Re: [LAU] Use of 96 kHz sample rate to lower latency

From: Harry van Haaren <harryhaaren@email-addr-hidden>
Date: Wed Jan 01 2014 - 15:56:44 EET

On Wed, Jan 1, 2014 at 1:21 PM, Joel Roth <joelz@email-addr-hidden> wrote:

> I was curious, if doubling the sample rate is a
> practical way to reduce latency for live effects
> processing. I would think it would reduce latency by half.
>

It would: you mention "practical", i'm not sure I'd call it that.

> If one wanted to avoid the tradeoff of handling twice the
> usual amount of audio data,

CPU load will go up, since there is 2x more of data to process,
which also means every plugin / host has 2x more work to do.
Adds up quickly if you're doing things like convolution reverbs
or other CPU intense processing..

I was curious if ALSA sample
> rate conversion, or some other clever hack could be used to
> get low latency advantage of the high sample rate, while
> actually dealing with 48k streams through JACK.
>
 Theoretically possible I suppose, it seems like an awful lot of
effort to get a few less ms latency..

Latency below ~3ms isn't percievable at all IMO: most will agree.
Why not run jack at 64 frames, 2 buffers? That'll achieve approx
3ms (on 44.1kHz and 48kHz).. which is fine for the purpose?

Perhaps I'm missing something, are you doing mulitple passes
trough the sound-card that you're adding its latency two or more times?

Cheers, -Harry

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Received on Wed Jan 1 16:15:13 2014

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