Re: [LAU] ShowQ - "a QLAB for Linux"

On 08/07/2017 05:50 AM, Peter P. wrote:
> Hi Michael
> CCing LAU list,
>
> * Michael Jarosch <riotsound@email-addr-hidden> [2017-08-03 13:47]:
>> Am Donnerstag, den 03.08.2017, 02:44 +0200 schrieb Peter P.:
>>
>>> Thanks for your reply! I did build it myself from the latest git
>>> checkout and it did produce the same error.
>>
>> Damned!
>> Guess, if you'd contact Errol he wouldn't tell you something else than
>> he wrote in the bugreport... The question is: How to startup ShowQ
>> without jack-midi, right? Unfortunately, I don't know...
>
> I was wondering how to contact him (without gettig a github account) as
> I can't find an email address of his.
>
> The suggested reason for this problem was given as "ShowQ is connecting
> to Jack ports and does not care if they are audio or MIDI."
>
> In my case ShowQ lists the two jack audio ports (sinks) that my soundcard
> provides and makes audio connections to them. No midi connections are
> made.
>
> Dear list, does anyone know how I could debug or even fix this by using
> jackd tools/commands?
>
> thank you so much! P

Hi, as your output shows, I don't think it is a Jack connection error.
All of your ports listed are audio ports.
I just built and tested this app and I get this with an
  ice1712 based Delta1010 card:

ShowQ:out_1 # system:playback_1
ShowQ:out_2 # system:playback_2
ShowQ:out_3 # system:playback_3
ShowQ:out_4 # system:playback_4
ShowQ:out_5 # system:playback_5
ShowQ:out_6 # system:playback_6
ShowQ:out_7 # system:playback_7
ShowQ:out_8 # system:playback_8

These are all audio ports. If they were midi ports it would say
  midi_playback_1 etc.
ShowQ runs fine, although I did not test any operations.

According to the code in Audio::setup_ports(),
{
   const char **oports = jack_get_ports(client, nullptr,
     JACK_DEFAULT_AUDIO_TYPE, JackPortIsInput);

   for (int i = 0; i < 8 && oports[i]; ++i) {
   if (ports[i]) {
    std::cerr << jack_port_name(ports[i]) << " # " << oports[i] << '\n';
    jack_connect(client, jack_port_name(ports[i]), oports[i]);
   }
  }
}

ShowQ sets up eight client ports and tries to connect them
  to the first eight available audio Jack ports.
In your case it connects only the first four found,
  since that is all the ports you seem to have.
If there was a problem connecting a fifth port and beyond,
  Jack should have just printed a connection error and ShowQ
  should have just moved on.

So I think it is something later on causing this crash.

Curiously though, the bug report that was filed shows:
ShowQ:out_1 # system:playback_1
ShowQ:out_2 # system:playback_2
ShowQ:out_3 # a2j:Midi Through [14] (playback): Midi Through Port-0
ShowQ:out_4 # PulseAudio JACK Source:front-left
ShowQ:out_5 # PulseAudio JACK Source:front-right

That midi port should /NOT/ have been included, since ShowQ
  asks only for JACK_DEFAULT_AUDIO_TYPE.
I'm not sure why ShowQ attempted to connect to that midi port.

I've got ShowQ open in KDevelop, ready to troubleshoot.
But I'll need more information.
Is there anything else at all printed in the terminal output?

It is best if /you/ try running a debug session under KDevelop,
  or use gdb stand-alone. (I just prefer KDevelop.)
It should show you the troublesome line(s) causing the crash.

Tim.
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Received on Mon Aug 7 20:15:01 2017