rookie question for writing a simple video player
Stefan Sauer
ensonic at hora-obscura.de
Wed Dec 14 01:06:12 PST 2011
On 12/13/2011 02:40 PM, jaeyong yoo wrote:
> Hello,
>
> I just read gstreamer application development manual (0.10.35.1) and
> want to write a very simple video player.
>
> I can play a video (mpeg2-encoded) using playbin in
> test/examples/manual folder thus I tried to strip out the parts that
> handle the required elements to play the particular video and wrote
> the code as follows.
if you want to write a mediaplayer use playbin2 as the only element you
need (its a toplevel pipeline and will plug whatever is needed).
Stefan
>
>
> #include <gst/gst.h>
>
>
> static void handoff (GstElement * identity, GstBuffer * frame,
> gpointer data)
> {
> printf("handoff called\n");
> }
>
> static gboolean my_bus_callback (GstBus * bus, GstMessage * msg,
> gpointer data)
> {
> GMainLoop *loop = (GMainLoop *) data;
>
> switch (GST_MESSAGE_TYPE (msg)) {
> case GST_MESSAGE_EOS:
> {
> g_print ("End-of-stream\n");
> g_main_loop_quit (loop);
> printf("JYD: bus_call: GST_MESSAGE_EOS\n");
> break;
> }
> case GST_MESSAGE_ERROR:
> {
> gchar *debug;
> GError *err;
> printf("JYD: bus_call: GST_MESSAGE_ERROR\n");
> gst_message_parse_error (msg, &err, &debug);
> g_free (debug);
> g_print ("Error:: %s\n", err->message);
> g_error_free (err);
> g_main_loop_quit (loop);
> break;
> }
> case GST_MESSAGE_WARNING:
> {
> char buf[1024];
> sprintf( buf, "%s", GST_MESSAGE_SRC_NAME(msg) );
> printf("JYD: bus_call: %s %s\n",
> GST_MESSAGE_TYPE_NAME(msg), buf);
>
> break;
> }
>
> case GST_MESSAGE_STATE_CHANGED:
> {
> printf("JYD: bus_call: (%s: %d)\n",
> GST_MESSAGE_TYPE_NAME(msg), GST_MESSAGE_TYPE(msg));
> /* TODO: how to see the changed element state? */
> break;
> }
> default:
> printf("JYD: bus_call: default (%s: %d)\n",
> GST_MESSAGE_TYPE_NAME(msg), GST_MESSAGE_TYPE(msg));
> break;
> }
> return TRUE;
> }
>
> gint main (gint argc, gchar * argv[])
> {
> GstElement *scale;
> GstElement *identity;
> GstElement *pipeline, *queue;
> GstElement *src, *dec, *conv, *sink;
> GMainLoop *loop;
> GstBus *bus;
>
> gst_init (&argc, &argv);
>
> if (argc < 2) {
> g_print ("usage: %s <media file or uri>\n", argv[0]);
> return 1;
> }
>
> /* create and event loop and feed gstreamer bus mesages to it */
> loop = g_main_loop_new (NULL, FALSE);
>
> /* create pipeline */
> pipeline = gst_pipeline_new ("pipeline");
> bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
> gst_bus_add_watch(bus, my_bus_callback, loop);
> gst_object_unref (bus);
>
> /* create an element for file-reading */
> src = gst_element_factory_make ("filesrc", "source");
> g_object_set (G_OBJECT (src), "location", argv[1], NULL);
> dec = gst_element_factory_make ("decodebin", "decode");
> queue = gst_element_factory_make ("queue", "preroll_video_src0" );
> sink = gst_element_factory_make ("autovideosink", "videosink");
> conv = gst_element_factory_make ("ffmpegcolorspace", "vconv");
> scale = gst_element_factory_make ("videoscale", "vscale");
> identity = gst_element_factory_make ("identity", "identity-for-what");
> g_object_set (identity, "silent", TRUE, NULL);
> g_signal_connect (identity, "handoff", G_CALLBACK (handoff), NULL);
>
> /* add elements to a bin */
> gst_bin_add_many( GST_BIN (pipeline), src, dec, queue, conv,
> scale, identity, sink, NULL );
>
> /* link the elements in the bin */
> gst_element_link( src, dec );
> gst_element_link( dec, queue );
> gst_element_link( queue, identity );
> gst_element_link( identity, conv );
> gst_element_link( conv, scale );
> gst_element_link( scale, sink );
>
>
> /* start the bin */
> gst_element_set_state (pipeline, GST_STATE_PLAYING);
>
> /* start play back and listed to events */
> printf("go to main loop\n"); /* XXX you may start debugging here */
> g_main_loop_run (loop);
> printf("return from main loop\n");
>
> /* cleanup */
> g_object_unref (pipeline);
> g_object_unref (loop);
>
> return 0;
> }
>
>
> and the results give me the following
>
> Error:: Internal data flow error.
> return from main loop
>
> (lt-myvideoplayer:26621): GStreamer-CRITICAL **:
> Trying to dispose element videosink, but it is in PAUSED instead of
> the NULL state.
> You need to explicitly set elements to the NULL state before
> dropping the final reference, to allow them to clean up.
> This problem may also be caused by a refcounting bug in the
> application or some element.
>
>
> (lt-myvideoplayer:26621): GStreamer-CRITICAL **:
> Trying to dispose element identity-for-what, but it is in PAUSED
> instead of the NULL state.
> You need to explicitly set elements to the NULL state before
> dropping the final reference, to allow them to clean up.
> This problem may also be caused by a refcounting bug in the
> application or some element.
>
>
> (lt-myvideoplayer:26621): GStreamer-CRITICAL **:
> Trying to dispose element vscale, but it is in PAUSED instead of the
> NULL state.
> You need to explicitly set elements to the NULL state before
> dropping the final reference, to allow them to clean up.
> This problem may also be caused by a refcounting bug in the
> application or some element.
>
>
> (lt-myvideoplayer:26621): GStreamer-CRITICAL **:
> Trying to dispose element vconv, but it is in PAUSED instead of the
> NULL state.
> You need to explicitly set elements to the NULL state before
> dropping the final reference, to allow them to clean up.
> This problem may also be caused by a refcounting bug in the
> application or some element.
>
>
> (lt-myvideoplayer:26621): GStreamer-CRITICAL **:
> Trying to dispose element preroll_video_src0, but it is in PAUSED
> instead of the NULL state.
> You need to explicitly set elements to the NULL state before
> dropping the final reference, to allow them to clean up.
> This problem may also be caused by a refcounting bug in the
> application or some element.
>
>
> GThread-ERROR **: file
> /build/buildd/glib2.0-2.30.0/./gthread/gthread-posix.c: line 171
> (g_mutex_free_posix_impl): error 'Device or resource busy' during
> 'pthread_mutex_destroy ((pthread_mutex_t *) mutex)'
> Trace/breakpoint trap
>
>
> I'm stcuked in this phase.
> Please help me.
> Any comments, reading recommendations, would be very appreciated.
>
> jaeyong
>
>
> _______________________________________________
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> gstreamer-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
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