linuxaudio.org

Excerpts from Fred Gleason's message of 2011-05-04 00:20:33 +0200:

quoted text
> Howdy Folks:

>

> Here's a seemingly trivial requirement that has me stymied: I have a Jack client (external, built against 0.102.20) where it occasionally makes sense to connect an output port to an input on the same client.  QJackCtl happily makes the connection; the process callback delivers data as expected, but it's all zeros for the connected input port!  I can route the same client output port to a physical output (ALSA backend) and hear the expected audio.  Likewise, a physical capture port connected to the input on the client receives data from the card as expected.  It's only the "loopback" within the same client that doesn't want to go.

>

> At first I suspected that the JackPortIsTerminal flag might have some bearing on this, but changing this value seems to have no effect.  Am I missing something blatantly obvious here, or is this something that is just not within the scope of Jack to allow?

>

> Any pointers greatly appreciated.

>

> Cheers!

>

> |-------------------------------------------------------------------------|

> | Frederick F. Gleason, Jr. |               Chief Developer               |

> |                           |               Paravel Systems               |

> |-------------------------------------------------------------------------|

> |  ...one of the main causes of the fall of the Roman Empire was that,    |

> |  lacking zero, they had no way to indicate successful termination of    |

> |  their C programs.                                                      |

> |                                            -- Robert Firth              |

> |-------------------------------------------------------------------------|

I can't tell you about jack API stuff that might be relevant but I can

tell you that it usually works, there's nothing in jack that forbids it.

There's one thing though you should be aware of: the output will reach

the input one processing cycle after the output was produced, hence it

will be delayed. This is simply a consequence of how jack works.
Regards,

Philipp
_______________________________________________

Linux-audio-dev mailing list

Linux-audio-dev@lists.linuxaudio.org

http://lists.linuxaudio.org/listinfo/linux-audio-dev