Re: [Jack-Devel] how often should one call jack_port_get_latency_range()

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DateWed, 13 Jul 2011 09:34:54 -0400
From Paul Davis <[hidden] at linuxaudiosystems dot com>
ToRobin Gareus <[hidden] at gareus dot org>
CcJACK Mailing List <[hidden] at lists dot jackaudio dot org>
In-Reply-ToRobin Gareus [Jack-Devel] how often should one call jack_port_get_latency_range()
Follow-UpRobin Gareus Re: [Jack-Devel] how often should one call jack_port_get_latency_range() 
On Wed, Jul 13, 2011 at 9:30 AM, Robin Gareus <[hidden]> wrote:
> G'day!
>
> I have a JACK client with a single audio-input-port (no output). This
> input is used to parse Linear-Time-Code. For synchronization the
> application needs to know the capture-latency of said audio-port.
>
> So the question is: how often should the application call
> jack_port_get_latency_range() ?
>
> Currently it does so in every process_callback.
>
> Is this the correct solution?

no.

> The overhead may be minimal, but still it feels somewhat wrong to poll
> it during every process() cycle. Is there a callback that can be
> subscribed to to get notified of changes to port-latencies?

From the documentation of jack_set_latency_callback():

 * Tell the Jack server to call @a latency_callback whenever it
 * is necessary to recompute the latencies for some or all
 * Jack ports.
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