Tap BPM elicits unexpected behavior

[Nathan Dotz]

in 1.9... tap tempo sets the pitch fader to be the speed of that track based on the detected bpm.
i was surprised by this. it seemed to me that it would override the detected BPM with whatever i was tapping in, then let me adjust the pitch or hit sync based on THAT number. on my cdjs, i tap, and it overrides the detected bpm. would the team be opposed to changing that? :)

[RJ Skerry-Ryan (rryan)]

Hi Nathan,

I agree tap is a little funky. My main question would be whether or not the tapped BPM would be stored in the library as the track's new BPM, as it would be easy to accidentally use the tap button and lose the previously entered BPM for the track.

RJ

[Nathan Dotz (sleepynate)]

Well, frequently I end up overwriting the BPM in the browser window just by clicking funny (like when trying to load a track), so I wouldn't be opposed to that, but I could understand if it only set the BPM for "at the speed the track is playing now and only for as long is the song is loaded".

It's pretty easy to tell if you tap ~173 and you're at +0.5% that you should go to your library and type in 172 (instead of the 114.3 that mixxx detects).

[jus (jus)]

Hmm, this bug report is confirmed while a very similar one is marked invalid.
https://bugs.launchpad.net/mixxx/+bug/686203

I think we should come clean what the BPM tap button in the GUI , the BPM tap shortcuts in the keyboard map and the BPM tap button in the track property dialog are really supposed to do.

Funny, nobody cared about the BPM tap shortcuts before ( which does the same like the tap button :-).

How about removing the TAP button for 1.9 final until we worked out a way to avoid confusion?
The button is not essential at all...

[Nathan Dotz (sleepynate)]

I personally knew about the tap shortcuts, as well as the actual ability to adjust the BPMs in the track properties, but never used them due to the "less than optimal" behavior. However, now that this has been added as a GUI feature, it becomes a usability issue. I bring it up now because I had thought "perhaps this behavior is different now that it's on the GUI" and assumed it would mimic the tap available in the track properties.

I'd like to try and elucidate, if I may, why "tap to pitch shit" is useless without "tap to set base bpm"
---------------------------------------
Assuming I'm in the middle of an unplanned set. I have a track on Deck B whose BPM is incorrectly/not detected and for whatever reason I cannot mix this track with my ears alone, I *NEED* that BPM to be relatively accurate. On top of that, it's maybe too late to just grab another track and line it up -- my previous track on Deck A may be ending.

I have a few options here:
1) cut the track over without really mixing
2) figure out some magic way to align the tempos instantaneously.

Now, if I had a feature where I could put my headphones on all the way so I'm just hearing my Deck B and tap along with it, then have Mixxx say "ok, your pitch fader is up by 1.12, so we're going to scale back what you tapped by that much, and set the base tempo for the track", this would let me see the tempos of my two tracks relative to one another -- which is the actual important thing that will help me get these tracks lined up in some kind of reasonably quick fashion. (it is worth noting that competing closed-source products have their "tap" features set up this way)

To achieve this currently, I'd have to:
1) set the track pitch slider to 0
2) open track properties.
3) hope i have a midi controller to hit play on deck B if i didn't already
4) tap the tempo i'm hearing
5) come back to the main window, hoping mixxx remembered the BPM I entered
6) now adjust the tempo relative to Deck A.

Essentially -- it's simply too many steps to make it a useful feature.

Only at this point, when I have relatively accurate BPMs for both tracks does tapping the BPM to change the pitch slider become useful at all, and even then I've never owned a device that changed pitch with tapping (my Denon DNS-12s change the base tempo when tapped, and analog tables don't like to be slapped with fingers repeatedly), so just moving the pitch sliders is what I'd end up doing anyways.

Hope this happy use-case helps.

[RJ Skerry-Ryan (rryan)]

I agree with you, Nathan. We should change the TAP button to match what people would expect. I'll work on this for 1.9.1

Thanks,
RJ

[RJ Skerry-Ryan (rryan)]

Changed the behavior in the 1.9.x branch so that tapping out a BPM will:

1) Adjust the BPM in the BPM widget to be the tapped BPM
2) The beats in the waveform adjust to the new tapped BPM
3) The rate of the playing deck remains unchanged
4) The tapped BPM is not stored in the database as a new BPM for the track.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/5733