无法在gstreamer中向管道添加过滤器

Question

I'm trying to do the exercise at the end of the Basic GStreamer tutorial here: Basic Tutorial 2 . The exercise is merely to add a filter to a video. The exercise says to simply add the "vertigoTV" effect, so I did that.

Here are the relevant parts to my attempt:

    #include <gst/gst.h>

int main(int argc, char *argv[]) {
  GstElement *pipeline, *source, *filter, *convert, *sink;
  GstBus *bus;
  GstMessage *msg;
  GstStateChangeReturn ret;

  /* Initialize GStreamer */
  gst_init (&argc, &argv);

  /* Create the elements */
  source = gst_element_factory_make ("videotestsrc", "source");
  filter = gst_element_factory_make ("vertigotv", "filter");
  sink = gst_element_factory_make ("autovideosink", "sink");

  /* Create the empty pipeline */
  pipeline = gst_pipeline_new ("test-pipeline");

  if (!pipeline || !source || !filter || !sink) {
    g_printerr ("Not all elements could be created.\n");
    return -1;
  }

  /* Build the pipeline */
  gst_bin_add_many (GST_BIN (pipeline), source, filter, sink, NULL);
  if (gst_element_link_many (source, filter, sink, NULL) != TRUE) {
    g_printerr ("Could not link all elements.\n");
    gst_object_unref (pipeline);
    return -1;
  }

  /* Modify the source's properties */
  g_object_set (source, "pattern", 0, NULL);

  /* Start playing */
  ret = gst_element_set_state (pipeline, GST_STATE_PLAYING);
  if (ret == GST_STATE_CHANGE_FAILURE) {
    g_printerr ("Unable to set the pipeline to the playing state.\n");
    gst_object_unref (pipeline);
    return -1;
  }

  /* Wait until error or EOS */
  bus = gst_element_get_bus (pipeline);
  msg = gst_bus_timed_pop_filtered (bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_EOS);

  /* Parse message */
  if (msg != NULL) {
    GError *err;
    gchar *debug_info;

    switch (GST_MESSAGE_TYPE (msg)) {
      case GST_MESSAGE_ERROR:
        gst_message_parse_error (msg, &err, &debug_info);
        g_printerr ("Error received from element %s: %s\n", GST_OBJECT_NAME (msg->src), err->message);
        g_printerr ("Debugging information: %s\n", debug_info ? debug_info : "none");
        g_clear_error (&err);
        g_free (debug_info);
        break;
      case GST_MESSAGE_EOS:
        g_print ("End-Of-Stream reached.\n");
        break;
      default:
        /* We should not reach here because we only asked for ERRORs and EOS */
        g_printerr ("Unexpected message received.\n");
        break;
    }
    gst_message_unref (msg);
  }

  /* Free resources */
  gst_object_unref (bus);
  gst_element_set_state (pipeline, GST_STATE_NULL);
  gst_object_unref (pipeline);
  return 0;
}

However, the return value is a GST_STATE_CHANGE_FAILURE. Any idea why?

Thanks so much!

Answer 1

过滤后添加视频转换：

gst-launch-1.0 videotestsrc ! vertigotv ! videoconvert ! autovideosink

Answer 2

This will definitely work, I have tried and got it working.

Please try some other steps or add the exact error you got. You may also want to post the complete code.

PS - wanted to add this as comment but fall short of 2 rep