Re: [LAU] Basic question about use of a lowlatency kernel

From: Ralf Mardorf <ralf.mardorf@email-addr-hidden-dsl.net>
Date: Tue Feb 19 2013 - 23:51:52 EET

On Tue, 19 Feb 2013 22:16:24 +0100, Len Ovens <len@email-addr-hidden> wrote:

>
> On Tue, February 19, 2013 11:25 am, Jeff Sandys wrote:
>
>> - Sound travels ~1 foot per millisecond, 8 feet from the speaker =
>> 8ms latency
>
> latency as listed by qjackctl (for example) is one way from the card's
> buffer to jack. Double that by the time it gets back to the card. Cards
> typically add 1ms each way. So with 64f/p at 48khz the one way latency is
> 2.67 + 1ms from the analog input. This is already pretty close to that
> 8ms... and I haven't done anything with the audio yet. Add eq, tube
> emulation, box emulation, reverb, etc. and they all add more delay to the
> signal.
>
> This delay is more of a problem for live computer use than recording
> where
> monitoring can happen outside the computer. Just to compare: if I put a
> long enough cord on my bass so I can get 25 to 30 ft from my amp (to
> adjust sound on the mixer) my timing is already having problems. This
> would be about 50ft of sound travel, 25ft before I hear what the rest of
> the band is doing plus 25 feet before I hear my own instrument. I can
> notice the delay before I get to that 25feet by the way.
>
> Now if I am just listening, I can be 100 feet away and it still sounds
> fine... It is the interaction with that sound that shows up the latency,
> the time from when I do something to when I hear it. A good reason to use
> in ear monitoring on a large stage.

Fixed latency seldom is a serious issue and 10 meters for me completely
doesn't matter. When QjackCtl displays a latency of 10.7 msec and I don't
get jitter, than this only could be an issue, if I play a nice groove with
a drum sampler, then I have to feel, perhaps to sing, what I'm playing and
to ignore a little bit what I hear. For those who anyway hard quantise
even this shouldn't matter. For me issues start with minimal jitter or a
fixed latency > 10.7 msec. When talking about jitter, I'm talking about
MIDI jitter, audio jitter just will make the sound muddy, but aren't an
issue regarding to timing.
If I would be rich, I would use analog gear, that btw. has latency too. I
guess looping in effects could be a serious issue for digital recording
with higher latencies. Until now I only loop in reverb and I simply reduce
the reverb's delay by the latency time.

YMMV!
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Received on Wed Feb 20 00:15:04 2013

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