Jump to content

Metronome diverges after beat-mapping


Homina

Recommended Posts

A bad timing problem cropped up in LPX a few years back, and I thought it was solved. Here it is again, as bad as ever, in version 10.6.3 running under Catalina 10.15.7. If someone has a way to avoid this happening I would greatly appreciate them sharing it.

 

I'm recreating Diana Krall's "I've Got You Under My Skin." It's an emotive performance filled with subtle meter variations. Its first 25-seconds is pure feeling between the performers in the band and an accompanying orchestra; I'm confident there was a conductor leading everyone, and there's just no way to put a meter to it. The song shapes up after the intro, but still exhibits timing variances. When I let LPX beat-mapping loose on the original song's file it doesn't do a very good job sticking with the band's tempo. This is true whether the ad lib beginning is included or not. This necessitates my creating a manual beat-track with a percussive pad, at least for the song after the 25-second introduction. I can do a passable manual job on the song after the intro.

 

When I playback the original song and the manually created beat-track, they stay in time throughout the song's playback. That's fine, but I can't use the manual beat-track to quantize any virtual instruments I add later; I have to have a beat-map. When I use exactly the same manually created beat-track to beat-map the song, upon playback the song-track and the metronome/beat-track slowly but steadily diverge. By the end of the six-minute song the metronome & manual beat track are very obviously different from the song track's tempo. This makes additional full-length tracking impossible since the metronome is not coincident with the song's tempo. The same thing happens whether or not I've locked the regions' SMPTE positions. It gets worse.

 

If you stop playback, either by actually stopping it or just instantaneously relocating the playhead with the cursor during playback, the metronome and the song's playback are instantly in-time. It doesn't matter where you restart playback, the song will be in time with the metronome. Just as before, however, it still won't stay in time. As playback proceeds the metronome and the song's meter will slowly diverge.

 

That is a nasty bug.

 

I've ZIPped some explanatory files: Two LPX screenshots that show the manual beat-track before and after it's beat-mapped, and two MP3 files, one of the song and manual beat-track playing in-time all the way through, and another of the post-beat-mapping's gradual divergence between the beat-mapped clicks and the song's audio. There are four or five restarts after 5:44 in the second audio file to demonstrate that restarting playback instantly restores in-time playback. About 45-seconds into the divergent audio I reduce the song-track's amplitude and pan the manual beat-track hard right so that it and the metronome are easier to hear.

 

If anybody's got a work-around that doesn't involve Olympic-level gymnastics I'd be most appreciative of hearing it.

Skin.zip

Link to comment
Share on other sites

Never heard the term "tempo ramp" before, and couldn't find anything using it as a search term, either on the web or in Logic's Help. Therefore, I can't answer your question. I can provide a look at the tempo information in my beat-mapped project, though. I've attached a screenshot of a representative piece of the tempo data. I didn't try to upload my project in the original post, just a couple of pictures and audio files. If you couldn't see those images, you probably won't be able to see this image, either...

01.thumb.jpg.d2620e68fef1d34438ac56afa010d5c4.jpg

Link to comment
Share on other sites

I don't determine the number of tempo points, the song does. When I initially had LPX analyze the song's transients and do the beat-mapping, it produced more tempo points than in my manual beat-track. If LPX cannot produce cohesive playback timing using the tempo points it generates, it's unlikely the problem originates in the number of tempo points. Back in 2016 Eric Cardenas identified this same bug. It just hasn't been squashed in subsequent versions of LPX.
Link to comment
Share on other sites

Never heard of Groove Track before. Looked at the online and Help resources, and am not confident it'll work given the length of the region involved. Nonetheless I'll definitely give it a try. The alternative is tons of hand-tweaking, so I hope using a Groove Track avoids beat-mapping's playback problems.
Link to comment
Share on other sites

I don't determine the number of tempo points, the song does.

I would want to emphasize that *you* should be in full control of this process at all times, not let some software have a guess and, ultimately, fail.

 

If it's a song with a) weak transients, b) syncopated notes, c) more than slight tempo fluctuations or d) meter changes, then I'd advise to do manual Beat Mapping, and before you freak out over doing manual labour, this only takes a fraction of the time you've already sunk into trying an automated approach. Here's how it works:

 

- Move the source Region so the first note of the music falls to a matching bar position. So if the first note is on 2+, make it fall on 1.2.3.1

- With that Region selcted, open Global Tracks > Beat Mapping

- Click-hold Beat Mapping and select Analyze Transients

- Starting with 1.2.3.1, connect the small, white lines of Logic's grid to the blue transients which show you where the music is going. Go from left to right through the entire Region, only adding tempo events where they are needed. You can and should do this in real time, with a click for reference, like this:

 

beatmap.gif.4b210df51a7722d21eef37fda1d799ed.gif

You can put tempo events on syncopated notes, you can add more in places where the tempo varies, you can even place events where there are no transients to detect but you know where it feels right.

 

This will result in an absolutely solid Tempo Map in maybe 10 minutes for a 5 minutes song, and with only a fraction of the tempo events than before you have good chances that your tempo-drift-problem is gone.

Link to comment
Share on other sites

"Go from left to right through the entire Region, only adding tempo events where they are needed. You can and should do this in real time, with a click for reference"

 

There are a few things to bear in mind here. One, beat-mapping worked without playback timing divergence in Logic version 9. I used it regularly. Therefore, beat-mapping with subsequent accurate playback is possible. Logic Pro X version 10.6.3 simply doesn't provide it despite claiming that it does. Two, the process you describe is precisely what I've had to do, manually, to impose more faithful timing on a song in lieu of Logic 10's flawed automatic process. Having to do it when I did not used to have to do it is irritating. That's the point: if the process LPX provides to accomplish this goal worked, no one would have to take additional actions to achieve that goal. I presume LPX's transient analysis discloses as many points as necessary to reflect the timing variations in a song. If that wasn't the case, what would be the point in having the capability? That LPX does not make accurate playback possible using its self-generated definition points IS the issue. Three, you state that tempo points should be added in real-time. I don't see that there's a practical alternative. However, the recommendation to use a click-track is nonsensical. My opening statement in the original post referred to the song's highly emotive nature, which entails many timing variations. That precludes the productive use of a click-track. For a click-track to be useful the song couldn't display timing variations in sufficient number or magnitude to be a problem.

 

People have been making music for thousands of years, most of that time without digital assistance. Computers are machines, people are not. Computer-produced music is sterile and lifeless, reflecting its origins. It approximates human music much as anime approximates human life. Variations and imperfections are what defines music that humans enjoy and want to hear. Logic is a tool, which is supposed to make producing human music easier. Most of the time it's fabulously useful in doing that. Sometimes, as in this case, it falls on its face. When a deficiency in Logic is disclosed it needs to be corrected. Users should not have to tailor their approach to music production to accommodate the shortcomings of the tools they use. That's especially true when the exact capability at issue used to be available in earlier versions of that tool. In short, Apple needs to address this timing playback deficiency in LPX; users ought not have to do anything beyond using its capabilities as advertised.

Link to comment
Share on other sites

Dude. Calm down.

 

The click you're hearing is the audible representation of Logic's grid, the one which you're twisting and bending to fit the song's flowing tempo changes. There's nothing static about it. You're molding it to the song in this very process.

 

Again, you can be done with this in 10min tops. Unless you want to go off on a tangent, that is.

Link to comment
Share on other sites

I don't determine the number of tempo points, the song does.

I don't understand this comment. Are you doing automatic beat mapping, or manual beat mapping? Oh ok, reading further I see that you are indeed trying to do automatic beat mapping.

 

I presume LPX's transient analysis discloses as many points as necessary to reflect the timing variations in a song. If that wasn't the case, what would be the point in having the capability?

No, transient analysis is the detection of transients, not timing variations or tempo points. Even if you have a steady tempo, you can have many transients detected. The point of detecting transients is to help with time stretching, time alignment, flex editing, sample mapping and/or slicing.. and a few other features.

 

In any case from what I'm reading the issue isn't with beat mapping per se, but with the transient detection? Perhaps worth trying to open your audio file in the Audio File Editor in transient editing mode and make sure you double-check and adjust the number and position of transient markers before doing your beat mapping.

Link to comment
Share on other sites

After reading this I had a go at Beat Mapping Diane Krall ' I Got You Under My Skin' - great version! I only ever do Manual Beat Mapping [ MBM] by the way..this track presents a very interesting persistent problem for MBM's. When there is clear tempo pulse to follow its easy ( see attached Project from Bar 15 Onwards).

 

The problem I always have is 'interpreting' the intros and outros particularly with orchestral tracks because unless you have the chart in front of you how do you work out where the bar lines are? It is very difficult for those not really orchestrally trained arranger types - I would be VERY interest to to know if any LPH members can HEAR where the bar lines are... in the intro. ( Ski? Jay?... )

 

Alternately one could check Diane Krall's credits, google Arranger and ask politely if he could just send us the bar count :) ...

 

Look forward to comments!

 

PS By the way there is NOTHING wrong with Logic ... it is all down to the Beat Mapper's musical knowledge and whether they understand time...

I've Got You Under My Skin -BeatMap v.21Sep21.logicx.zip

Link to comment
Share on other sites

@Fuzzfilth - Huge Respect! - I downloaded your version and your map makes complete sense of the first 8 Bars.

 

As I said this is a musical experience thing done with ears - no Logic algorhythm is ever going to achieve this. I just couldnt hear where the bar lines were.

 

So just to be clear: you did this not by putting in midi template beats but by adding transients? I guess it could be done both ways...

08.17am Actually I just read your earlier post #8 where you explain it very clearly!

 

Also one other thing - I have tried using Logic's Smart Tempo to Beatmap pieces of music that have a very regular pulse and it does a pretty good job but in my experience the resulting Project does not lend itself to making accurate charts. I have found the only way to get a project accurately Beatmapped is to do it Manually.

 

But then I could be completely wrong - stuck in one's own workflow bubble there are often very basic things one misses for years...

 

PS And thanks to @Homina for bringing this marvellous track to our attention - I've learnt some vital new stuff about Logic ' It's never too late' ;)

Edited by Music Spirit
Link to comment
Share on other sites

Thanks. One could argue that bar 2 should be half tempo and thus only be half a bar, but who cares unless you print the charts and put them in front of players, and even though it might cause a raised eyebrow here or there, no one will really make a fuss about it.

 

I have tried Smart Tempo a couple of times and had mixed results. Yes, with a solid beat and rhythmically unambitious material, it gets good results with obscenely little effort. But then, if there's that break where the whole band obviously plays triplets over half a bar, ST will gladly report a hefty tempo change instead, which will also move all your following bar lines, rendering all following tempo points useless and you spend the better half of an hour trying to salvage these until you give up and re-do it by hand in five minutes.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...