Re: [LAU] Estimating JACK latency

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To: <linux-audio-user@...>
Date: Thursday, May 3, 2012 - 10:15 am

On Wed, May 02, 2012 at 04:51:03PM -1000, Joel Roth wrote:

Which is not completely wrong, just a little inaccurate.

Suppose you configure for 2 periods. The the following happens:

Capture A B C D E F
Processing - A B C D E
Playback - - A B C D

For 3 periods, this becomes:

Capture A B C D E F
Processing - A B C D E
Playback - - - A B C

And for 4 periods:

Capture A B C D E F
Processing - A B C D E
Playback - - - - A B

The advantage of having more that 2 periods is that processing
can be late without ill consequences, e.g. for 3 periods

Capture A B C D E F
Processing - - A B C D
Playback - - - A B C

still works fine. That is, the ALSA API allows this. It's not 100%
clear to me if Jack would allow it, as it has some internal checks
for things being 'on time'.

Jack2's async mode (also the default) adds one period of latency,
things are as if you had configured for one more period. That is
because of doing

1. Read from capture device
2. Process
3. Write to playback device

in each cycle, it does

1. Read from capture device
2. Write result of previous cycle to playback device
3. Process

Ciao,

--
FA

A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)

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Messages in current thread:
[LAU] Estimating JACK latency, S. Massy, (Mon Apr 16, 7:33 pm)
Re: [LAU] Estimating JACK latency, Paul Davis, (Mon Apr 16, 8:54 pm)
Re: [LAU] Estimating JACK latency, Joel Roth, (Sun May 13, 12:21 pm)
Re: [LAU] Estimating JACK latency, Paul Davis, (Sun May 13, 12:46 pm)
Re: [LAU] Estimating JACK latency, S. Massy, (Mon Apr 16, 9:24 pm)
Re: [LAU] Estimating JACK latency, Fons Adriaensen, (Tue Apr 17, 5:10 pm)
Re: [LAU] Estimating JACK latency, Joel Roth, (Thu May 3, 2:52 am)
Re: [LAU] Estimating JACK latency, Fons Adriaensen, (Thu May 3, 10:15 am)
Re: [LAU] Estimating JACK latency, S. Massy, (Thu May 3, 4:54 pm)
Re: [LAU] Estimating JACK latency, Joel Roth, (Thu May 3, 8:36 pm)
Re: [LAU] Estimating JACK latency, Joel Roth, (Thu May 3, 2:27 am)
Re: [LAU] Estimating JACK latency, Robin Gareus, (Thu May 3, 8:21 am)
Re: [LAU] Estimating JACK latency, Paul Davis, (Mon Apr 16, 9:38 pm)