Audio beat detection algorithm

[Skulpture]

I'd; say this is a good place to start, depends on your microphone too; what low frequency (kick) it can pick up, etc.

I have presumed this is for live capture of BPM using audio?

[Bill Cottman]

thanks for this. did not know about the tap to tempo actor! is there an alphabetical index of Izzy actors somewhere?? i've been playing with your idea using my laptop line-in and music from my iPod. do you know the relationship between the sound freq watcher sound power levels and the trigger level? i did a 6db boost on line-in level to get a robust sound power level. even after playing with many trigger levels, not many X's?? i even moved up the frequency range. thx.

[vanakaru]

I played with this as well. It will give you rather rough tempo/beat detection. Since it gets the re-occurence from frequency it tends to flux alot. I attached the beat to movie player position and it kind of does the beat match. Also the flux adds nice variation to the setup(so the movie does not play the same lenght always). So I like this alot. And it is very good start point. Maybe if you will get the triggers from different frequencies and calculate the average you should get closer to actual beat.

Maybe to use external hardware that outputs MIDI timing is better.

[ian]

If you're needing a little better control of the sound levels from the ipod... Have you ever tried working with soundflower? http://cycling74.com/soundflower-landing-page/

It's 'syphon' for sound. You can send  sound from the sound player output of izzy (or anything else on your machine) to soundflower, then recapture in izzy as new input. So for example you can have an audio file player playing your files, adjust the gain and/or hi/lo pass filters to select a narrow frequency, then loop back into izzy to measure with the sound level watcher or sound frequency watcher.

For anything with a beat being kept at middle c or below I've had had much better much filtering the frequency range down to a few single note ranges before running it into either the frequency watcher or just using a sound level watcher.

[Skulpture]

Yeah its never perfect and depends on the music style/type to be honest.

When I VJ it's normally for trance/electro/house music so its very 4/4 and 126-135 BPM so I have been lucky.

I know these are used a lot by VJ's too..

[http://www.redsound.com/products/](http://www.redsound.com/products/)

[Bill Cottman]

vanakaru: yeah i tinkered in this direction also and liked the results! i think this will satisfy my needs for now.

ian: thx. i've forgotten about soundflower. thx for the reminder. will consider this if i need more control.

skulpture: thx for the links. i have the RTA Lite app on my iPhone so i can see the freq spectrum i'm listening to

[Skulpture]

I have just found this too:

[http://showsync.info/index.php/tools/beattracker/](http://showsync.info/index.php/tools/beattracker/)

_"Beattracker is a standalone beat tracker module that analyzes an incoming audio signal and accurately detects the tempo and the current beat position after feeding it an initial tempo by tapping. It outputs the tempo and beat information in various formats, such as MIDI clock, OSC and MA net."_

_ _

_@_[vanderzee](http://troikatronix.com/troikatronixforum/profile/252/vanderzee)

[Bill Cottman]

thx Skulpture. I'm playing with Arduino today

[Skulpture]

And this....

[http://wavesum.net/products.html](http://wavesum.net/products.html)

[Bill Cottman]

thanks

[Skulpture]

I keep finding stuff! lol

[crystalhorizon]

I´m trying a different approach: In Cubase I made a midi track with a short bass drum, tapped to my main Wave Track. I exported a midi and an audio file of this bass drum sync track: The idea was to start both tracks (audible track and inaudible sync track) with a keyboard watcher or enter scene trigger-the sync track should change after e.g. 8 beats -counter actor, some effect of the video. So now I have no idea what actor midi, audio, audio core, etc actor to use for the sync track, that triggers the counter and shoul be not audible. Its not about live capturing the audio. Any ideas?

[crystalhorizon]

no one?

[Skulpture]

The MIDI player in Isadora; actually plays a MIDI file; it doesn't send the note out. 

This is where Ableton is perfect for Live stuff as that will and the MIDI out and play music at the same time.

I will have a think about the best solution today for you.

[crystalhorizon]

Yeah, saw your ableton tutorial. Thanx for helping.

[Skulpture]

Really what you need is something like Duration or Vezer

But these mostly deal with OSC (similar to MIDI in many ways really - in its simplest form they both send messages just via deferent methods/protocols)

Worth having a look anyway.

[Michel]

Duration is really worth a look.

Best
Michel

[Skulpture]

It is indeed. I don't think you can drag a MIDI file into Duration though.

But, saying that, I would swap the MIDI for OSC if I am totally honest. 

It may be a bit more work but the workflow is much better and reliable.

[Skulpture]

http://vezerapp.hu/blog/vezer-talks-osc/

MIDI and OSC.

**Note:** This isn't out yet - due out very soon!

[crystalhorizon]

On my windows machine, I managed to send OSC data from duration to Isadora. cool. but how to import my sync (midi or audio) file into duration? Skulpure I think you´re right, that you cant  import a midi file in duration.