[Jack-Devel] Cannot access portbuffer memory from C++

[Frank Schäfer]

Hello all,

I have written a small oscillator application in C++

Fiddling with errors and producing output to see where I am brougt me to a question:

I had only ``printf( "Processing ...\n" ); in my process callback.
My program started to produce output the moment when ``jack_activate( client );'' is called.
Isn't this a bit waste of CPU due to the fact that the process_audio callback copies plenty of data to a port which is not used yet?

I'd expect to get output from this (nothing sounding yet) program at the moment when it calls ``jack_connect''

for now I have this in my oscillator constructor:
... code snippet
...
   make_wave();
   jack_activate( client );
   //FIXME: throw exception if an error with client activation
   //FIXME: this should be placed elsewhwere and replaced by:
   //          jack_activate -> jack_connect for port connections
   //          jack_deactivate for port disconnections
   //       the process callback will be called for every activated client
   //       even no port is connected consuming unnecesary CPU power
}
...

Is this intended behavior? I'll leave the workaround in the comments in my code snippet in place then.


I am using JACK 1.9.10 on a Linux x86_64 machine
# uname -a
Linux frankies 3.13.0-79-lowlatency #123-Ubuntu SMP PREEMPT

Cheers
Frank