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Re: Web Audio API ambient drone

From: lonce wyse <lonce.wyse@zwhome.org>
Date: Tue, 17 Jul 2012 13:53:29 +0800
Message-ID: <5004FDD9.7070309@zwhome.org>
To: public-audio@w3.org


     I don't think anything is broken.
     If you listen to his drone (with non-looping noise) you can hear a 
slow evolution of timbre. This is due to the subtle differences in 
frequency content being generated by the different noise sources over 
time, combined with his extremely narrow filters on each source.
     If you can hear the slow variation in time given his original 
algorithm, then it is clear that using 2-second looping noise sources 
(assuming they all had the same loop durations) would create an audible 
2-second repeating pattern.
     No need to fix anything!

- lonce
Lonce Wyse, Associate Professor
Communications and New Media
Director, IDMI Arts and Creativity Lab
National University of Singapore
www.anclab.org <http://anclap.org>

On 17/7/2012 12:49 AM, Chris Wilson wrote:
> Hmm.  If there is a perceptible looping effect, that's broken and 
> should be fixed.  (I used looped noise in the web audio vocoder 
> (webaudiovocoder.appspot.com <http://webaudiovocoder.appspot.com>, 
> needs Chrome Dev channel or better), and never noticed a problem.)  If 
> you happen to run across it again, could you forward me a repro case?
> -C
> On Sun, Jul 15, 2012 at 1:06 PM, Matt Diamond <mdiamond@jhu.edu 
> <mailto:mdiamond@jhu.edu>> wrote:
>     Thanks for the tip! An earlier version of this did in fact use
>     pre-computed noise buffers, but I felt there was a vaguely
>     perceptible "looping" effect because of the looping noise sample
>     (it was a cool effect though). Another reason was that I was
>     presenting a version of this script at a meetup, and felt like
>     utilizing a JavaScriptAudioNode for real-time noise generation
>     would be more interesting to demonstrate... but yes, it certainly
>     takes a bit of a toll, and running a bunch of AudioBufferSource
>     nodes would probably be much less taxing.
>     Still, I'm pretty impressed that the API is able to handle so
>     much, even if it's only on higher-end machines (I'm running it on
>     a year-old MacBook Pro).
>     Matt
>     On Sun, Jul 15, 2012 at 8:03 AM, Chris Wilson <cwilso@google.com
>     <mailto:cwilso@google.com>> wrote:
>         Hey Matt-
>         Neat!  I like the apparent pitch generated by bandpass filter.
>         One comment - instead of continually generating noise via
>         JavaScriptAudioNodes, you'd probably find it much more
>         performant to pre-generate a couple of seconds (to avoid any
>         detectable periodicity) of noise in a Buffer and playing it as
>         an AudioNode.  That would probably be a bit more performant
>         than continually calling Math.random for each sample.
>         var lengthInSamples =  2 * audioContext.sampleRate;
>         var noiseBuffer = audioContext.createBuffer(1,
>         lengthInSamples, audioContext.sampleRate);
>         var bufferData = noiseBuffer.getChannelData(0);
>         for (var i = 0; i < lengthInSamples; ++i) {
>             bufferData[i] = (2*Math.random() - 1);
>         }
>         On Sat, Jul 14, 2012 at 12:26 PM, Matt Diamond
>         <mdiamond@jhu.edu <mailto:mdiamond@jhu.edu>> wrote:
>             Hey all,
>             Put together a little experiment in synthesizing an
>             ambient sound texture using the Web Audio API:
>             http://matt-diamond.com/drone.html
>             Matt

Received on Thursday, 19 July 2012 13:31:54 UTC

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