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Re: How to write a sequencer?

From: Peter van der Noord <peterdunord@gmail.com>
Date: Mon, 6 Aug 2012 21:28:12 +0200
Message-ID: <CAL9tNz9NoNGghjpgBuGQdAxFSie_TfrFZvBONS6i3gsear29NA@mail.gmail.com>
To: Chris Rogers <crogers@google.com>
Cc: "public-audio@w3.org" <public-audio@w3.org>
I'm not sure your example is what i am looking; i need something that
outputs that sequence as a signal (in patchwork, i use 0.2 "Volt" per
octave, so the lowest frequency would be a signal of -1, and the highest,
10 octaves higher, at 1), so i can control other things with it (my
notesequencer doens't directly control other modules itself, other modules
are controlled because they interpret that signal).

But i guess that should be done in the same manner as a triggersequencer
(have a module that outputs a continous signal of 1, connect it to a
gain-control, and set the gain-control accordingly)



2012/8/6 Chris Rogers <crogers@google.com>

> On Mon, Aug 6, 2012 at 8:51 AM, Peter van der Noord <peterdunord@gmail.com
> > wrote:
>> In the light of all the discussion about the limitations of the jsnode(at
>> least for writing audio) i was curious about any ideas how i should write
>> myself a sequencer using the native nodes.
>> I need both a notesequencer (sends out frequencies mapped to the -1,1
>> scale) and a triggersequencer (that can send out a single value of 1). I
>> thought about having a jsnode scheduling a gainnode which has a
>> buffersourceconnected to it that's playing a looped buffer containing just
>> one value (a 1).
> Hi Peter, I've actually done something like this although it's very much
> unfinished and was written before we had an Oscillator  node.  Please don't
> use it as a definitive guide, and I know there are bugs there, but still it
> might give you some information:
> http://chromium.googlecode.com/svn/trunk/samples/audio/wavetable-synth.html
> I have a simple UI for it, but others could be written letting you draw
> custom curves, etc.
> For a monophonic subtractive synth you can create a single Oscillator
> node, turn it on (with noteOn()) and just let it run forever, add an
> AudioGainNode for the amplitude envelope, add a BiquadFilterNode (or two or
> three...) for the filter.  You can control the monophonic note events by
> "gating" the amplitude and filter parameters appropriately (something like
> my example above).
> Hope that helps,
> Chris
>> - are there better ways to do this?
>> - i read about the dezippering of the gainnode. It's unspecified, but i
>> assume it filters out fast changes. Woulnd't it be a good idea to be able
>> to turn that off? If you want to do AM with it, you're not really looking
>> for a node that interferes with your controlsignal.
>> Peter
Received on Monday, 6 August 2012 19:28:40 UTC

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