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Re: jack (1 and 2) latency reporting

by Fons Adriaensen-2 :: Rate this Message:

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On Thu, Dec 09, 2010 at 09:25:38PM +0100, Robin Gareus wrote:

> While doing the http://wiki.linuxaudio.org/wiki/jack_latency_tests with
> Luis (see thread " Differences in latency between USB and internal audio
> interfaces") I stumbled upon a small inconsistency in latency reporting
> of both jack1 and jack2mp:
>
> during start-up JACK reports (with '-n3'):
>
>   ALSA: use 3 periods for capture
>   ALSA: use 3 periods for playback
>
> However querying the physical port latency with
> jack_port_get_latency() (or `jack_lsp -l`) JACK says e.g. for
> '-n3 -p1024':
>
>  system:capture_1
>       port latency = 1024 frames
>  system:playback_1
>       port latency = 2048 frames
>
> AFAIU it the startup-message should read:
> _1_ period of latency for capture, _2_ for playback.
>
> I did not look into the code and I might be wrong, but I guess you
> cracks will know.. it seems to be a rather small bug in the
> startup-message (for the ALSA backend).
>
> The quaint part is that it is present in both JACK1 and JACK2, so maybe
> I'm just interpreting these values wrong ?!

After reading this 10 times I still fail to see the problem
or inconsistency...

Ciao,

--
FA

There are three of them, and Alleline.

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