape 'shape' the sidechained input using spectral tools/filters/transient tools etc, you can often null more of the drum out of the vocal. My favourite tool for this is Bitwig Spectral Split, but there's several FFT Spectral VSTs out there. The key is the tools has smoothing to extend the transients in time a bit so they null more.
Difficult to audibly hear on a video, but here's a vocal stem with a lot of residue I've exaggerated in a passage without singing. I turn on a sidechain bass, drums and other stem to phase invert them out the vocal a bit via the spectral transient split in Bitwig. I then take a spectral noiseprint in Acon Digital of what's left and that works as a mild denoiser, but only after the inversion has done its thing. Don't take the noise print until you're happy, everything else is inverting out as much as you can get it, and it's not noticeable.”
36. Manual MDX23 stems mixdown issues
It can happen that after importing three stems from MDX23 or other arch, into the same session, all combined they sound so loud that they clip on the master fader. I’d rather suggest that, in many cases it can be ignored, as after mixdown it will be fine in most cases and better than with using limiter, but it also depends on a song loudness of how much clipping even the instrumental from single model will have:
37. Q: Why sometimes separated instrumentals have clipping?
A: “Mixture doesn't clip, but instrumental is clipping.
This is because where the instrumental is clipping in positive values, the vocals are in negative values, and so vocals are lowering instrumental peak value when mixed together.
If you separate a song peaking at 0 with high loudness, the instrumental will probably clip because of this (and the more loudness, the more chances this clipping can happen, as waveform is brickwalled toward boundaries values). It's the laws of physics, as that's because of these laws that audio phase/polarity inversion works.
That's why Demucs is using the "clamp" thing, or can also lower the volume of the separated stem to avoid that clipping.
- Most of the time, lowering your input by 3dB solves that issue
- Saving your audio to float32 can be a solution, as "clipped" audio data is not lost in this case” (jarredou)
So theoretically in a 32-bit float, the volume can be decreased after separation and still nothing is lost, and clipping should be fixed.
- UVR has normalization option which turns down the output volume to avoid clipping if necessary, if you don't plan to use 32 bit float and potentially turn down the volume manually later
38. Separated audio using MDX-Net arch has noise when mixture has no audio and is silent
Use denoise standard (or denoise model) in Options>Choose Advanced Menu>Advanced MDX-Net Options>Denoise output
39. MDX23C/BS-Roformer models ringing issue
“It was reported that maybe a DC offset can amplify it. Fixing it with RX before separation was said to alleviate the issue” See the screenshot how to do it,
“Don't forget to use "mix" pasting mode” - jarredou
It serves to alleviate the issue of horizontal lines in specific frequencies across the whole track, cause most likely by bandsplitting neural network artifacts. Problem presented above.
Q: Mine is 0.047% for the DC offset, so I would just do 0.047 or 0.04
A: “0.047% is kind of a normal value, it's even a great one. No need to fix that.
I don't know at what value it could become problematic for source separation models.
On some raw instrument recordings, I have seen 20%~30% DC offset sometimes, which can become a real issue for mixing then, as it's reducing headroom” - jarredou
40. Ensemble of pitch shifted results (point 4 continues)
So you follow point 4, and “change sample rate before each separation and restore it after for each, then ensemble them all”.
“on drums it was really working great, where sometimes you have sudden muffled snare because other [stem] masked it, the SRS ensemble [irc used in MDX23 2.x Colab and KaraFan] was helping a lot with that, making separation more coherent across the track.”
41. A5 method for clean separations
Consider the fake stereo trick fist from point 11, separate with BS-Roformer 1296, clean the residues in vocals manually, put the vocals back into mixture - so perform mixdown to have a mixture again, and then separate this mixture with demucs_ft (old models)
42. Using surround versions of songs
Sometimes you can get vocals separated easier from the center channel from the surround version of the song. Perhaps you might also get different separations of instrumentals from such versions, also with possibility of manipulating the volume of specific tracks before mixdown to 2.0/stereo file. It might be necessary anyway, because otherwise you might run into some errors on an attempt of separation of 5.1 file or with more channels.
Use Dolby Atmos/360 Reality Audio/5.1 version of the song
Multichannel mixes can give better results for separation. For more on Atmos read.
Be aware that the center may contain not only vocal, but also some effects.
Consider separating every channel separately, or one pair of channels at the time (rear, front, center, sides separately) or only separate center channel separately and all the rest separately.
Visit this section for more information.
43. Matchering as substitute of ensemble (UVR>Audio Tools)
If the result of some separation is too noisy, but it preserved the mood and clarity of the instrumental much better than some cleaner, but muddy result, you can use that noisy result
as the reference for more muddy target file. E.g. voc_ft used as reference for GSEP 2 stem instrumental output.
44. Retry separation 2–3 times
At least for MDX23C models it happened for someone, that every separation made in UVR differed in terms of muddiness and residues, and someone received satisfactory result after the second or third attempt of separating the same song. Consider turning on Test mode in UVR, so the few digits number will be added to the output file name, so the results won’t be overwritten during the process, and you’ll be able to listen and compare them.
45. Ensemble instrumental result with drums with max/max
Can help to fix muddiness of vocal BS-Roformer models, but drums can sound too loud in the end. Consider decreasing their volume before ensemble if necessary.
Drums can be obtained from e.g. demucs_ft (and mixture as input or from some less muddy model) or from MDX23 Colab/MVSEP (which already uses its own input from model ensemble for 4 stems)
46. Use EQ on your song before separation (e.g. for too weak “s” sounds in separated vocals)
It’s an old method used in times when models didn’t give good quality yet, might no longer be necessary after release of Roformers (e.g. Vinctekan claims it doesn't even do anything anymore). Theoretically you could use EQ on a mixture to stress vocals in the mix more, so the separation might turn out to be better.
47. Bas Curtiz video tutorial for tips and tricks and document
48. Aufr33’s demudder (more for Roformers than HQ 4)
49. Volume compensation fine-tuning for MDX-Net models
It can slightly enhance the result, helping fight muddiness a bit.
It’s no longer beneficial for MDX23C and Roformer models.
Volume compensation generally differs for every song. E.g. for HQ_3 model, sometimes 1.035 can be the best, but sometimes 1.022. By default, it affects only vocals, but when you switch primary stem in model settings, so vocals are labelled as instrumentals and vice versa (so how MDX kae Colab works), it can be used also to fine tune instrumental stems.
50. Picking correct models for ensemble (by dca100fb8)
Uses outdated models.
“I'm seeing a certain pattern, if the Mel-Roformer model from x minus leaves faint vocals in the background during silent parts of the song, then it means MDX23 & Demucs 4 htdemucs_ft models should not be used for ensemble because vocals can be heard in the background too using these models, while MDXv2 models will not leave those vocals. So it's either UVR Mel/BS-Roformer 1296 + 1297 + MDXv2 or MDX23 + Demucs + Mel-Roformer X Minus + BS-Roformer 1296 + 1297.
I excluded VitLarge because it always leaves faint vocals”
51. Ensemble only extra higher frequencies
from e.g. HQ 3 model with narrowband inst 3 model - guide
52. Use some BV/Karaoke model first, to potentially get cleaner instrumental with dedicated model afterwards
53. Set vocals to center with stereo plugin (guide by Musicalman)
Trick [working] with the [now outdated] BS-Roformer karaoke model, though it may work on other karaoke models too (I suspect you might have some mileage with MDX for instance). Anyway, the trick has to do with separating one voice from other sounds. If the voice you want to separate is panned centrally, you're already in luck; the model should expertly separate it. If not, you can rotate the stereo field so that the voice is as close to the center as possible (I use the Reaper js stereo field manipulator plug in for this). Process the rotated sound with the karaoke model and the voice you're looking for will magically be separated, even from other voices! If you need the original stereo image back, simply perform the opposite rotation.
54. Method for cleaner vocals (by YAZKEN*)
“Basically you do 2 vocal extractions, invert the polarity of one of them and render it, after that you invert the rendered audio and choose one of the extractions you’ve made and listen [to] what is cleaner” sounds familiar to what TTA actually does.
55. Spectral editing in Audacity explained (by CC Karaoke)
I typically use Audacity... But [...] RX11 has some nice shiny toys, so maybe try that. I do things the hard way.
Here's a great basic example when using the (Roformer) Karaoke model. It can really sometimes struggle with the hard consonants.
So for best results, you'll often need to isolate those in the main vocal stem by muting out all the surrounding sound, and then mixing them back in with the backing vocal stem. Of course by doing this the hard consonants will often be too loud, so you can de-amp the volume on them and then play back till you get a level that sounds like it blends properly.
Slightly more complex example; Where the vocal lines are overlapping. I tried drawing green over one of the lines to show the difference. Might be a couple mistakes lol, as I haven't checked, but you get the idea. The previous sound is a carrying note, whereas the next line is a 'HA' kinda hard hit punching words, so it has a different shape to it. This kind of more obvious difference is easier than say... reverb…
jarredou’s hint: That's a case where I would go SpectraLayers as while the 2 vocals are not on the same pitch, you can separate them manually (with harmonic selection tool). At least for that small part shown here.
In SpectraLayers, you can change FFT resolution, higher value will give you more defined freq "picture", and it can help when 2 parts are really close in pitch, like here.
The downside is that with high FFT values, you lose time resolution. So to use SpectraLayers manual selection efficiently, you often need to switch that FFT resolution value depending on the elements you are targeting, like you would zoom/dezoom in photoshop while editing a picture.
56. Sequential stem separation (by dynamic64/isling)
With single stem models, feel free to experiment with sequential stem separation -
Instrumental model first, then drums or bass, piano or guitar, strings or horns. It depends on the song whether better results will give e.g. drums or bass when separated first, the same to piano vs guitar and strings vs horns first.
57. Advanced chain processing chart (image)
It’s a method utilizing old models, and e.g. Kim Vocals 2 can be potentially replaced by unwa’s BS/Mel-Roformer models in beta UVR (or other good method for vocals) or ensembles mentioned in this document. Check the best current methods for vocals in one stem to find what works the best for your song to get all vocals before splitting to other stems using this diagram.
htdemucs v4 above can be replaced by htdemucs_ft, as it's the fine-tuned version of the model (or MDX23 Colab). Even better, you can use some of the methods for 4 stems in this GDoc (like drums on x-minus).
De-echo and reverb models can be potentially replaced by some better paid plugins like:
DeVerberate by Acon Digital, Accentize DeRoom Pro (more in the de-reverb section).
UVR Denoise can be potentially replaced by less aggressive Aufr33 model on x-minus.pro (used when aggressiveness is set to minimum), and there’s also newer Mel-Roformer (read de-reverb section).
As for Karaoke models, there's e.g. a Mel-Roformer model on x-minus.pro for premium users or MVSEP/jarredeou inference Colab.
"If the vocals don't contain harmonies, this model (Mel) is better. In other cases, it is better to use the MDX+UVR Chain ensemble for now.". It is possible to recreate to some extent this approach while not using BVE v2 models, by processing the output of main vocal model by one of Karaoke/BVE models in UVR (possibly VR model as the latter) using Settings>Additional Settings>Vocal Splitter Options, so it separates using one model, then it uses the result as input for the next model (see the Karaoke section).
MedleyVox (not available in UVR) will be useful in the end in cases when everything else fails after you obtain all vocals in one stem, as it's very narrowband. But you can use AudioSR on it afterwards.
58. See here for more on cleaning/debleeding
59. Reverse polarity and/or remove DC offset of the input file
60. Find fragments of instrumentals in your song and overlap them inverted across the whole song before separation (heauxdontlast)
60. Method for better quality of instrumental leaks on YT by theamogusguy
“I did something really odd. (...) since you can only rip max 128 kbps I did something really odd to get a higher quality instrumental:
I inverted the 128 kbps AAC YouTube rip into the original to get the acapella
I took the subtracted acapella and ran it through AI (Mel-Roformer 2024.10) to reduce the compression artifacts
I then inverted the isolated acapella and mixed it with the lossless to get an... unusual lossless instrumental file?
Also, the OPUS stream goes up to 20 kHz, but I feel like the sample rate difference is going to cause issues, so I ended up ripping AAC (OPUS is 48 kHz while most music is 44.1 kHz)”
See also get better quality from YouTube
61. Join the best fragments from various models
E.g. unwa inst models might be noisy at times, so you might want to use specific fragments of v1e/v1/v2 fitting across the song, or e.g. beta 4 vocal model in certain fragments where it’s not enough, though it is more muddy, but less noisy than unwa’s inst models. In some cases, if it’s still not enough, you might want to use BS-Roformer models like unwa’s Large or e.g. 24.10 on MVSEP. Just find which model on the list in this document has the least amounts of residues and experiment with the rest starting from models listed at the top.
62. Lowpassing lossless file to 20kHz
Sometimes it’s a bit useful in getting rid of some constant faint noise/residues from vocals in instrumentals. It might muffle some unwanted parts of the instrumental, but some more difficult fragments with more residues than usual might sound better that way. Tested on FLAC 16 compressed to mp3 320 kbps, but it should work better with lowpassing using EQ instead of compressing. Other example values you might want to try out using are 19 kHz (mp3 VBR V0 cutoff)/17.7 kHz (cutoff of some narrowband models)/16kHz (cutoff of mp3 and AAC 128 kbps)/14.7 kHz (D1581 model cutoff).
A possible explanation of why it might sometimes work is: sometimes, e.g. more oldschool hip-hop beats might have less higher tones, or even none above 16 kHz, so most of the information in this area might come from vocals in a mixture. You can recognize it especially if vocals lose much more clarity than beat in the mixture once you compress it to e.g. mp3 VBR V0 (19kHz cutoff) or lower.
63. Refrain from excessively stacking models (e.g. for RVC)
“Inst Voc, Kim Vocals, Denoise, ensemble mode, and so forth can introduce noises to your dataset as it rips away frequencies from your audio. This harms the model's fidelity and quality.” more
64. Get cleaner vocals with vocal and instrumental model mixdown (e.g. of Mel becruily models) by Havoc/mrmason347
Separate with becruily Mel Vocal model and its instrumental model variant, then get vocals from the vocal model, and instrumental from instrumental model, import both stems for the DAW of your choice (can be Audacity) so you’ll get a file sounding like original file, then export - perform a mixdown of both stems, then separate it with vocal model
65. Less vocal bleed with dim_t 256 or corresponding chunk_size (cypha_sarin)
Small difference observed on 6GB NVIDIA GPU and Gabox instv5 model where “one little vocal glitching sound from the song that only gets picked up when the segment size is lower [256]”
66. If you set 24-bit output in UVR>Options>Additional settings (or ev. 64-bit) for e.g. demudder, the results might be slightly less muddy
67. Clean loop of the instrumental used for Matechering and full separation
You can use a well sounding fragment of single instrumental model separation with high fullness metric as a reference for Matchering in UVR for phase-fixed muddy result set as target. It will have less bleeding than models with low bleedless metric, but still fuller than phase-fixed results.
You can even use fade-in and/or fade/out to reconstruct full loops of instrumental. It can be done by normalizing fading out peak with everything later, and again, and again. So you start normalizing from most of the peaks starting to fade out (so already below a certain normalizing threshold, e.g. 0dB). Then correct volume of specific fragments to avoid any pumping or sudden changes of volume across the loop.
68. chunk_size 112455 and overlap 50
To have the best SDR for Roformers, use chunks not lower than 11s, which is training chunks value of some models (rarely higher). Although, at times people get better results with 2,55s chunks (called chunk_size 112455 since UVR Roformer patch #3). But be aware that e.g. using becruily Karaoke model, using a low 2,55s chunk will lead to crossbleeding. dim_t to chunk_size conversion is later here. Sometimes even go to extremes and use e.g. overlap 50 claiming that it was better with 112455 and becruily inst model (thx gustownis). Generally every model might have a different chunk_size value at which the SDR is the highest, but maybe not the best for specific bleedless/fullness metric.
69. If you want smoother vocals from e.g. Beta 5e
Use negative values of Shift Pitch Conversion in UVR Advanced MDX-Net settings (explained more thoroughly above).
“Tried it on a regular model (bigBeta5e) - the spectrogram looks a little more cut off at the high end than without the pitch adjust and overall the vocal sounds a little rounder and not quite as harsh (so the transients are not so nuclear)” - cristouk
70. Fixing missing sound after separation of multistem models
With certain at least 4 stem models, you might find out that the inversion of a mixdown of those 4 stems vs original mixture is different. So you might get an additional 5th stem that way - your own “other”. It might be useful if some instruments got missed, or simply for remastering purposes where not having any missed bits of audio is critical for your work.
71. Start separation in a different place of the song
Cut it manually. The result might resemble changing chunks setting a bit.
72. Use instrumental model result as pre-processor for vocal model
It’s one of suggested RVC workflows
73. Don't use 96kHz and higher audio files in UVR for separation
For some reason it yields bad results and clipping. 48kHz are allright.
As a workaround, you could use: https://github.com/rorgoroth/mingw-cmake-env/releases/tag/latest ffmpeg -i "C:\input96or48.wav" -af asf2sf=dblp,ardftsrc=44100:quality=61656210:bandwidth=0.9941249 -c:a pcm_f32le C:\output44.wav
It will give you a 32-bit float file after downsampling, so you could turn down the volume before separation (probably you could even settle on some volume attenuation in the command itself). Ardftsrc with these parameters was #1 on the resamplers chart on hydrogenaudio at the time. It requires 24GB of RAM to process faster (if you have, turn on two SSDs for pagefile if you have 16GB RAM or less). Be aware that the script doesn't track the progress, you need to just wait after executing tipo it finishes. In a limited RAM scenario, it can take even 10 minutes or more for a 5-minute song. Ardftsrc can be also used in the latest Foobar2000 versions.
74. Pre-process your loud song/mixture with de-limiter
To get less distortion in vocals after separation with model
75. Try out using MSST instead of UVR
We had at least one report with BS single stem phantom center that UVR gave more bleeding despite using the same settings. You might try out Colabs as well (they're based on older MSST code before refactoring).
76. Taming top end artefacts
At least some Roformers tend to have some top-end buildup noticeable on the spectrum, which you could just lowpassed in EQ like TDR Nova. Although it might be not noticeable, it might be useful in further post-processing.
77. Models not picking anything
Esp. if you try to isolate low-quality songs, or with some elements buried in the mix, models might struggle with some instruments or also vocals.
Then you could pre-master the file in a way the drums will be more noticeable in the mix, so the model might pick it easier. In some cases, you could use upscalers like Apollo Universal or AudioSR or UniverSR with properly adjusted cutoff:
More - Tips & Tricks by Bas Curtiz
—--
Vinctekan write-up on some tips since the release of Roformers and MVSep Demucs bass fine-tune:
“- Extracting center channel for things like bass guitar now on its own produces worse results when separated with modern models like BS-Rofo, the SW variant, the finetuned Demucs Bass model on MVSEP, and the SCNet model as well. In order for this to be worth it you would have to check with something like Spectralayers to compare spectrogram of the original separation, and the separation with center channel extraction beforehand. There may be a few harmonics here or a transient there that the center channel separation did better than the original, and in order to combine these results while maximizing clarity you will have to perform a maximum spectrogram ensemble.
- Normalizing the audio to ANY DB peak does nothing now, except maybe makes the noise floor different (which is useless).
- Upward compressing/limiting/maximizing only changes the output stems dynamic, not the quality.
- Separation of other stems from the song beforehand is also almost completely useless, especially if it comes from the same multistem model.
- Adding static EQ does nothing, does not matter what the settings are.
- Putting the song through a spectrogram STFT mask suffers from the same fate as Center Channel Extraction, the results on average are a lot worse, and you would have to perform a max spectrogram ensemble in order to get the best of both outputs. It super rarely adds anything different/useful now (...)
You would think: "Oh, If I extract the center channel, then the model has less audio to dig through, and the desired stem (vocals or bass or whatever) is overlapping with less useless audio and therefore is more audible, cleaner sounding. Therefore separation will be better, YAY!"
But this stopped being the case for well over 2 years now…”
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