For reference, here is the method I've found to play a Stems format stem.mp4 file as a set of clips in Ableton Live (8.4.2).
(I don't think I'm going to actually play out with Live. Traktor seems to do nearly everything I want without the below rigmarole, albeit at the expense of a new controller. But just in case, and mostly for me in case I forget).
So the steps are:
- Install ffmpeg using your package manager
- Get a de-stemming script from here: http://blog.beatunes.com/2015/09/destemming-stems.html
- Use the script to extract WAV files, e.g:
destem.sh WAV stemfile.stem.mp4
This will create five WAV files: the one ending .stem.0.WAV is the full track, files .stem.1.WAV through .stem.4.WAV are (conventionally) the drum, bass, synth and vox parts.
- In Ableton, start a new Live Set
- Load the *full* clip, stemfile.stem.0.WAV. sort out the warping - in particular make sure the track is warped to the correct BPM and starts at 1.1.1. It should warp straight, unless the creators done wierd things.
- Duplicate and rename the clip for each section/cue point, e.g. intro, mid, bridge, outro or whatever. Give each clip a suitable name. Set the follow action so the end of each clip skips to the next (use Loop to find the number of beats). You'll now have a vertical column of clips, and if you start the first, the whole track will play seamlessly.
Now, you need to add the Stem parts.
- Insert four audio columns and name them so you have columns: All, Drum, Bass, Synth, Vox
- Select the clips you created and drag them into a folder (the folder where your clips are is good, probably). Say yes to the defaults. This creates a project (named "All") with just those clips, outside your live set.
- Drag the column of clips across into the Drum column.
- Do View/File Manager, click on Manage Set, then View Files, you should get just one row.
- Click the Hotswap button and select the stemfile.stem.1.WAV file. This is the crux. It changes the underlying sample audio from the full track to the drum part, while keeping warping, beat markers and cue points intact. It'll do this on *every* stemfile.stem.0.WAV instance, hence the need not to have any instances of this loaded that you don't want changed.
- Select all the clips and drag them to the same folder you put the "All Project" in. (But not into the All project itself). You'll now have a "Drum Project".
- Repeat the process for Bass, Synth and Vox, selecting stems 2, 3 and 4 respectively. This will give you projects for each part, each with all the clip sections
- Finally, drag each of the All/Drums/bass/Synth projects back into their corresponding columns. You'll now have a grid of samples. If you start the scene row with the intro, and have the faders up for all the parts and down for the All column, the track will play out as if it was the unmangled version.
- You can export the whole project by dragging to the browser (and renaming) or just saving as a live set. You can then drag it back into your actual set, ready to remix live.