On Android platform, when playing rtsp audio stream, the audio disappears

General Discussion
1 
        GstElement *audio_sink = gst_element_factory_make("openslessink", "audio-sink");
        if (!audio_sink) {
            GST_ERROR("Failed to create audio sink element.");
            g_main_context_pop_thread_default(data->context);
            g_main_context_unref(data->context);
            return NULL;
        }
        g_object_set(data->pipeline, "audio-sink", audio_sink, NULL);
        g_object_set(audio_sink, "sync", TRUE , NULL);
        g_object_set(data->pipeline, "latency", 200000000, NULL);