questions about appsink

[hugh]

There's a question about appsink,I use this pipe to
test:videotestsrc-->caps-->appsink, why the first buffer refcount is 1 more
time than others? Can it leak to memory leak? the result I got just as :
in:appsink probe buf_ref=2
out:appsink buf_ref=3
in:appsink probe buf_ref=2
out:appsink buf_ref=2
in:appsink probe buf_ref=2
out:appsink buf_ref=2
in:appsink probe buf_ref=2
out:appsink buf_ref=2
...

and the test code is :


#include<string.h>

#include<glib.h>

#include<gst/gst.h>
#include<gst/gstelement.h>
#include<gst/gstbus.h>
#include<gst/app/gstappsink.h>

GstElement *pl         = NULL;
GstElement  *source     = NULL;
GstCaps *caps           = NULL;
GstElement  *sink       = NULL;

GMainLoop *loop         = NULL;

static gboolean app_sink_probe(GstPad *pad, GstBuffer *buf, gpointer udata)
{
    GstMiniObject *tmp = GST_MINI_OBJECT(buf);
    g_print("in:appsink probe buf_ref=%d\n", tmp->refcount);
    return TRUE;
}

static GstFlowReturn appsink_new_buffer(GstAppSink *sink, gpointer
user_data)
{
    GstBuffer *buffer   = gst_app_sink_pull_buffer(sink);

    GstMiniObject *tmp  = GST_MINI_OBJECT(buffer);

    g_print("out:appsink buf_ref=%d\n", tmp->refcount);

    gst_buffer_unref(buffer);

    return GST_FLOW_OK;
}

int main()
{
	gst_init(NULL, NULL);

	loop    = g_main_loop_new(NULL, FALSE);

	pl      = gst_pipeline_new("test_pipe");

	source  = gst_element_factory_make("videotestsrc", "my_src");

	caps    = gst_caps_new_simple("video/x-raw-yuv",
	        "width", G_TYPE_INT, 640,
	        "height", G_TYPE_INT, 480,
	        "framerate", GST_TYPE_FRACTION, 25, 1,
	        NULL);

	sink    = gst_element_factory_make("appsink", "my_sink");



	if(NULL == source && NULL == sink) {
	    g_print("create the element failed\n");
	    goto quit;
	}

    g_object_set(sink,
            "emit-signals", FALSE,
            "sync", FALSE,
            "enable-last-buffer", FALSE,
            "sync", FALSE,
            NULL);

    GstAppSinkCallbacks appsink_cbs;
    memset(&appsink_cbs, 0, sizeof(GstAppSinkCallbacks));
    appsink_cbs.new_buffer = appsink_new_buffer;

    gst_app_sink_set_callbacks((GstAppSink*)sink, &appsink_cbs, NULL, NULL);

    GstPad * app_src_pad = gst_element_get_static_pad(sink, "sink");
    gst_pad_add_buffer_probe(app_src_pad, G_CALLBACK(app_sink_probe), NULL);
    gst_object_unref(app_src_pad);
    app_src_pad = NULL;

	gst_bin_add_many(GST_BIN(pl), source, sink, NULL);

	gst_element_link_filtered(source, sink, caps);

	if(GST_STATE_CHANGE_FAILURE == gst_element_set_state(pl,
GST_STATE_PLAYING)) {
	    g_print("change pipe to playing failed\n");
	    goto quit;
	}

	g_main_loop_run(loop);

	gst_element_set_state(pl, GST_STATE_NULL);

    g_main_loop_quit(loop);

	quit:
	if(NULL != source) {
	    gst_object_unref(source);
	    source = NULL;
	}

	if(NULL != sink) {
	    gst_object_unref(sink);
	    sink = NULL;
	}

	if(NULL != caps) {
	    gst_caps_unref(caps);
	    caps = NULL;
	}

	if(NULL != loop) {
	    g_main_loop_unref(loop);
	    loop = NULL;
	}

    if(pl != NULL) {
        gst_object_unref(pl);
        pl = NULL;
    }
	return 0;
}




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