Re: AudioParam constructor

On Tue, Jun 7, 2011 at 8:27 PM, Chris Rogers <crogers@google.com> wrote:

>
>
> On Mon, Jun 6, 2011 at 1:48 PM, Jussi Kalliokoski <
> jussi.kalliokoski@gmail.com> wrote:
>
>> Yeah, that being the main case and also that of abstraction layers, such
>> as if someone wrote, for instance something called a MixerNode, that uses
>> gain nodes to take multiple inputs and such, maybe AUXes or whatever. Also,
>> now that I think of it, it would be pretty handy if AudioParam was an
>> instance of EventTarget, so you could add listener hooks to such things as
>> onChange or onAutomationEnd (I don't know about this one), don't you think?
>> It might complicate the thing a bit, but at the benefit of hackability, and
>> that's always a good thing if you want to attract developers.
>
>
> Hi Jussi, with automation the AudioParam value can change for every single
> sample-frame, so I think it would be pretty dramatic to have an
> EventListener get called thousands of times a second!  Instead, I think it
> should be possible to query the AudioParam for its value at any exact time.
>

You're right. However this makes me think of interaction with UI elements
such as knobs, could there be some call like AudioParam.scheduleValue
(that's a stupid name for it, but...) that would define the value of that
AudioParam relative to the time of calling, so that you could get a smooth
change in the value instead of change on every buffer fill callback?


>
>
>
>
>
>> Also, now that I'm asking, can you dereference AudioParams? For example,
>> make two separate AudioGainNodes and make them share the AudioParam for
>> .gain? As here:
>>
>> var gain1 = ctx.createGainNode();
>> var gain2 = ctx.createGainNode();
>> gain1.gain = gain2.gain;
>> gain1.gain.value = 0.5;
>>
>
>
>>
>> And that would change the value of both? I could've just tried, but quite
>> honestly I'm pretty ill and tired, so I'll just ask. :)
>>
>
> I believe this should work.
>

Great!


>
>
>>
>> I think that would be a useful feature to have, if it's not that way.
>> After all, it only follows the same logic as do most things in javascript,
>> for example being able to do Array.prototype.slice.call(arguments, 1); sorta
>> things.
>>
>> I realize these things have many complicating effects,
>> implementation-wise, but I'm just throwing things at you and the rest of us,
>> to see whether you think they're good ideas or not.
>>
>> Another thing about AudioParam on my mind may be completely absurd, the
>> fever talking and impossible to implement (I'm not sure if V8 for instance
>> allows that, without changing the toString), but what if the primitive of
>> AudioParam was the value of it? That way one could use normal number values
>> in stead of AudioParams, if one pleases, and yet not making horrible
>> performance sacrifices in checking whether it's an audio param or not on
>> every sample, for example:
>>
>> sample = sample * myGainlikeEffect.gain;
>>
>> versus
>>
>> sample = sample * (isNaN(myGainlikeEffect.gain) ?
>> myGainlikeEffect.gain.value : myGainlikeEffect.gain.value);
>>
>> This would be similar to behaviour of Date(), as +new Date does the same
>> trick as (new Date).getTime().
>>
>
> I'll have to think about this one, but I'm not sure I understand your
> example here.  If you want to use the time-varying AudioParam values over a
> time-range,then I think it might be better to have a method to get the
> values into a Float32Array, then work from there.
>

Actually that's a far better idea!


>
>
>
>>
>> I'm sorry not having brought up these things earlier, but such things come
>> to mind only when you have a working prototype to play with.
>>
>> Jussi
>>
>> On Mon, Jun 6, 2011 at 9:33 PM, Chris Rogers <crogers@google.com> wrote:
>>
>>> Hmmm, that's an interesting idea.  I assume you're talking in the context
>>> of a JavaScriptAudioNode?  In this case, I can see where it might be useful
>>> to add your own AudioParams to the JavaScriptAudioNode, then they could be
>>> automated (envelope, fade-in/out, LFO, etc.) just like any other parameter.
>>>  If you wanted to get sample-accurate parameter data then we'd have to add
>>> another method (something like requesting to fill a Float32Array for a given
>>> time range) from AudioParam, so custom DSP code can do useful things with
>>> it...
>>>
>>> Chris
>>>
>>>
>>> On Mon, Jun 6, 2011 at 10:26 AM, Jussi Kalliokoski <
>>> jussi.kalliokoski@gmail.com> wrote:
>>>
>>>> Hello Chris, others,
>>>>
>>>> Is there a way to create an AudioParam from your code, I've tried
>>>> several things in the fashion of
>>>>
>>>> new (new webkitAudioContext).createGainNode().gain.constructor
>>>>
>>>> but I keep getting errors, like Illegal constructor. Is it possible to
>>>> do? Would be pretty handy when crafting your own effects.
>>>>
>>>> Jussi
>>>>
>>>
>>>
>>
>