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RE: audio delay node max delay time

From: Michael Schöffler <michael.schoeffler@audiolabs-erlangen.de>
Date: Thu, 16 Feb 2012 18:10:13 +0100
To: "'Chris Rogers'" <crogers@google.com>, "'Yotam Mann'" <yotammann@gmail.com>
Cc: <public-audio@w3.org>
Message-ID: <004a01cceccd$d8b9fc60$8a2df520$@audiolabs-erlangen.de>
> So the AudioContext createDelayNode() method could take an optional max
delay time which is greater than 1 second.  
> Although this value could be somewhat greater than 1 second, we may want
to consider some reasonable (but large) 
> upper limit, since it does consume memory.


Figuring out a good upper limit seems not easy to me. If I get it right, for
one second 48000samples x 4byte(float) = ~187KiB of memory is needed for
storing the delayed samples. If we set the limit to 100 seconds, a delay
node will need about 18MiB for storing the delayed samples. That’s too much
for mobile phones, but not that much on workstations. (In general) I think
the limit should be device-dependent. Using a device-dependent limit means
that the developer/script needs to know about it.  Therefore an additional
function or return value is needed.


But do we really need a delay node? A JavaScriptNode can also do the job.
Maybe some additional operations on AudioBuffer would be handy for
processing the delay (e.g. inplace copy).


(I hope my memory calculation is correct and I have no error in reasoning





Received on Thursday, 16 February 2012 17:11:17 UTC

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