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Re: [Bug 20698] Need a way to determine AudioContext time of currently audible signal

From: rl baxter <baxrob@gmail.com>
Date: Sat, 27 Apr 2013 02:05:28 -0700
Message-ID: <CACo9a0fs6xiZ9xbVo_kx8B==wdxe-VgigERB=NaKA4GQ=Tj+7w@mail.gmail.com>
To: Chris Rogers <crogers@google.com>
Cc: "public-audio@w3.org WG" <public-audio@w3.org>
Sorry if this is a silly question, but is AudioProcessingEvent.playbackTime
implemented yet?  I'm not seeing it, in chrome.canary (just updated to
latest version).  Is this a 'doh' on my part, or is .playbackTime still
only in the spec?


On Fri, Apr 26, 2013 at 8:00 PM, Chris Rogers <crogers@google.com> wrote:

>
>
>
> On Fri, Apr 26, 2013 at 1:29 PM, Russell McClellan <russell@motu.com>wrote:
>
>> On Apr 25, 2013, at 1:18 PM, bugzilla@jessica.w3.org wrote:
>> > - Corollary: need to document (if this is true) that currentTime
>> advances
>> > monotonically by a time quantum equal to the block size, as each block
>> is
>> > synthesized.  This is important because if true it implies that
>> > ScriptProcessingNode JS code may consult currentTime instead of
>> > event.playbackTime, and that the latter is no longer needed since it's
>> always
>> > equal to currentTime.
>>
>> As a developer, I don't understand this idea at all.
>>  ScriptProcessorNodes may (and do in all current implementations) have
>> additional latency above and beyond the rest of the audio graph.  That is,
>> the global "block currently being processed" (whatever that means) will in
>> general not have any defined relationship to the playback time of the
>> current script processor block.  Doing as you suggest here would make it
>> impossible for developers to synchronize javascript processing to other
>> audio graph processing.
>>
>
> Russell is quite right here, so that's why we have the .playbackTime
> attribute.
>
>
>>
>> Thanks,
>> -Russell
>>
>>
>
Received on Saturday, 27 April 2013 09:05:55 UTC

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