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Re: Limit in sample or ms for circular routing (Re: Minutes of Audio WG Teleconference, 2012-05-30)

From: Robert O'Callahan <robert@ocallahan.org>
Date: Fri, 1 Jun 2012 10:02:36 +1200
Message-ID: <CAOp6jLaCWYAgrDx8oDtfe0EoU9dNt3jTt=qLbWRo7b7YEnb47w@mail.gmail.com>
To: Philip Jägenstedt <philipj@opera.com>
Cc: Olivier Thereaux <olivier.thereaux@bbc.co.uk>, Audio Working Group <public-audio@w3.org>
On Fri, Jun 1, 2012 at 4:03 AM, Philip Jägenstedt <philipj@opera.com> wrote:

> To be specific, if one tries to create a loop with 0 delay, it will be
> clamped up either to a fixed number of samples (probably 64 or 128, to be
> defined) or to a fixed number of milliseconds.

What do you mean by "a loop with zero delay"? A loop with no DelayNodes
can't be rescued since you don't know where to put the delay. How is this
"clamp up" supposed to work?

> Defining it in milliseconds breaks for low sample rates, e.g. a 3 ms clamp
> at 8 KHz is just 24 samples, below the block size any implementation will
> want to use.

So, give your implementation a minimum sample rate.

(BTW is there any implementation difficulty using block sizes as low as 16?
I can't think of one, other than reduced efficiency.)

(Another approach is to just not allow loops, and I'm looking forward to
> hear what Robert O'Callahan has to say on that.)

Chris said loops were an essential feature, and I believe him. They do
interact poorly with many other features though. It's a problem.

We already have the constraint that loops must contain a certain amount of
delay. We will probably have to add more constraints on loops, e.g. that
certain high-latency processing can't be used in a loop.

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Received on Thursday, 31 May 2012 22:03:06 UTC

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