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Old 09-30-2010, 08:40 PM
pfo pfo is offline
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Default Elastic Audio in Depth

***I've asked these questions in other threads, but never gotten a response from Avid. However, I feel like the tech support presence here has improved noticeably since the rebranding, so I'm going to assume my questions got lost in the undoubtedly huge volume of thread reply emails these guys must get. As such, I'm starting a new post in hopes that I actually get a response this time***

What are the different Elastic Audio algorithms really doing, and what do they like to see to produce the best results?

The Pro Tools manual really doesn't go into much detail about how EA does its analysis, or give any kind of detailed explanation of the parameters of each plugin. For example, it will tell you that you can move the analysis markers as needed, but it doesn't say where they ought to be in the first place. And telling us that we can adjust the window size isn't very helpful when there's no real explanation of what the window is, or how it affects the processing. I've done plenty of experimentation, but it's very difficult to ascertain exactly what's going on using only trial and error. A real explanation would be very helpful.

With compression, eq, reverb, etc, it's easy to say "do it til it sounds right," but with the often extremely minute phase and timing changes produced by EA processing, that's really not a reasonable response. Often, things will appear to be "right," but then later I'll notice a random transient with a phase or timing issue, which leads me to question all the others that seemed right before. If there was a clear, in-depth explanation of the algorithms and processes, I think there would be a lot less guesswork, and as an added bonus, probably less bitching about EA messing up the audio. I've been working heavily with EA, and I've gotten very good results, but I'm still not quite there and I'm tired of guessing what's working and what isn't. There are a lot of variables and parameters in Elastic Audio, and I would like to have a proper understanding of these tools and how to use them.

On to the questions:

1) I notice that analysis markers are rarely placed at the start of a transient. But then sometimes they are. Where is the true "start" of a transient, and in which part of a transient should the analysis markers sit? It's no good to have warp markers in the middle of a transient, but does the location matter as much for analysis markers? It would seem that at the very least, they should all be in the same place relative to the transients.

2) How does the "Window Size" affect the processing, beyond making it sound less crappy or more crappy? What is the window, and what is it really doing? Does the start of the window sit right on the analysis marker, or does the window extend out to either side of the marker?

3) The manual tells us that we can turn on the envelope follower, which "simulates the original acoustics of the audio being stretched." I can't imagine ever not wanting the results to sound like the original audio, but this must be optional for a reason. So practically speaking, when would you want this enabled or disabled, and why?

4) Very often, a snare hit will get a marker in the overheads, but not in the room mics. What's the proper way to approach this situation? It's not realistic to expect anybody to place them by hand in the room mics, as you really can't see the transient with any degree of precision. Additionally, until there's a clear answer for the first question, we'll never know exactly where we would need to place the marker anyway.

5) What about the situation where the snare does get a marker in both pairs of mics, but they're not in the same relative location (ie, right before the transient in the overheads, and somewhere in the middle of the transient in the room mics)? Which is correct? Does it matter?

6) DigiTechSupt mentioned in another thread that we should copy the analysis markers from one track and paste them onto other tracks. How? The manual seems to make no mention of this, and for the life of me, I can't figure out a way to do this. But it does seem like that could help with some of these issues.

7) Obviously, the offset between overhead and room mics is constant, but the EA analysis markers never are. This seems like a major source of phase issues, so what's the best way to ensure that the markers are consistently offset by the correct amount from one track to the next?

8) I've started using stereo tracks for any mics that are paired or stereo (kick in/out, snare top/bottom, overheads, etc), and it definitely seems to help with phase issues within each pair. Should I take this to the logical extreme and start using multichannel tracks? I started doing that once, but ran up against some reason why it didn't seem like the right way to go, though I can't remember now why I abandoned that line of thinking. Maybe the analysis markers meant for cymbals were showing up on the kick and snare tracks and causing problems? I don't know. I guess you could do the analysis and then drag the regions onto multichannel tracks for the warping....but is this even a good path to go down?

9) Take a look at this screenshot. You're seeing the snare top/bottom, overheads, and room mics, all on stereo tracks (I didn't record these, so I can't tell you much about mic placement or anything). When I make a very small timing adjustment to a transient that falls a few beats after this screenshot, the relationship between the snare mics and the overhead mics (highlighted area) changes by about one millisecond, which completely alters the sound of the snare when heard through the close mics and the overheads. Is this avoidable, or just part of the deal with Elastic Audio?


Thank you for your help. I know some of these phase issues can be very minor, but they really do affect the realism and depth of multitrack drums. And beyond that, it's the principle of the thing. We're told that EA preserves the phase relationship of multitrack drums, yet simple experimentation will show that this is not always the case. Well, it either does or it doesn't. And if it does, then we're clearly not using it right, so educate us! And if EA just isn't the best tool for drums that are meant to sound natural (ie, not a slammin' pop tune), just tell us, so we can stop trying to make it work. If it were any other type of process, I'd just keep twiddling with it until it sounded right, but phase relationship is a very sensitive thing and the changes made by EA can be very subtle. Precise tools require precise understanding.

I remember in the earlier days of Beat Detective, even Pro Tools geniuses often described it and its analysis process as "black magic." As a result of this lack of understanding, there are probably thousands of threads here asking how to properly use Beat Detective. I really do think that a lot of the complaining about EA stems from the fact that we're all basically in the dark about how to make the damn thing work properly. The best methods for using it that I've discovered have come either from other users, or from my own experimentation. That doesn't make sense to me. Why should we need to rely on trial and error (our own or that of others) to figure out how to use these tools? That's perfectly reasonable for creative tools like reverb and compression, but for a technical process like EA, where there is a "right" and "wrong" way to use it, the manual shouldn't leave us guessing how to use it correctly. The Pro Tools manual is helpful, but just not deep enough.

I would love to hear from anybody, especially you folks who helped to design Elastic Audio. I know you know the answers to these questions!

Many thanks!
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  #2  
Old 10-01-2010, 03:46 AM
2fly 2fly is offline
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Default Re: Elastic Audio in Depth

Hi

Very interesting set of questions that I'd like to know the answers to too......but the long and short of it is that when using EA with drums you should be moving markers etc over a set of grouped tracks this way the phase alignment stays in check. Is that how you're working or are you adjusting each instrument (kik, snare, overheads) separately??? If so that must take forever.

There are definitely issues with EA .... exposed cymbal fades can occasionally (not always) be heard chattering away with little blips, artifacts. I've had most trouble with this when pulling up sessions taken on a different PT rig....

The different algorithms are designed to work with different source material and on the whole they work well but it doesn't hurt to experiment!
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  #3  
Old 10-01-2010, 04:33 AM
midnightrambler midnightrambler is offline
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Default Re: Elastic Audio in Depth

Yeah, good luck getting answers to these. We're still waiting for Jeremy's question to be answered, so....
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Old 10-01-2010, 07:07 AM
pfo pfo is offline
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Default Re: Elastic Audio in Depth

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Originally Posted by 2fly View Post
Hi

Very interesting set of questions that I'd like to know the answers to too......but the long and short of it is that when using EA with drums you should be moving markers etc over a set of grouped tracks this way the phase alignment stays in check. Is that how you're working or are you adjusting each instrument (kik, snare, overheads) separately??? If so that must take forever.
Yeah, I guess I should have mentioned that I'm aware of and use most of the generally accepted rules and superstitions of Elastic Audio (grouped tracks, different algorithms for different tracks, ticks vs samples, etc).

But that's my point -- there shouldn't be superstitions about a tool like this. It's just lines of code, written by real people, to achieve a specific task. And yet, we're all left having to develop theories as to how to use it. It just doesn't make sense to me that the documentation can't explain it clearly and dispell the myths. It just leads to poor understanding, improper use, and the assumption that it "doesn't work."
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  #5  
Old 10-01-2010, 09:28 AM
jeremyroberts jeremyroberts is offline
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Default Re: Elastic Audio in Depth

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Originally Posted by midnightrambler View Post
Yeah, good luck getting answers to these. We're still waiting for Jeremy's question to be answered, so....
And in another thread, Tim jumped in, but never answered...

I still have no idea what it's doing. Does anyone? Thanks for linking to the old thread!
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Old 10-01-2010, 11:51 AM
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DigiTechSupt DigiTechSupt is offline
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Default Re: Elastic Audio in Depth

I'm going to answer as many of these as I can and try to get some time with the developer engineer to lay the rest out in more detail.

The reason this hasn't been answered before is simply that taking the developer off what they're working on to answer these questions presents some difficulties.

#4 - This is why grouping is important. When grouped, those analysis markers apply to all grouped tracks so, while you may not have that marker in the overheads, the markers on other tracks will 'warp' the overhead at that same marker, keeping everything phase aligned.

#5 - Same situation applies as #4

#6 - After analysis, just select the region (you may have to change back to regions view if the region is not already selected), copy, then select the region you want to apply it to, switch to analysis and paste.

#7 - Again, grouping is what keeps everything in alignment.

#8 - This sounds like another case where grouping would solve the problem.

#9 - It looks like what you need to do here is place a warp marker before and after where the actual audio starts and ends in the region, to 'bound' the audio with the marker. So you would place a marker at 4:20.655 for all those regions (before the beginning of the audio and with the marker at the exact same point on all related tracks) and another at the end, just past where the audio ends on the track. When you move a warp marker, it moves relative to the warp markers around it - if there's no 'bounding' warp marker, it's going to move everything to the right or left of the marker (assuming you're using the 'shift' key to constrain movement between the markers directly to the left and right of the marker you're moving). Again, grouping is a great way to keep things aligned - the marker on one track will warp all other tracks in the group even if the other tracks don't have a marker at the same point.

One thing I would suggest is checking out Kenny Gioia's Groove3 tutorials on EA - he knows his stuff and his tutorials are an excellent way of seeing a 'real world' example of what's going on, as opposed to reading it on a page...

(That last is not a direct endorsement by Avid - it's my personal opinion/recommendation.)
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  #7  
Old 10-01-2010, 11:54 AM
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Drew Mazurek Drew Mazurek is offline
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Default Re: Elastic Audio in Depth

IMHO, for anything other than simple 4/4 drumming, Elastic Audio is a bust!!
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  #8  
Old 10-01-2010, 11:59 AM
jeremyroberts jeremyroberts is offline
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Default Re: Elastic Audio in Depth

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Originally Posted by dmazurek View Post
IMHO, for anything other than simple 4/4 drumming, Elastic Audio is a bust!!
Drew,

I've used it on mono voices and instruments to fix a feel thing -- or if the bass player didn't hold the note long enough, or to manipulate a timing here or there. An acoustic guitar flam. Etc.

And the alternative (find the talent, perform again) was usually impossible.

My results have been surprisingly good.

But I don't use it like some to totally manufacture something that was never there in the first place.

So for some uses, EA is an amazing tool, and I'm glad it's there.

FWIW.

J
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Old 10-01-2010, 12:11 PM
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Drew Mazurek Drew Mazurek is offline
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Default Re: Elastic Audio in Depth

I hear you!! That's how I use it. But as a replacement for Beat Detective (when you have to unfortunately do that type of thing) it's a bust IMO. Again, unless the part is super simple and even then you sometimes get artifacts.
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Old 10-01-2010, 03:15 PM
pfo pfo is offline
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Default Re: Elastic Audio in Depth

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Originally Posted by DigiTechSupt View Post
I'm going to answer as many of these as I can and try to get some time with the developer engineer to lay the rest out in more detail.

The reason this hasn't been answered before is simply that taking the developer off what they're working on to answer these questions presents some difficulties.
Totally understandable, thanks for taking the time to chime in.

Quote:
#4 - This is why grouping is important. When grouped, those analysis markers apply to all grouped tracks so, while you may not have that marker in the overheads, the markers on other tracks will 'warp' the overhead at that same marker, keeping everything phase aligned.

#5 - Same situation applies as #4
The thing is, my drum tracks are always grouped. I would never perform an edit on any multi-mic instrument without them grouped. And with regard to #5, if you have an analysis marker at the start of a transient in the overheads, and somewhere in the middle of the transient on the room mics, even if they do both apply to all tracks, wouldn't that cause odd results when you warp? I mean, that essentially means the same transient is represented in multiple locations in each track. And for that matter, close mics vs overheads, the markers will always be in different locations. I always assumed the point of the markers was to say "here's transient x in the snare track, and here's where transient x is represented in the overhead track." It seems odd to apply both markers to each track. But then maybe I'm not fully understanding analysis markers.

But here's the other thing. When I started pairing my paired and stereo mics onto stereo tracks, 90% of my phase issues disappeared. With overheads on mono tracks, I'd often get an analysis marker showing up on the left channel but not the right, or have them showing up in slightly different locations, and every time that happened, there would be weird swishing across the stereo field. That suggests that the markers don't actually apply to every track, as it certainly sounded like each channel was being warped slightly differently. Putting them together on stereo tracks forces EA to treat them as one track and choose one spot for the analysis marker, and now my only phase issues are from one set of mics to the next, not within a pair. That's why I was experimenting with using quad or 5.1 tracks for the drums.

Quote:
#6 - After analysis, just select the region (you may have to change back to regions view if the region is not already selected), copy, then select the region you want to apply it to, switch to analysis and paste.
Thank you! I hadn't tried selecting the region in waveform view, only clicking on it in analysis view and pressing apple+a, thinking it would select all markers, but it would never let me copy them. I'll give this a shot tonight. So is that a good way to work -- analyzing key tracks like kick and snare, and then simply pasting those markers on the other tracks? Seems like, while helpful, it might not be the ultimate solution.

Quote:
#9 - It looks like what you need to do here is place a warp marker before and after where the actual audio starts and ends in the region, to 'bound' the audio with the marker. So you would place a marker at 4:20.655 for all those regions (before the beginning of the audio and with the marker at the exact same point on all related tracks) and another at the end, just past where the audio ends on the track. When you move a warp marker, it moves relative to the warp markers around it - if there's no 'bounding' warp marker, it's going to move everything to the right or left of the marker (assuming you're using the 'shift' key to constrain movement between the markers directly to the left and right of the marker you're moving). Again, grouping is a great way to keep things aligned - the marker on one track will warp all other tracks in the group even if the other tracks don't have a marker at the same point.
Right, I understand bounding the warp with extra warp markers. But what you can't see is that this is one of several edits throughout the track, so there are warp markers before and after this edit. I understand that warping a given spot will naturally cause everything between the warp markers to shift slightly, but that's one of the main reasons I'd like to use EA instead of Beat Detective. I want the timing to shift gradually in a natural way, I just want them to remain phase coherent. But if the offset between the close mic snare and the overhead snare changes, then there's no way their phase relationship could stay the same. This may just be a limitation of EA, but I'm hoping it has something to do with the window size, decay time, or some other parameter I don't fully understand.

Quote:
One thing I would suggest is checking out Kenny Gioia's Groove3 tutorials on EA - he knows his stuff and his tutorials are an excellent way of seeing a 'real world' example of what's going on, as opposed to reading it on a page...
I've seen those, both the PT7 and PT8 versions, and he certainly has some helpful tips. However (and this is not meant in any way to take away from Kenny's work or talents), I really didn't feel like the results sounded natural. Granted, listening through the video is maybe not the same as hearing it in the room, but I think I remember hearing all the usual phase artifacts and stuff, and assuming he was going to address it at some point, but he never did. Or maybe I missed that section? Even so, for the work he was doing in the video, a loud pop/rock track where the drums really aren't necessarily even expected to sound super natural and organic, that's probably not as much of an issue, so it really could come down to the style of music.



To me, the best reason to use EA instead of BD is to avoid over-quantizing. I really love how I can change just a few errant hits here and there, and everything leading up to and away from that spot will adjust gradually over time until the next warp marker. And it's extremely simple to experiment with warping different hits to achieve the most natural result. It really is an amazing tool, and I'd like to believe that with a full understanding of the plugin parameters, it can work on multitrack drums.

Any insights on question #1? That actually applies to much more than EA -- Beat Detective, tab to transient, etc. Is it a problem that EA constantly places analysis markers in the middle of transients? Obviously, placing a warp marker in that location is a bad idea, but what effect does the exact location of the analysis markers have? Is it even important? Are they like Beat Detective event markers, in that they determine the precise spot that will get cut (or warped, in this case), or are they just meant to mark the general location of the transient, and we're supposed to adjust the plugin parameters to fit?

Thank you for your help, I really appreciate you guys taking the time to clear some of this stuff up. Like I said, I think EA is an amazing tool with a lot of potential, I'm just certain many of us don't fully understand how to realize it's full potential.
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