Re: [Jack-Devel] Using the callback free API with self-created RT-threads

The better way would be to use the JACK RT thread and implement the real code in the function given with jack_set_process_thread. (so in your case in  JackDriver::threads). This function would use the  jack_cycle_wait/jack_cycle_signal API. Then you can create additional workers threads, and add the proper synchronization mechanism between the JACK RT "master" thread at the worker threads.

Stéphane

Le 11 sept. 2013 à 14:29, Wolfgang Lorenz <[hidden]> a écrit :

> Thanks Stéphane and Paul for your replies.
> 
> Am Tue, 10 Sep 2013 16:49:24 +0200
> schrieb Stéphane Letz <[hidden]>:
> 
>> AFAIR the jack_cycle_wait function is supposed to fail (and so properly
>> quit the thread) if the server is shutdown. On which OS are you
>> testing?
> 
> I'm on Linux (mainly Fedora) with the current stable version of JACK,
> built from the sources. (JACK 1.9.9.5, that is.)
> http://www.jackaudio.org/downloads/jack-1.9.9.5.tar.bz2
> 
>> Can you send me tour jack_cycle_wait/jack_cycle_signal based code?
> 
> I've attached an example file, with a setup similar to the project, I'm
> working on. But not quite: For simplicity I only create one thread, as
> the synchronization with other threads is not my problem ;-). Also, in
> this example I don't require RT threads. As I am currently operating
> only in user space (for testing purposes), I don't have the permissions
> anyway: The same applies to the JACK server.
> 
> The program simply sets up one thread, in which a loop is run, that
> uses jack_cycle_wait() and jack_cycle_signal(), to synchronize the
> reading and writing of audio data.
> 
>> Thanks.
>> 
>> Stéphane
> 
> Am Tue, 10 Sep 2013 10:54:57 -0400
> schrieb Paul Davis <[hidden]>:
> 
>> On Tue, Sep 10, 2013 at 10:35 AM, Wolfgang Lorenz <[hidden]> wrote:
>> 
>>> 
>>> But what I wanted to know is: Is this really the way the callback-free
>>> API is supposed to work? Does anybody else see this as a problem or bug
>>> that should be fixed?
>>> 
>> 
>> (1) for reference, ardour has used the "callback free API" for years
>> without issues (including server shutdown)
> 
> I had a look at the sources: Ardour is using the JACK-provided thread.
> That's what I wanted to avoid, as I could simply have used the callback
> API. I've tried to start it to see how it behaves, but the current
> git-version crashes instantly SIGSEGVs at startup. I currently don't
> have the time to investigate much further, but thank you for the hint.
> 
>> (2) your use of JACK sounds odd. whether you use the callback API or the
>> callback-free one, audio processing
>>       needs to be driven by the audio interface, not your code. the way
>> you have described doesn't make it
>>      clear to me that this is the case.
> 
> Please, have a look at the attached file, for an example, of how I
> wanted to use it.
> 
> 
> Greetings,
>  Wolfgang
> <jackPipe.cpp>
> Jack-Devel mailing list
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