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Re: [web-audio-api] OfflineAudioContext and ScriptProcessorNodes (#69)

From: Olivier Thereaux <notifications@github.com>
Date: Wed, 11 Sep 2013 07:29:38 -0700
To: WebAudio/web-audio-api <web-audio-api@noreply.github.com>
Message-ID: <WebAudio/web-audio-api/issues/69/24244234@github.com>
> [Original comment](https://www.w3.org/Bugs/Public/show_bug.cgi?id=22723#14) by Srikumar Subramanian (Kumar) on W3C Bugzilla. Sun, 21 Jul 2013 14:49:56 GMT

(In reply to [comment #7](#issuecomment-24244176))
> 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.

Again, using a buffer size of 128 would solve such rate discrepancies in reading AudioParams. In general, it is looking to me like the best way for script nodes to access AudioParams would be via some structure passed through the event instead of directly reading the AudioParam objects.

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Received on Wednesday, 11 September 2013 14:34:17 UTC

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