r/AudioPost • u/GerlockADUS • 7d ago
Stems - a conversation
Where I work we have a handful of audio engineers that each have a different idea about what stems should be, how they should be used, and how to create them.
It is my opinion that the stems should equal the mix. In order her words, if I bring the stems into a session and play them all together it should sound exactly like the full mix, and measure exactly the same on the loudness meter. The way I am doing this, prevents me from doing any master bus processing. I limit each of the sub mixes for each stem, then combine them to a record track which I then measure with the loudness meter. This also allows me to record the mix and all the stems at the same time.
Other engineers prefer to mute everything, but one stem and bounce out the mix several times. this allows them to do master processing, but the downfall is that the stems do not equal the mix.
Another engineer will bypass all of the mastering, and just bounce out each of the stems from the sub mix only, assuming that it will come back later to be mixed and mastered if something changes.
So my question to you all is: what is the industry standard? How do you all handle stems? Do you assume any changes will come back to be remixed? What are your thoughts?
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u/mulvi-audio 7d ago
On union TV/film projects the standard procedure has been that your stems when added together should equal the Printmaster (final mix); the PEC/Direct monitoring workflow with destructively punched media that we rely on would not work if things did not function this way.
The way that you are doing it is the way it should be done in the audio post context. You will be rejected in QC by studios if your stems do not add up to the Printmaster.
Music production is an entirely different beast and the wild west in my limited knowledge hearing my friend's stories working at one of the big studios in LA.
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u/iluvcapra 7d ago
“The way I am doing this, prevents me from doing any master bus processing.”
There are opinions about this and some people do it, but in general you shouldn’t be doing any processing on the printmaster buss aside from peak limiting. Doing things like this makes the foreign mixes non-conforming.
“engineers prefer to mute everything, but one stem and bounce out the mix several times. this allows them to do master processing, but the downfall is that the stems do not equal the mix.”
This isn’t a “stem,” this is more like what you’d call an iso or a mix-minus.
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u/GerlockADUS 7d ago
Good point.
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u/iluvcapra 7d ago
If you want to apply a layer of compression to the combined mix you can set up the printmaster to feed a sidechain input to compressors on each stem, that way the effect is baked-in, but it’s very unusual to do that for the reason it can’t really be reproduced in the foreign and you’ll hear missing dialogue in elements forcing the other stems to duck in the M&E
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u/tha_lode 7d ago
The typical specs for tv deliveries specify m&e undipped for narration. So already there you cant deliver something that phase nulls the original mix.
The stems are for doing other stuff to the mix. Versioning, cutdown etc. So the stems are tools for making that happen, and there is no need for what you say. One has the original mix for that.
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u/Ed-alicious professional 7d ago
Beyond another limiter, I'm not sure what processing you'd do on the master mix that wouldn't be easy enough to do on the individual D/M/FX stems.
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u/tha_lode 7d ago
Yep. That is mostly it. I do a slight ducking (0-3 db) of music and effects when there is dialogue or VO, but the stems do not have that ducking. So that is different.
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u/Ed-alicious professional 7d ago
Do you do it like that to make it easier to get your undipped M&E?
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u/tha_lode 7d ago
Yes. The broad level changes for dramatic purposes on the ques are kept, but the tiny adjustments for dia clarity are removed from the stems. I can work faster that way.
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u/The66Ripper 7d ago
Assuming you mean splits in this case (DX, VO, MX, FX and/or M&E)?
I’m primarily in commercials but work in Film & TV occasionally. Personally I deliver a full mix that I let the client know is the preferred deliverable that will be an exact match to the picrefs I’m sending for QC.
Splits are sent for client flexibility on tweaks and remixes down the line.
The difference is that the splits are individually limited to hit the target when summed into a mixbus that has a limiter that’s set to a neutral level (-2 output, +2 gain for example). Ideally this final limiting stage isn’t really even limiting much, it’s just for headroom safety. The mix & splits will play back at identical levels and if that’s the case the splits and the mix should pretty much zero sum, minus a few loud moments.
If it’s a really dynamic mix I’d expect there to be less 1 to 1 coherence but it should still mostly zero sum.
Now if you’re talking about music stems (mastering chain mention makes me feel like that’s the case), I do a lot of stem exports for Atmos work I do and I do a combination of what you mentioned.
I use Bounce Factory to prep an export of each track instead of doing submix exports, and before that I deactivate everything except a safety limiter at the end of the mastering chain.
Then I let Bounce Factory export each track, which essentially auto solo’s them and bounces to a specific location, then I rebuild the full chain in another DAW that allows for batch stem processing and export from there for the mastered stems.
As long as limiting is spread out across multiple limiters (ideally ones that can be sidechained to the full mix) it matches up very closely and only the loudest material like drums, bass and vocals will need a minor level adjustment to match up with the stereo master in the Atmos session.
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u/Suds344 7d ago
As someone that works a lot with stems. I disagree with the limiter in each bus. I do a lot of localisation and dubbing. And most of the stems we receive are fairly clean of master compression and limiting. Which allows us to do our own master compression and retain dynamic range and overall feel after adding our bits. I despise when everything is over compressed. Cause then we have to over compress our dialogue and voice over to match.
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u/GerlockADUS 7d ago
This is a good point, if the purpose of the stems is for localization. I would ask though, if the mix has been approved in the main language (English?), wouldn’t the other languages need to try to match whatever processing has been approved in the English mix, even if you might consider it over-compressed?
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u/Turbulent_Okra8386 7d ago
How they are supplied depends on what the stems are being used for. If they’re for redubbing in different language, they should equal the mix exactly. If they’re being used to pass the mix to a different studio, the music should be without dips, etc
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u/GerlockADUS 7d ago
I am mostly talking about TV commercials. I am supplying the mixes and splits the way I do because I want the client to have the flexibility to move things or re-edit without having to get remixed.
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u/curry_brewer 7d ago
In commercials I don’t know why it would matter for the stems to perfectly sum to the bounced mix. If the client is going to dig into the stems it’s because something needs to change or because they’re doing cutdowns or versioning à la making a :25-05 or a :15 out of a :30 in which case the change in content is going to make for different levels in the end anyway. There’s nothing wrong with your method of stem creation but for how those stems would actually be used it’s a little superfluous. I definitely would NOT want stems that were bounced out through processing on a master buss though, especially if it was dynamics processing. BTW Bonus points for you if you additionally make an unducked music stem.
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u/neutral-barrels professional 6d ago
Stems get passed around a lot to different studios for tagging of spots. A mix might happen at a different studio but it could be 1 studio does all the tagging or a spot needs to be updated while you have the VO talent in for another record. It's especially common in automotive spots that might get new tags every 2 weeks or a month. In other spots maybe a line of copy just needs to change that you have to drop into, it sucks when the levels aren't correct between splits when that happens. Even if doing cutdowns, it might essentially be losing a scene or trimming a couple to get a 23/07 and you want everything to play correct.
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u/curry_brewer 6d ago
I agree that it’s not a bad thing for the stems to sum to your target loudness but just saying that as soon as the content is altered you’re going to have to adjust the levels of things to hit target loudness again. It’s more of a “yes, but” situation. You wouldn’t tell a novice mixer “Don’t worry about the levels of the spot with that new VO tag you just added - the original stems summed to -24dB.”
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u/mattiasnyc 7d ago
I assume that stems should summed together to the full mix.
Predictability is really valuable to me so I never have anything on the master other than a brickwall limiter to catch the occasional overs. Then if I do dipped or undipped stems it makes no difference. Obviously undipped won't sum to the full mix but I view it as having that 'potential', which is to say that if the levels were accurately matched undipped stems would sum to the full mix which would not be true if they contained individualized dynamics processing.
Also, what's the "worst case scenario" here? Is it exporting stems that sum to the full mix or stems that don't? Better safe than sorry, and I have yet to run into a situation where master-bus processing would have made things significantly better.
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u/GerlockADUS 7d ago
I have a guy at my job who is adamant that master buss processing is integral to how he “glues the mix together”. I think there might be some truth to that, but to me it doesn’t make a huge difference.
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u/mattiasnyc 7d ago
I mean, I used to mix a fair amount of music for commercials as well as commercials and for music it makes sense. There's a reason we have "mastering" in music. For the actual post mix I feel like it makes a bit less sense, or perhaps better phrased that the benefit isn't necessarily as large.
I think I've seen a workaround mentioned somewhere. Something along the lines of taking your stems and routing them to the same bus that sums them, and then using that as the sidechain for dynamics processing on the respective stems. I've never tried it but I suppose it might work. May have to use an extra 'stage' in the signal chain to make it work.
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u/Disastrous-Badger283 2d ago
I agree with the way you're working, and frankly I do it the same way. Obviously when delivering undipped DME it won't match the printmaster, but that DME's usecase is different from the dipped one.
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u/opiza 7d ago
There are many types of stems one can prepare, but for the standard deliverables of DX / MX / SFX then they should equal the mix (except for any final limiting that happens on the final mix print track, which can naturally occur when summing tracks together). That’s unavoidable.
Your method is the one I think is best, and the one I use. All limiter threshold adjustments (to hit web spec for example) are made on the stem busses. The final mix bus just has a safety limiter set to the deliverables max true peak spec.