BPM calculation giving me guff

grapejuice's picture

Hey all,

I have been attempting to use the BPM calculator that the very clever Eskatonia built, in order to have QC read an incoming tempo from Ableton. That much I have accomplished, but for reason(s) beyond my meager comprehension it does not calculate a stead BMP despite being fed one by Ableton.

It seems to read the tempo correctly most of the time, outputting 120 (when the incoming BMP is 120 for example) about 90% but then once every 5 - 10 seconds burps out a few incorrect tempos - sometimes quite close to 120, sometimes not. This is even with a minimal patch set-up simply rendering the output of the 'beat clock' output to a string/billboard.

In all other ways I use MIDI with QC it is able to read it flawlessly (recieving note on/off or even extremely quickly modulating cc values). I am fairly confident that Ableton's tempo is not frequently burping or I'd hear it in the music/observe an effect in the timing of the other midi messages.

I assume this bug is due to QC calculating the incoming signal at uneven intervals. Is this so? How do I fix it? If not, has anyone else had a similar problem and have a fix?

All the best

Ryan

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

.lov.'s picture
Re: BPM calculation giving me guff

if you want to use Ableton's tempo in QC, use the IAC driver, and send the midi clock signal to QC.

I attached my comp which i use in CoGe, works fine for me - but not the best...

PreviewAttachmentSize
tapper.qtz6.65 KB

grapejuice's picture
Re: BPM calculation giving me guff

Hey, thanks for that, a clever patch! I do have my IAC all set up in the manner you describe and am able to use midi notes and ccs otherwise flawlessly.

It's much closer to what I'm after, but still not quite stable enough. It does seem to warble a little bit, but at least doesn't jump around like the one I mention above.

I do not need the BMP calculation to be very precise - just the output stable. I'm doing very simple things like using BMP/60x4 inputted into 'duration' of a interpolator to rotate a circle 360 once a bar. But every time the patch (yours or eskatonia's) outputs a new bmp the circle jitters.

Is there a way to smooth this out? I'm willing to sacrifice timing precision for downstream stability.

Also, never seen CoGe before - it might solve a bunch of my problems

Cheers!

R

psonice's picture
Re: BPM calculation giving me guff

Not entirely sure what you're doing, as I don't use any midi stuff at all, but I always use a simple stop watch for timing and it gives me a very stable BPM based timer (essential for doing heavily synchronised demoscene stuff..)

To do it, just trigger a stopwatch when your music starts (presumably with a midi trigger), and multiply the output time by bpm/60. I guess if you're being really fancy you could send in the BPM as a parameter of the trigger note or something :)

grapejuice's picture
Re: BPM calculation giving me guff

Your stop watch advice is a very clever but is n/a in what I am doing because my compositions are being modulated by non-linear midi data - loops and scenes in ableton that warp to the master bmp. There's no 'start' or end command, another computer is triggering the midi clips in ableton which just loop around and trigger in a semi-arbitary order.The clip that 'starts' along with the music might re-trigger again 26 bars later for example.

Also it seems like since the BPM warbles a little bit it would still cause jitters (when used in a calculation like bpm/60x4 into a duration to make 1 bar length)

Anyways, I don't want to bore you with my MIDI woes, but I would have imagined in the 4 + years QC has been around someone would have managed to feed a stable BMP into it from MIDI Clock!

A man can dream!

itsthejayj's picture
Re: BPM calculation giving me guff

Have had it working fine for 4 years on my end. MIDI clock from Ableton using IAC driver (which i think u've worked out). The midi clock its perfectly stable, i have been using it in my Just Add Music software for years.

Why exactly are trying to work out the BPM . I can help

Demo of Just Add Music in 2007 oh how things have changed

http://www.youtube.com/watch?v=gNkt-g0ICsU

http://www.youtube.com/watch?v=g-WKV0CxPf0

grapejuice's picture
Re: BPM calculation giving me guff

I am trying to work out the BMP so that my QC comps can be modulated via midi in a non-linear fashion, in fairly precise sync to a tempo coming from a music sequencer, taking advantage of the 'clip follow actions' functionality in ableton.

my set-up involves two macbooks - both running ableton. the 'music' laptop plays music sequences which are also often triggered non-linear style - they're called 'scenes' in ableton-speak. each of these scenes also a has a 'dummy clip' in it which passes a midi note message to the 'visuals' laptop which is also running ableton - slaved via midi message to the 'music' laptop so they both run at the same bmp at all times.

the note from the dummy clips on the music laptop trigger scenes in ableton on the visuals laptop which are made up of various midi clips (note messages and cc) which modulation my quartz compositions. the scenes on the visual laptop's ableton have 'follow actions' set-up which allows them to trigger other scenes perpetually in an ever changing order simply by launching the first 'scene' at the start of a song.

so for most of this i don't actually need the global bmp in quartz, cause the midi messages in ableton auto-warp to the bmp from the master ableton, and thus modulate in perfect time to music anyways - but having quartz be able to just read the tempo from ableton and keep'er steady would allow me to make some compositions which don't require a constant input of midi-messages to modulate the comps.

a simlple example of this would be a composition which takes the bmp/60x4 and feeds that into the 'duration' of an interpolation patch which goes from 0-360 in a loop and then use that to rotate a circle around. at whatever tempo the master sequencer was running at the circle would rotate full once per bar.

wow that was long winded!

so, any advice on how to get that steady steady bpm?

wayna's picture
Re: BPM calculation giving me guff

Hello!

I know it has been a while since the last reply but... just in case. The patch i made calculates the BPM from an input (in my case a keyboard, but you could plug anything on it i think).

Then i use the output to calculate a duration, which can be use for lfo or interpolation patches. I think it is near from what you want to do.

PreviewAttachmentSize
BPM Tap Tempo.qtz78.39 KB