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Re: fftSize requirement for RealtimeAnalyserNode

From: Raymond Toy <rtoy@google.com>
Date: Fri, 23 Mar 2012 09:34:02 -0700
Message-ID: <CAE3TgXERY6UcYQz=ZpUPz9JDV_D2Gi6xcqudKQfO94FHuBDp1A@mail.gmail.com>
To: Jussi Kalliokoski <jussi.kalliokoski@gmail.com>
Cc: "Wei, James" <james.wei@intel.com>, "public-audio@w3.org" <public-audio@w3.org>
On Thu, Mar 22, 2012 at 4:36 PM, Jussi Kalliokoski <
jussi.kalliokoski@gmail.com> wrote:

> On Thu, Mar 22, 2012 at 11:27 PM, Raymond Toy <rtoy@google.com> wrote:
>
>>
>
> Do you have a specific need for a non-power of two analysis?  I'm just
>> curious.
>>
>
> It just seems like an arbitrary limit. Most of the time, you probably want
> to set the length in seconds, not samples, and then you won't get a
> power-of-two.
>

Yes, I'll agree that it's an arbitrary limit.  And, yes, seconds (or more
lilkely, fractions of a second) is probably more useful and scales better
if the sample rate changes.


>
>
>> Also, FFTW uses the GPL license, so if the browser is also not GPL, there
>> are potential legal issues.  This is where you go ask a lawyer.
>>
>
> There are other ones as well (kissfft is BSD 3-clause for example, IIRC),
> but I don't think the licensing of certain FFT implementations is a valid
> argument to base the spec on.
>

No, but you mentioned using FFTW in particular which has some licensing
issues.

>
> Also, the algorithm isn't complex, you could implement it without a
> library.
>

Agreed.  But getting a fast one is complex.

Thanks for the info,

Ray
Received on Friday, 23 March 2012 16:34:34 GMT

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