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[Bug 22723] OfflineAudioContext and ScriptProcessorNodes

From: <bugzilla@jessica.w3.org>
Date: Mon, 22 Jul 2013 16:23:03 +0000
To: public-audio@w3.org
Message-ID: <bug-22723-5429-CnWrKI5ymG@http.www.w3.org/Bugs/Public/>
https://www.w3.org/Bugs/Public/show_bug.cgi?id=22723

--- Comment #16 from Ehsan Akhgari [:ehsan] <ehsan@mozilla.com> ---
(In reply to comment #15)
> (In reply to comment #7)
> > If every node used this "wait for all inputs before running" logic, then
> > script nodes with buffer sizes greater than 128 need not impose a delay in
> > their signal paths. 
> 
> I just realized a subtlety in this. If a script processor node's
> onaudioprocess reads computed values from AudioParams, then the perceived
> k-rate for those AudioParams will be determined by the block size set for
> the script node and not the fixed 128-sample-block in the spec. Not only
> that, it will look like a filter-type script node (with input and output) is
> prescient and anticipates animated AudioParams, because the the
> onaudioprocess will only get to run once enough input chunks have
> accumulated, meaning the values of some of these k-rate AudioParams could
> already have advanced to a time corresponding to the end of the script
> node's buffer duration.

No, according to the spec the implementation must do 128-frame block processing
all the time, which means that for example if we have 1024 frames to fill up
for a ScriptProcessorNode, we need to call the block processing code 8 times,
and each k-rate AudioParam will be sampled at the beginning of each block.

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Received on Monday, 22 July 2013 16:23:05 UTC

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