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Re: Reviewing the Web Audio API (from webrtc)

From: Chris Rogers <crogers@google.com>
Date: Tue, 10 Apr 2012 13:51:29 -0700
Message-ID: <CA+EzO0=QbVRuwYD98nN0GCP5SMcL7_g5wPN7PDCzk=UsM98ptw@mail.gmail.com>
To: Randell Jesup <randell-ietf@jesup.org>
Cc: public-audio@w3.org
On Tue, Apr 10, 2012 at 1:38 PM, Randell Jesup <randell-ietf@jesup.org>wrote:

> On 4/10/2012 4:21 PM, Randell Jesup wrote:
>
>> Another example is an AGC, Dynamic Range Compressor, or Limiter using a
>> look-ahead
>> to avoid having to use extreme attack values.  This could induce 5, 10 or
>> more ms
>> of delay.  An extreme version of look-ahead is Rob's "ducking" example
>> for doing
>> voice-overs, where you might have 1/4, 1/2 or 1 second delay.
>>
>
> And of course the API includes DelayNodes....  Those could really mess up
> AV synchronization.  You could try to add equivalent delay on a separate
> video path, but likely they wouldn't match perfectly.  Perhaps well enough,
> but...  Also, it might be painful to re-combine them, and "correct"
> synchronization may be lost at that point (you might be stuck with however
> close you had it at the recombination point).


DelayNodes are meant for use as special effects and often are mixed with
dry/un-delayed versions of the signal.  Thus the delay nodes themselves do
not constitute latency.  It would be highly unusual to expect that video
presentation would be delayed (to somehow compensate for this special
effect) so synchronization is just not an issue in real-world use cases.

Chris


>
>
>
> --
> Randell Jesup
> randell-ietf@jesup.org
>
>
Received on Tuesday, 10 April 2012 20:51:58 GMT

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