How to program videomixer using Gstreamer C API
Nicolai Hess
nicolaihess at web.de
Sat Jan 7 13:14:45 PST 2012
2012/1/6 Dejan Tolj <dejan1 at gmail.com>
> I am trying to simulate the following gstreamer pipeline using the C API:
>
> gst-launch -e videomixer name=mix ! ffmpegcolorspace ! xvimagesink \
> videotestsrc pattern=1 ! video/x-raw-yuv,width=100,height=100 !
> videobox border-alpha=0 top=0 left=0 ! mix. \
> videotestsrc pattern=0 ! video/x-raw-yuv,width=100,height=100 !
> videobox border-alpha=0 top=0 left=-100 ! mix.
>
> So far I have:
>
> #include <gst/gst.h>
> #include <glib.h>
>
>
> static gboolean
> bus_call (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);
> break;
>
> case GST_MESSAGE_ERROR: {
> gchar *debug;
> GError *error;
>
> gst_message_parse_error (msg, &error, &debug);
> g_free (debug);
>
> g_printerr ("Error: %s\n", error->message);
> g_error_free (error);
>
> g_main_loop_quit (loop);
> break;
> }
> default:
> break;
> }
>
> return TRUE;
> }
>
>
> int
> main (int argc,
> char *argv[])
> {
> GMainLoop *loop;
>
> GstElement *pipeline;
> GstElement *source1,*source2;
> GstElement *scale,*filter;
> GstElement *videobox1,*videobox2; //just one.
> GstElement *mixer,*clrspace,*sink;
> GstCaps *filtercaps;
> GstBus *bus;
>
> /* Initialisation */
> gst_init (&argc, &argv);
>
> loop = g_main_loop_new (NULL, FALSE);
>
>
> /* Check input arguments */
> /*if (argc != 2) {
> g_printerr ("Usage: %s <Ogg/Vorbis filename>\n", argv[0]);
> return -1;
> }*/
>
> //gst-launch videotestsrc pattern=snow ! ximagesink
>
> /* Create gstreamer elements */
> pipeline = gst_pipeline_new ("player");
> source1 = gst_element_factory_make ("videotestsrc", "source1");
> source2 = gst_element_factory_make ("videotestsrc", "source2");
> // source2 = gst_element_factory_make ("uridecodebin",
> "file-source2");
> scale = gst_element_factory_make ("videoscale", "scale");
> filter = gst_element_factory_make("capsfilter","filter");
> videobox1 = gst_element_factory_make ("videobox", "videobox1");
> videobox2 = gst_element_factory_make ("videobox", "videobox2");
> mixer = gst_element_factory_make ("videomixer", "mixer");
> clrspace = gst_element_factory_make ("ffmpegcolorspace",
> "clrspace");
>
> // demuxer = gst_element_factory_make ("oggdemux", "ogg-demuxer");
> // decoder = gst_element_factory_make ("vorbisdec",
> "vorbis-decoder");
> // conv = gst_element_factory_make ("audioconvert", "converter");
> sink = gst_element_factory_make ("xvimagesink", "sink");
>
> /*if (!pipeline || !source || !demuxer || !decoder || !conv || !sink) {
> g_printerr ("One element could not be created. Exiting.\n");
> return -1;
> }*/
> if (!pipeline || !source1 || !source2 || !sink) {
> g_printerr ("One element could not be created. Exiting.\n");
> return -1;
> }
>
> filtercaps = gst_caps_new_simple ("video/x-raw-yuv",
> "width", G_TYPE_INT, 200,
> "height", G_TYPE_INT, 100,
> NULL);
> g_object_set (G_OBJECT (filter), "caps", filtercaps, NULL);
> //gst_caps_unref (filtercaps);
>
> g_object_set(videobox1,"border-alpha",0,"top",0,"left",0,NULL);
> g_object_set(videobox2,"border-alpha",0,"top",0,"left",-200,NULL);
>
>
> /* Set up the pipeline */
>
> /* we set the input filename to the source element */
> g_object_set (G_OBJECT (source1), "pattern", 0, NULL);
> g_object_set (G_OBJECT (source2), "pattern", 1, NULL);
>
> /* we add a message handler */
> bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
> gst_bus_add_watch (bus, bus_call, loop);
> gst_object_unref (bus);
>
> /* we add all elements into the pipeline */
> gst_bin_add_many (GST_BIN (pipeline),
> source1,filter,videobox1,mixer,clrspace, sink,
> source2,videobox2, NULL);
>
> /* we link the elements together */
> //gst_element_link_many (source1, scale, filter, videobox1, mixer,
> clrspace, sink);
> //gst_element_link_many (source2, scale, filter, videobox2, mixer,
> clrspace, sink);
> gst_element_link_many (source1, filter, videobox1, mixer, clrspace,
> sink);
> gst_element_link_many (source2, filter, videobox2, mixer, clrspace,
> sink);
>
>
> /* Set the pipeline to "playing" state*/
> gst_element_set_state (pipeline, GST_STATE_PLAYING);
>
> /* Iterate */
> g_print ("Running...\n");
> g_main_loop_run (loop);
>
> /* Out of the main loop, clean up nicely */
> g_print ("Returned, stopping playback\n");
> gst_element_set_state (pipeline, GST_STATE_NULL);
>
> g_print ("Deleting pipeline\n");
> gst_object_unref (GST_OBJECT (pipeline));
>
> return 0;
> }
>
>
> I have also set debugging on: export GST_DEBUG=3
>
> When I run my program I get the following error:
>
> Running...
> 0:00:00.178663884 4797 0x8937020 WARN basesrc
> gstbasesrc.c:2582:gst_base_src_loop:<source2> error: Internal data
> flow error.
> 0:00:00.178766444 4797 0x8937020 WARN basesrc
> gstbasesrc.c:2582:gst_base_src_loop:<source2> error: streaming task
> paused, reason not-linked (-1)
> Error: Internal data flow error.
> Returned, stopping playback
> 0:00:00.202571746 4797 0x893ae00 WARN basetransform
> gstbasetransform.c:1627:gst_base_transform_prepare_output_buffer:<clrspace>
> pad-alloc failed: wrong-state
> 0:00:00.202645907 4797 0x893ae00 WARN basetransform
> gstbasetransform.c:2335:gst_base_transform_handle_buffer:<clrspace>
> could not get buffer from pool: wrong-state
> Deleting pipeline
>
>
> Why is it complaining about source2 not-linked?
> _______________________________________________
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> gstreamer-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>
// linking source2 with filter doesn't work, because filter is already
linked with source1
gst_element_link_many (source2, filter, videobox2, mixer, clrspace, sink,
NULL);
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