Android上的gstreamer：当unfing管道时异常？

Question

I have a very strange problem in my App. The plan is to use gstreamer to play a videostream and display it on a SurfaceView. The pipeline uses glimagesink to display the video.

When my activity terminates it calls release_pipeline (set pipeline state to GST_STATE_NULL, unref it, set my reference to NULL). The unrefing results in this error and I have no idea what causes it:

 validate_display:211 error 3001 (EGL_NOT_INITIALIZED)

followed by a segfault. The application actually crashes in Android's Choreographer but I don't know where to go from there.

The SurfaceView lives inside a Fragment and has a Callback which calls surface_release in surfaceDestroyed and calls surface_update in surfaceChanged . The callback is added in onCreateView . My Objects are kept in an extern struct called jnictx. These functions are defined as:

 void surface_release()
{
    if (jnictx->gst.pipeline != NULL)
    {
        GstElement* vsink = gst_bin_get_by_name(jnictx->gst.pipeline, "vr_sink");
        gst_video_overlay_set_window_handle(GST_VIDEO_OVERLAY(vsink), (guintptr) NULL);
        gst_element_set_state(GST_ELEMENT(jnictx->gst.pipeline), GST_STATE_READY);
        gst_object_unref(vsink);
    }

    if (jnictx->gst.surface_win != NULL)
    {
        ANativeWindow_release(jnictx->gst.surface_win);
        jnictx->gst.surface_win = NULL;
    }
}

void surface_update(JNIEnv* env, jobject surface)
{
    ANativeWindow *new_window = ANativeWindow_fromSurface(env, surface);

    if (jnictx->gst.surface_win != NULL)
    {
        // Release the old reference
        ANativeWindow_release(jnictx->gst.surface_win);

        // The window did not change, just update the surface
        if (jnictx->gst.surface_win == new_window)
        {
            if (jnictx->gst.pipeline != NULL)
            {
                GstElement* vsink = gst_bin_get_by_name(jnictx->gst.pipeline, "vr_sink");

                // Supposedly we have to call this twice so the surface updates with the new values
                gst_video_overlay_expose(GST_VIDEO_OVERLAY(vsink));
                gst_video_overlay_expose(GST_VIDEO_OVERLAY(vsink));

                gst_object_unref(vsink);
            }

            // The window did not change, by unreffing it above we unreffed the
            // reference we acquired with ANativeWindow_fromSurface as well
            return;
        }
    }


    // If we reach this point the window changed and we have to set the new handle
    if (jnictx->gst.pipeline != NULL)
    {
        GstElement* vsink = gst_bin_get_by_name(jnictx->gst.pipeline, "vr_sink");

        jnictx->gst.surface_win = new_window;
        gst_video_overlay_set_window_handle(GST_VIDEO_OVERLAY(vsink), (guintptr) new_window);

        gst_object_unref(vsink);
    }
}

The code for setting up the glimagesink comes from the example found here . I should add that the pipeline is not referenced elsewhere nor do I access it anywhere without checking whether it's NULL.

I'm not sure if this is relevant but gstreamer lives inside it's own thread which uses a GMainLoop . The pipeline is created inside this thread and released when the GMainLoop is quit. I head that GLES and threads on Android are... tricky, so maybe...?

Anyway, if someone can help I'd be really grateful! If you need more code just let me know.

Answer 1

My pipeline used queues (with leaky=downstream) in the wrong places which somehow prevented the pipeline from entering PAUSED state (some elements where still in READY). Freeing the pipeline probably caused an illegal pointer access (maybe on the message bus listener) which caused said exception.

Visualizing the pipeline using GST_DEBUG_BIN_TO_DOT_FILE() helped to identify the issue (see this link ).