v4l2src set to PLAYING failure

[Frank Du]

Hello,

 

I have a problem with v4l2src plugin.

 

It works perfectly: “gst-launch-0.10 �v v4l2src ! ffmpegcolorspace !
xvimagesink”

 

But the following codes failed to work:

 

 

 

gst_init(NULL, NULL);

          pipeline = gst_pipeline_new("dpipeline");

          source = gst_element_factory_make("v4l2src", "dsrc");

          csp = gst_element_factory_make("ffmpegcolorspace", "dcsp");

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

          bus = gst_pipeline_get_bus(GST_PIPELINE(pipeline));

 

          g_object_set(G_OBJECT(source), "device", “/dev/video0”, NULL);

          gst_bin_add_many(GST_BIN(pipeline), source, csp, sink,
NULL);

          gst_bus_add_watch(bus, G_CALLBACK(bus_callback), pipeline);

          gst_object_unref(bus);

 

          gst_element_link(source, csp);

 

caps = gst_caps_new_simple("video/x-raw-yuv",

                   "format", GST_TYPE_FOURCC,
GST_MAKE_FOURCC('U','Y','V','Y'),

                    "width", G_TYPE_INT, 720,

                    "height", G_TYPE_INT, 480,

                    NULL);

         if (!gst_element_link_filtered(csp, sink, caps))

         {

             printf("UYVY Format Not Supported.\n");

             return NULL;

         }

         else

         {

             printf("Image Format Setting Finished.\n");

         }

          gst_caps_unref(caps);

 

//       state = gst_element_set_state(GST_ELEMENT(sink),
GST_STATE_PLAYING);

//       state = gst_element_set_state(GST_ELEMENT(csp), GST_STATE_PLAYING);


//       state = gst_element_set_state(GST_ELEMENT(source),
GST_STATE_PLAYING);

          state = gst_element_set_state(GST_ELEMENT(pipeline),
GST_STATE_PLAYING);

          switch(state)

          {

                   case GST_STATE_CHANGE_SUCCESS:

                             printf("Init Capture Succeed.\n");

                             break;

                   case GST_STATE_CHANGE_FAILURE:

                             printf("Init Capture Failure.\n");

                             break;

                   case GST_STATE_CHANGE_ASYNC:

                             if(GST_STATE_CHANGE_ASYNC == state)

                             {

                                      printf("Trying to Sync...\n");

                                      state = gst_element_get_state(csp,
NULL, NULL, GST_CLOCK_TIME_NONE);

                             }

                             if (GST_STATE_CHANGE_SUCCESS == state)

                             {

                                      printf("Sync Succeed.\n");

                             }

                             else

                             {

                                      printf("Init Capture...Failure.\n");

                                      return NULL;

                             }

                             break;

                   case GST_STATE_CHANGE_NO_PREROLL:

                             printf("Init File Capture Succeed(with no
data).\n");

                             break;

                   default:

                             printf("Init File Capture Error(unknown)\n");

          }

 

 

 

In fact, when I enabled these codes respectively

 

          state = gst_element_set_state(GST_ELEMENT(sink),
GST_STATE_PLAYING);

          state = gst_element_set_state(GST_ELEMENT(csp),
GST_STATE_PLAYING);

          state = gst_element_set_state(GST_ELEMENT(source),
GST_STATE_PLAYING);

//       state = gst_element_set_state(GST_ELEMENT(pipeline),
GST_STATE_PLAYING);

 

I found that the source(v4l2src) could not be set to GST_STATE_PLAYING
(GST_STATE_PAUSED neither) state.

 

Maybe I should do some additional initialization?

 

I’ve also used filesrc and it worked well.

 

Please help me.

 

 

 

Thanks & Best Regards

  _____  

Frank Du

 


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