Display Gstreamer video on Android

don-prog

Hi!
I try to display video on Android using Gstreamer like on other platforms:

        GstElement *pipeline;
        GError *error = NULL;
        pipeline = gst_parse_launch("videotestsrc ! glimagesink", &error);
        if (!pipeline) {
            ui->label->setText("error");
            return;
        }
        if(error != NULL){
            qDebug("GST error: ");
            qDebug(error->message);
        }
        else{
            qDebug("GST without errors");
        }

        gst_element_set_state(pipeline, GST_STATE_READY);

        GstElement *video_sink = gst_bin_get_by_interface(GST_BIN(pipeline), GST_TYPE_VIDEO_OVERLAY);
        if (!video_sink) {
            qDebug ("Could not retrieve video sink");
            return;
        }
        gst_video_overlay_set_window_handle(GST_VIDEO_OVERLAY(video_sink), this->ui->playback_widget->winId());
	//playback_widget - QOpenGLWidget

        gst_element_set_state(pipeline, GST_STATE_PLAYING);

But this code doesn't works, after gst_video_overlay_set_window_handle() function I get:
F libc : Fatal signal 11 (SIGSEGV), code 1, fault addr 0x5e in tid 3154 (gstglcontext)

Maybe I need to get the pointer to ANativeWindow? But how can I get this with Qt on Android?
Anyway I need to display video on Android using Gstreamer, so any help will be useful.
Thanks.

SGaist

Hi and welcome to devnet,

Did you build Qt's GStreamer backend for Android ?

don-prog

@SGaist thanks for the response!
I downloaded GStreamer for Android from https://gstreamer.freedesktop.org/data/pkg/android/, set INCLUDEPATH and LIBS flags for GStreamer libraries and got some working GStreamer samples with audio. All works fine, except display video.

SGaist

Then you should either try with their QtGstreamer module or try building Qt's GStreamer backend.

don-prog

@SGaist are you sure? Because I just get only these issues with display video(audio playback and all other pipelines works fine). If yes, then where can I find how can I do this? And is QtGstreamer(not pure Gstreamer) cross-platform?

SGaist

Displaying a video is not a simple as playing a sound especially on mobile platforms where there are restrictions on the resources available for applications.

Qt's GStreamer backend implements that part for you.

QtGstreamer can run on platforms where its dependencies can be built.

don-prog

@SGaist hm... interesting. I didn't know these details, many thanks! And how can I do this on Android?
And some clarifying for our mutual understanding: Can I do this on Windows, Linux, OS X, iOS and Android? Because I only heard about QtGstreamer on Linux.
Regards.

SGaist

Do you mean build Qt's GStreamer backend for Android ?

You have to check the availability of the module's dependencies for these platform (or build them by hand)

don-prog

@SGaist ok, and can you share some simple example how can I build Qt's GStreamer backend for Android? Because I even don't know how I can start.

SGaist

Sorry, I don't have an example by hand but based on the QtMultimedia sources, the first thing I'd do is get gstreamer for Android and then I'd modify the plugins.pro file and add the gstreamer subdir to the list in the android scope.

don-prog

@SGaist ok, thanks. And what is the difference between QtGstreamer module and Qt's GStreamer backend?

SGaist

The QtGstreamer module is on a lower-level. It essentially provides you a nice Qt API to build your GStreamer pipelines and a set of video sync for QtWidgets and QtQuick.

don-prog

@SGaist as I understand QtGstreamer will works for my issue too, so what is more preferable? How can I use QtGstreamer? And is it cross-platform? Thanks!

SGaist

It should run on the same platforms as Qt as long as you can satisfy its dependencies.

I'd first try to build the backend. It will likely be less work.

don-prog

@SGaist understood. Thanks for the explanations. About backend:
I need download GStreamer for Android(this I already did, right?), create plugins.pro file in the my project(I don't know even what is it, but I will read) and add GStreamer dir to the list in the android scope(don't heard about this too). Is it all what I need?

SGaist

No, you have to build the plugin from the sources and then install them

don-prog

@SGaist can you share the link which describes what I need to do? Or some additional reading? I'm sorry but I really don't understand a lot of things. Where I need to set a plugins.pro? What I need to set within it? About which plugin are you said? How and where I need to install it? How connect GStreamer to all these things?

SGaist

You don't need to create any file. You have to first get the sources of the QtMultimedia module.

There you'll find the plugins folder with the matching plugins.pro file

LuJoRi

Hi don-prog!

I've had the same issue as you...displaying a GStreamer video on Android within a Qt application!
It was a hard way to find out how to get it alltogether work and it took me a long time! I wasn't able to find really useful hints about this issue.

First I also tried it with QtGStreamer, but I didn't get it work for Android. After trying and trying and trying (...) I decided to look for another way to go. By the way - for Linux the QtGStreamer worked like a charm.

As you can see at this link (https://wiki.qt.io/Qt_5.5.0_Multimedia_Backends) the multimedia backend of Qt uses different multimedia frameworks on different platforms --> GStreamer is only used for Linux and I think this decision wasn't made causeless! I don't think it will be so easy to get the Qt's GStreamer-Backend to work for Android since a Qt application for Android comes with partial other characteristics than a Qt application for Linux. That's based in the differences between the dissimilar windowing-systems of Android and Desktop-Linux.

If you display some patience I'll show you how I did it?

Greetz, Lukas

SGaist

Hi and welcome to devnet,

@LuJoRi Indeed it wasn't mad causeless because Qt uses as much as possible native frameworks.

If I understand you correctly you successfully used GStreamer on Android with Qt to do video rendering ?