Setting gstreamer latency for RTSP feeds with the Java Client

[kc7b...@gmail.com]

I am playing with the kurento-player java tutorial to test and experiment with Kurento. My goal is to take RTSP video from an IP camera and play it in a browser with minimal delay. I am seeing several seconds of delay between the live video and the displayed video. It appears that it is related to the default latency by the gsreamer rtsp source. I found the following examples of how to set the latency in gstreamer:

public class GstPlayBin2Test {
 public static void main(String [] args) throws Exception {
 Gst.init("GstPlayBin2Test", args);
 
 URI uri = new URI("rtsp://127.0.0.1:8551/test");
 PlayBin2 playbin2 = new PlayBin2("GstPlayBin2Test", uri);
 
 Element videoSink = ElementFactory.make("autovideosink", "videosink");
 playbin2.setVideoSink(videoSink);
 
 playbin2.connect("notify::source", Object.class, null, new NotifySourceCallback());
 
 playbin2.play();
 
 Gst.main();
 
 playbin2.stop();
 }
 
 static class NotifySourceCallback implements GstAPI.GstCallback {
 public void callback(Element element, GParamSpec spec, Pointer user_data) {
 Element source = (Element) element.get("source");
 String sourceFactory = source.getFactory().getName();
 if ("rtspsrc".equals(sourceFactory)) {
 source.set("latency", 10000);
 }
 }
 }
}

public class PipelineLauncher {
    public static void main(String[] args) {
        args = Gst.init("PipelineLauncher", args);
 String def = "rtspsrc location=xxx name=src ! fakesink";
        Pipeline pipe = Pipeline.launch(def);
 Element rtsp = pipe.getElementByName("src");
 rtsp.set("latency", 6000);
        pipe.play();
        Gst.main();
        pipe.stop();
    }

Is there a way to do this with the Kurento Java client API? If not, how would I go about making the changes to support this feature?

Thanks, David

[Jose Antonio Santos Cadenas]

There is an open issue about this. A patch is almost done, but is missing of an interface. It is not in our short-term roadmap, but contributions are welcome.

https://github.com/Kurento/bugtracker/issues/22

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[David Robison]

Thanks. I am new to Kurento. Can you give me some pointers as how I would do this? Maybe a brief out line how one of the existing interfaces is coded. Thanks, David

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[kc7b...@gmail.com]

I am looking at providing this interface. However, I am new to Kurento and am quite unfamiliar with the code and it's layout. I'm hoping you or someone else can give me some pointers. I am looking at the solution provided here: https://gist.github.com/hunternet93/a7b4a791ce8bf2c29ccf.

Looking at the code, my best guess is that I would

1) Add a BastRtpEndpoint property in kms-core/src/server/interface/core.kmd.json

2) Add the corresponding methods in kurento-java/kurento-client/target/generated-sources/kmd/org/kurento/client/BaseRtpEndpoint.java

I'm not sure if there is anything else I need to do to define the interface. 

Finally, once in the kms-elements/src/gst-plugins/kmsplayerendpoint.c how do I get the variable that was passed in?

Any guidance, insight, or tutorial would be greatly appreciated.

Thanks, David

[Jose Antonio Santos Cadenas]

Responses inline

El mar., 9 feb. 2016 a las 20:53, <kc7b...@gmail.com> escribió:

I am looking at providing this interface. However, I am new to Kurento and am quite unfamiliar with the code and it's layout. I'm hoping you or someone else can give me some pointers. I am looking at the solution provided here: https://gist.github.com/hunternet93/a7b4a791ce8bf2c29ccf.

Looking at the code, my best guess is that I would

1) Add a BastRtpEndpoint property in kms-core/src/server/interface/core.kmd.json

Not here but in Playendpoint.kmd.json in project kms-elements 

2) Add the corresponding methods in kurento-java/kurento-client/target/generated-sources/kmd/org/kurento/client/BaseRtpEndpoint.java

Java is autogenerated, you don't need to modify it.

 

I'm not sure if there is anything else I need to do to define the interface. 

Just define the interface in kmd.json file 

Finally, once in the kms-elements/src/gst-plugins/kmsplayerendpoint.c how do I get the variable that was passed in?

Using a gobject property from PlayerEndpointImpl.cpp

 

Any guidance, insight, or tutorial would be greatly appreciated.

Thanks, David

Hope that helps.

Cheers. 

[kc7b...@gmail.com]

Where is the "Java is autogenerated, you don't need to modify it."? In which project is it generated? David

[Jose Antonio Santos Cadenas]

in the project that contains the kmd, it is not upladed to git but directly to maven during compilation in ci system. When kurento-client-java is build the source is generated using the dependencies that were updated to maven.

[kc7b...@gmail.com]

I made the changes to the kmd.json file but java does not seem to be generating its source from the new file. Any idea what I may be doing wrong? David

[Jose Antonio Santos Cadenas]

See how modules work in order to understand this proccess, this are the relevant documentation pages:

http://doc-kurento.readthedocs.org/en/latest/mastering/kurento_modules.html

http://doc-kurento.readthedocs.org/en/latest/mastering/develop_kurento_modules.html