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Re: Help needed with a sync-problem

From: Chris Rogers <crogers@google.com>
Date: Mon, 6 Aug 2012 11:43:56 -0700
Message-ID: <CA+EzO0=j7kk6wKzgijaZDn=nq_g6ZDx-XkWhRAdJVAxNAyiz5Q@mail.gmail.com>
To: Jussi Kalliokoski <jussi.kalliokoski@gmail.com>
Cc: Chris Wilson <cwilso@google.com>, Peter van der Noord <peterdunord@gmail.com>, public-audio@w3.org
On Mon, Aug 6, 2012 at 11:06 AM, Jussi Kalliokoski <
jussi.kalliokoski@gmail.com> wrote:

> On Mon, Aug 6, 2012 at 8:09 PM, Chris Wilson <cwilso@google.com> wrote:
>> On Sat, Aug 4, 2012 at 7:05 AM, Peter van der Noord <
>> peterdunord@gmail.com> wrote:
>>> 2012/8/3 Chris Wilson <cwilso@google.com>
>>>> On Fri, Aug 3, 2012 at 10:40 AM, Peter van der Noord <
>>>> peterdunord@gmail.com> wrote:
>>>>> I agree fully that it won't be what most developers want or need to
>>>>> do, the api will be used for games and site music/effects mostly, but
>>>>> creating custom nodes would be my primary focus. To be honest, the list of
>>>>> native nodes that i wanted to use has thinned out, due to some behaviours
>>>>> and implementations that were not appropriate for what i wanted. That's all
>>>>> fine by itself, but if i can't recreate them myself...
>>>> Have you filed issues on those behaviors and implementations?
>>> I have posted quite a lot of messages to this list as i went along,
>>> commenting on things that i found when i was working with the api. Some
>>> suggestions made sense, some didn't, but to be honest this isn't really the
>>> point. Apart from the fact that i don't want the workgroup to decide
>>> whether my ideas are valid, and if they are, wait for a year for it to be
>>> implemented in a browser (and probably not exactly as i'd want it so i'd
>>> have to work around it), the main point is: i want to create my own nodes.
>>> You mention somewhere in this thread that nearly everything can be done
>>> with the native nodes, but just this isnt true. Really, it isn't. For
>>> example: there are literally hundreds of modules on sale for the Eurorack
>>> system (the most popular type of modular synthesizer, i did a really quick
>>> count on a popular store and saw about 500-600), with new ones being added
>>> every year. With your argument, you'd only need 8 types or so and would be
>>> able to do everything with those. Obviously, that is not the case.
>> There are a limited number of electric components those modules are made
>> of (resistors, capacitors, etc), so I have to disagree.  AudioNodes are not
>> a 1:1 comparison to modular synth modules - most modular synth modules
>> would combine a number of different AudioNode components, in my
>> expectation.  I still believe that scripted nodes are important to get
>> right as well, but I believe most scenarios actually CAN be satisfied with
>> a combination of native modules.
>> You mentioned the only thing you'd want would be an noise gate (iirc), a
>>> nice one indeed, but what's the use if it adds a delay to the signal?
>>> Correct me if i'm wrong, but in my opinion (or more exact: in my case) it's
>>> useless.
>> Given that noise gate would be a trivial node to implement, I'd be able
>> to get away with implementing it with a very small bufferSize, which would
>> put its delay on the order of 5-10ms.  That's still unfortunate, and I'd
>> much rather have it as a native module, yes. I'd also rather have an
>> AudioNode output of the "reduction" parameter in the DynamicsCompressor to
>> do side-chaining and ducking; but I see these as evolutionary things that
>> we're working toward, not a reason to start over and expect that everyone
>> wants to be calling matrix methods directly.
>> I know custom nodes are way slower than the native ones and i accept
>>>> that. For comparison, there's nothing native going on in the modular synth
>>>> i created in flash, although i do admit there is some trickery involved.
>>>> But still, it's the single-threaded flash player, with each module writing
>>>> buffers in plain old as3 for-loops. I have no idea how as3 compares to js
>>>> (if anyone knows, i'd be interested to hear), but if i can recreate that
>>>> same performance with js and custom-nodes, i'm quite happy. (The
>>>> openingpatch on patchwork-synth.com runs 20-30 modules or so, and most
>>>> of them are not very optimized at all; my sine-osc still does Math.sin to
>>>> create its signal and there's the same biquad filter in there coded by hand
>>>> in as3, and still the ui reacts fine)
>> And if that's how you want to implement, simply use a single JS node
>> connected for output, and continue to do everything else yourself.  A
>> single delay of 5-10ms shouldn't be a critical issue.  It seems to me that
>> you've already DONE the work to implement a lot of audio processing
>> yourself; one major goal behind Web Audio was to make that kind of
>> processing accessible to those who don't already have that code written,
>> and/or would benefit from the performance boost from having
>> natively-implemented optimized audio code running in a
>> separate-from-the-UI-thread high-priority thread.  I don't want to
>> understate the important of optimizing and insulating the audio path from
>> glitching (for example, resizing the window while your opening patch was
>> playing badly glitches on my
>> Xeon MacPro).
>> I guess what I'm trying to get at is there's a huge difference between "I
>> want to create my own programmatic modules" and "I want to create my own
>> nodes."  The vocoder, for example, is essentially a bunch of programmatic
>> modules plugged together; however, it doesn't use JSNodes at all.
> Funny that you should mention these things:
>  * Ease of use of the API.
>  * Performance benefits.
>  * The possibility of creating almost any system with native nodes.
> To me, the last point counteracts both of the former ones. Essentially,
> what you're suggesting is to make software developers think of their audio
> systems in terms of electronics and that everything can be made out of
> these components. While true, this is software and the API is going to be
> used by software developers. That means that making them think in terms of
> electronics rather than software, there's hardly any point to be made for
> ease of use. Not to mention performance.
> Your vocoder is a good example, actually. Don't take me wrong, it's a
> really cool demo. But if you compare the complexity of implementing it with
> a JavaScriptNode and DSP API, the difference is astonishing.
> In mathematical terms you could define a vocoder as `output =
> IFFT(FFT(window(input)) * FFT(window(carrier)))` and an implementation
> would be a few lines of code, whereas your vocoder is a few hundred! And
> that's even before thinking about performance or accuracy. I'm pretty
> certain an implementation even in pure JavaScript (without the DSP API)
> would outperform the setup, and even exponentially when you increase the
> number of frequency bands used.

> Cheers,
> Jussi

Jussi, old-school vocoders use more of a constant-Q approach:

So FFTs are less useful there...

Received on Monday, 6 August 2012 18:44:25 UTC

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