
Show HN: DJ in the browser - musicnrd
https://lukeandersen.github.io/reactor
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packetslave
very, very cool but calling something music-related "Reacktor" is a really
good way to get a nastygram from Native Instruments.

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musicnrd
Good point, you can obviously see where my inspiration came from ;) I'll look
at naming it and moving it to it's own host soon.

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acconrad
As a DJ, a few requests on an amazing start:

\- sort by Key \- sort by BPM \- move the song dragging it (need to line up by
the kick) \- cue points

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musicnrd
I'm looking into bpm detection and cue points are on each player (they just
might be hidden on a small screen). Will look into key and dragging the
waveform.

Thanks for the feedback.

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aethos
Do you have any leads on bpm detection? I tried doing it in Python a while ago
for a project and the library I used was always 5-10bpm off...

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letier
There was a nice article on the beatport tech blog. I didn't manage to find it
when I searched yesterday. Basically what they suggested was applying a low
pass filter to isolate the base drums, then count the most common intervals
between peaks (basically some kind of transformation) and then reconstruct the
BPM from there by applying a range from 80-160 or similar. Hope this gives you
a rough idea.

I implemented and tested it and it worked quite well with electronic music.

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coroxout
Thanks! Was it this one?
[http://web.archive.org/web/20160304012151/http://tech.beatpo...](http://web.archive.org/web/20160304012151/http://tech.beatport.com/2014/web-
audio/beat-detection-using-web-audio/)

(no longer on the beatport site; tech.beatport doesn't seem to exist any more
and the current beatport blog starts at 2015)

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musicnrd
Yeah that's the one, I was looking at this post that uses Spotify and echonest
too [https://jmperezperez.com/bpm-detection-
javascript/](https://jmperezperez.com/bpm-detection-javascript/)

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keypusher
Doesn't seem to work in Firefox.

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Ace17
Same for me, can't get it to work :-(

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musicnrd
Oh bugger, what version of Firefox and OS are you using? I admit I only built
it with Chrome but I did test it last night on Firefox osx and it was working
ok.

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keypusher
Latest Firefox on OSX. Song from A plays but no sound ever comes from B
despite adjusting faders. I tried it in Chrome and it works great there.

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letier
Very cool! I hacked the exact same thing a while ago. Also with soundcloud
integration (and some filters and stuff). I'll take a peek at the code when i
get to my computer in the next days. Maybe there is something where i could
contribute.

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musicnrd
Awesome, keep me posted.

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letier
Just checked, your repo seems to be private. (or I'm a bit blind :))

Here is the link to what I hacked back then:
[https://github.com/letier/boombox](https://github.com/letier/boombox)

I'm planning on doing a complete rewrite, when I finally find the time. This
thing was build pretty quickly.

~~~
musicnrd
Wow, that's really cool.

Yeah, sorry the repo is private until I get it cleaned up a bit. This has been
built quite quickly as well ;)

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stockkid
I had fun with this. I found it kind of hard to mix without auto sync. Sorting
by key/BPM will be a good feature.

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ruler88
amazing work, I loved playing with it. I'm a DJ nub tho :( would be really
cool to have a very quick tooltip getting started mixing the first song kind
of thing

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musicnrd
Cheers, good point. I want to try and stay away from sync capabilities but it
would be a great idea to show how to beat match using the app. Thanks.

~~~
eyeJam
this is pretty great man! i've been playing with it for a couple hours now. my
only complaint is that it's pretty hard to time the drop since there seems to
be some lag between when i click and when the track starts playing (could just
be my computer though).

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zaptheimpaler
Is the playlist somewhere on soundcloud? I really liked it.

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imakesoft
This is very cool! I wish I would know how to be a DJ. :)

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peternicky
Link for source code?

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a1ps
Really cool, but we need the crossfader. :)

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musicnrd
It's coming soon, I just need to fix the logic for controlling the volume
faders and the crossfader together.

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swaraj
This is incredible!!

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antfarm
why is the crossfader disabled?

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musicnrd
Sorry, haven't had a chance to build it yet

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vincentriemer
[https://gist.github.com/scneptune/7498000](https://gist.github.com/scneptune/7498000)

