[gst-devel] Dynamically add and remove audio sink

[Nagy István]

Thank you Matt!
I did it as you said and it worked like a charm. :)
I had to enable synchronization on fakesink if i add that first to the tee
before playback. If i don't do so i can't connect an autoaudiosink while the
pipeline is running. I get a buffer overflow error from the new sink. I
guess fakesink starts in non realtime mode as a default.

István

On Fri, Oct 15, 2010 at 6:24 AM, Gruenke, Matt <mgruenke at tycoint.com> wrote:

>  When you add an element to a bin, you must match its state to that of the
> bin.
>
>
>
> I think the proper sequence is:
>
>    1. add the element to the bin (keep in mind that a pipeline is just a
>    special kind of bin)
>    2. call gst_element_sync_state_with_parent() on the newly-added element
>    3. link in the element
>
>
>
> When I add a branch to a tee, I put everything on that branch in its own
> bin.  That way, on addition & removal, I’m just dealing with that one bin.
>
>
>
>
>
> Matt
>
>
>
>
>  ------------------------------
>
> *From:* Nagy István [mailto:nistvan.86 at gmail.com]
> *Sent:* Thursday, October 14, 2010 18:02
> *To:* gstreamer-devel at lists.sourceforge.net
> *Subject:* [gst-devel] Dynamically add and remove audio sink
>
>
>
> Hello everyone!
>
>
>
> I'm very new to GStreamer, i'm experimenting with the framework since a
> week. My current goal would be to write a radio scheduler application which
> can handle audio playback required for a web radio, stream the result with
> different encoders and optionally do audio output on a local audio hardware.
>
> I did some tests about how can i plugin different sources to an Adder so i
> can use the pipeline as an audio mixer. After finding the pad
> blocking capability of GStreamer, i could add and remove audio sources into
> the pipeline without stopping it.
> http://stackoverflow.com/questions/3899666/adding-and-removing-audio-sources-to-from-gstreamer-pipeline-on-the-go I
> want to do this with the audio outputs as well, i like to add and remove
> different audio sinks while the pipeline is running.
>
>
>
> I've added a Tee after the Adder so i can split up sources to many outputs.
> If i fire up the pipeline with an autoaudiosink (with it's own queue),
> playback works fine. If i add a fakesink to the Tee's output on the go
> (requesting a new src request pad an linking it with an another queue in the
> middle), one of my audio sources pauses the pipeline with a
>
>
>
> basesrc gstbasesrc.c:2447:gst_base_src_loop:<Buzzer1> pausing after
> gst_pad_push() = wrong-state
>
>
>
> error message in the debug output.
>
>
>
> I've tried to put a block on the Adder's source output while adding the new
> audio sink, but it wouldn't help me.
>
>
>
> Here is the code i'm working with), it's the Java rewrite of the
> StackOverflow Python script what i linked above. I don't know what to try
> next. If i put the pipeline together with two sinks before the first start,
> everything works fine.
>
>
>
> package test;
>
>
>
> import java.io.IOException;
>
> import java.util.logging.Level;
>
> import java.util.logging.Logger;
>
> import org.gstreamer.Element;
>
> import org.gstreamer.ElementFactory;
>
> import org.gstreamer.Gst;
>
> import org.gstreamer.Pad;
>
> import org.gstreamer.Pipeline;
>
> import org.gstreamer.State;
>
> public class Main {
>
>
>
>     public static void main(String[] args) {
>
>         Gst.init("RadioBeans", args);
>
>         Pipeline pipe = new Pipeline("Scheduler");
>
>
>
>         Element mixer = ElementFactory.make("adder", "Mixer");
>
>         pipe.add(mixer);
>
>
>
>         Element tee = ElementFactory.make("tee", "Splitter");
>
>         pipe.add(tee);
>
>
>
>         mixer.link(tee);
>
>
>
>         Element audioSink =
> ElementFactory.make("autoaudiosink","AudioOutput");
>
>         pipe.add(audioSink);
>
>         Element audioQueue = ElementFactory.make("queue","AudioQueue");
>
>         pipe.add(audioQueue);
>
>         tee.link(audioQueue);
>
>         audioQueue.link(audioSink);
>
>
>
>         Pad mixerLine1=mixer.getRequestPad("sink%d");
>
>         Pad mixerLine2=mixer.getRequestPad("sink%d");
>
>
>
>         Element buzzer1 = ElementFactory.make("audiotestsrc", "Buzzer1");
>
>         pipe.add(buzzer1);
>
>         buzzer1.set("freq", 1000);
>
>         Pad buzzer1src=buzzer1.getSrcPads().get(0);
>
>         buzzer1src.link(mixerLine1);
>
>
>
>         Element buzzer2 = ElementFactory.make("audiotestsrc", "Buzzer2");
>
>         pipe.add(buzzer2);
>
>         buzzer2.set("freq", 500);
>
>         Pad buzzer2src=buzzer2.getSrcPads().get(0);
>
>         buzzer2src.link(mixerLine2);
>
>
>
>         pipe.play();
>
>
>
>         try {
>
>           System.in.read();
>
>         } catch (IOException ex) {
>
>           Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null,
> ex);
>
>         }
>
>
>
>         Element fakeOutput = ElementFactory.make("fakesink", "FakeOutput");
>
>         pipe.add(fakeOutput);
>
>         Element fakeQueue = ElementFactory.make("queue","FakeQueue");
>
>         pipe.add(fakeQueue);
>
>         fakeQueue.link(fakeOutput);
>
>         tee.link(fakeQueue);
>
>
>
>         pipe.play();
>
>
>
>         System.out.println("Added fakesink");
>
>
>
>         try {
>
>           System.in.read();
>
>         } catch (IOException ex) {
>
>           Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null,
> ex);
>
>         }
>
>
>
>         buzzer1src.setBlocked(true);
>
>         buzzer1.setState(State.NULL);
>
>         buzzer1src.unlink(mixerLine1);
>
>         mixer.releaseRequestPad(mixerLine1);
>
>
>
>         System.out.println("Released buzzer1");
>
>
>
>         try {
>
>           System.in.read();
>
>         } catch (IOException ex) {
>
>           Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null,
> ex);
>
>         }
>
>
>
>         System.out.println("Stopping.");
>
>
>
>         pipe.stop();
>
>     }
>
>
>
> }
>
>
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