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Re: DynamicsCompressorNode and latency

From: Robert O'Callahan <robert@ocallahan.org>
Date: Tue, 10 Jul 2012 12:52:39 +1200
Message-ID: <CAOp6jLbkkc79seRaDZWn4VdOkGb2pjMYCQaxt+ykfnUMb_4gQQ@mail.gmail.com>
To: olivier Thereaux <olivier.thereaux@bbc.co.uk>
Cc: public-audio@w3.org
On Tue, Jul 10, 2012 at 1:36 AM, olivier Thereaux <
olivier.thereaux@bbc.co.uk> wrote:

> I'm not sure I understand how this look-ahead is any different from (and
> thus more problematic than) the buffering (and thus the delay) created by
> the JavaScriptNodes?
>
> https://en.wikipedia.org/wiki/Dynamic_range_compression#Look-ahead
> «Look-ahead is a misnomer in that the future is not actually observed.
> Instead, the input signal is split, and one side is delayed. The
> non-delayed signal is used to drive the compression of the delayed signal,
> which then appears at the output. This way a smooth-sounding slower attack
> rate can be used to catch transients. The cost of this solution is that the
> signal is delayed.»
>

Ah, so it's not really lookahead. That clarifies things, thanks.

At some point we'll need actual lookahead, and it's going to be difficult
to fit in with Web Audio, but we'll cross that when we come to it I guess.

Rob
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Received on Tuesday, 10 July 2012 00:53:08 GMT

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