a question of creative stems recomposition

[Krakatau]

Hi all

I'm a begginner on that specific task of unmixing and creating stems but I progressively realize how much this technique can be a fantastic creative tool

Of course, I assume the technique is still on a process in progress, that many improvements have still to come, but in its actual state it is already a world of creation to discover

for instance I bought a few days ago Spectralayers Pro with a special crossgrade price (coming from Isotope RX it costs me 125 Swiss Francs including taxes) ...in that software I just scratches the surface, having a glance on how separate stems can be refined and polished by internal effects

...also realize that the quality of the stems aren't to be blamed when internal non-linear effects where involved in the original mix (like compressor as I noticed)... so the might be studies to see how to compensate these flaws effectively ...if reasonably possible !

the peculiar case I'm targeting yet would be the substitution/integration of a drum and bass part of the intro of "perpetual change" from "the yes album" in substitution of the ones of the Coda parts at the end of "singing in the shower" from "Sparks & Rita Mitsuko"

... I see immediately two obvious challenge to reach that task

1) time stretch operation to match one tempo to the other
1) a polyphonic (but not necessarily in the peculiar case) pitch correction of the bass part to match the harmony of the targeted composition

...hoping it would not distorted the original song too much, ...or eventually involve a pitch to midi control to pilot another sound (especially in the case of a monophonic, that is more or less the case with the Chris Squire's bass line of the intro,
...that is at least of course, much more recommended to avoid copyright restrictions

Currently, I owned and might involved the following softwares and plugins

01) Spectralayers Pro
02) Isotope RX 10
03) Celemony Melodyne
04) RipX Daw Pro
05) Ircam Lab TS2
06) DSP-Quattro 5
07) Rogue Amoeba Audio Hijack Pro
08) Zynaptiq Pitchmap
09) Metasynth CTX 1.4
10) Imitone

...and many other occasionally

So the question is, if you were me, how would you proceed and in witch order ?

_____

EDITED : I forgot to mention Logic Pro 11 as host in where all Frankenstein-like manipulations will be recomposed together (...litterally !)

[Krakatau]

On my early experimentation I was thinking one one point : what would be appropriate effects or calibration of usual effects (eq, compressors, etc..,) to work at the best with stems, smoothing or reducing unavoidable artifacts on a renewed mix and master ?

[Krakatau]

also, are current pitch and harmony analyser accurate enough to grab the scales and chord progression out of a stems of a single polyphonic instrument ? (guitar, piano, synth, etc...) ...or even out of an "other" type of stems ?

[gullfo]

for re-mixing? i MIDI everything and then replace the instruments. maybe keep the vocals or solos if needed/desired. vocaloid the vox, new instruments on solos - replace guitars with moog, replace moog with flute, etc etc. not limiting myself to the original instruments.

[Krakatau]

for re-mixing? i MIDI everything and then replace the instruments. maybe keep the vocals or solos if needed/desired. vocaloid the vox, new instruments on solos - replace guitars with moog, replace moog with flute, etc etc. not limiting myself to the original instruments.

that for sure one option,...what ideal tools for pitch-to-MIDI in the case ?

[metalifuxx]

Ableton Live has three builtin modes that does Lead (mono), Chord (poly) and Drums. A quick simple right click on the audio track and it creates a new midi track right below.

Jam Origin Midi Guitar/Bass plugins, can be used in real time with not much latency. Can do mono and poly with chords and has some options/sensitivity/thresholds for how it detects notes/chords/scale and what kind of midi chord to make as in formation of an open guitar chord/power/bar, full range piano, chord or mono/lead.

I have no reference or comparison to quality between them though.