<div dir="ltr">Good morning, I'm making some experiments with gstreamer API and I'm trying to connect a pipeline with a dynamically created bin that has a queue and a fakesink. I created ghost pads on both sides (main pipeline and the secondary bin) but I cannot link together the two as "pads have different grandparents" error is coming up in the log.<div> This is my code:<div> </div><div>#include <stdio.h> #include <stdlib.h> #include <gst/gst.h> #define PIPELINE_MAIN_STRING "v4l2src device=\"/dev/video0\" name=\"v4l2_src_element\" ! video/x-raw,width=%d,height=%d ! tee name=split allow-not-linked=true" struct context { GstElement *main_pipeline; GstElement *main_pipeline_tee; GstPad *tee_pad; GstPad *tee_pad_ghost; GMainLoop *app_loop; GstElement *secondary_bin; GstElement *link_element_in_secondary_bin; GstPad *link_element_pad; GstPad *link_element_pad_ghost; } ctx = {0}; static int create_main_pipeline() { int ret = 0; gchar *pipeline_string = NULL; if (!(pipeline_string = g_strdup_printf(PIPELINE_MAIN_STRING, 1920, 1080))) { fprintf(stderr, "Error allocating pipeline string\n"); return -1; } fprintf(stdout, "Current pipeline string: %s\n", pipeline_string); if (!(ctx.main_pipeline = gst_parse_launch(pipeline_string, NULL))) { fprintf(stderr, "Error parsing pipeline string\n"); return -1; } if (!(ctx.main_pipeline_tee = gst_bin_get_by_name(GST_BIN(ctx.main_pipeline), "split"))) { fprintf(stderr, "Error during get of tee element\n"); return -1; } return 0; } static int create_secondary_bin() { GstElement *fakesink; if (!(ctx.secondary_bin = gst_bin_new("testbin"))) { fprintf(stderr, "Error creating secondary bin\n"); return -1; } if (!(ctx.link_element_in_secondary_bin = gst_element_factory_make("queue", "secondary_bin_queue"))) { fprintf(stderr, "Error creating queue in secondary bin\n"); return -1; } if (!(fakesink = gst_element_factory_make("fakesink", "seconday_bin_fakesink"))) { fprintf(stderr, "Error creating fakesink in secondary bin\n"); return -1; } gst_element_link(ctx.link_element_in_secondary_bin, fakesink); gst_bin_add_many(GST_BIN(ctx.secondary_bin), ctx.link_element_in_secondary_bin, fakesink, NULL); return 0; } static int request_pads() { GstPadTemplate *source_pad_template; //MAIN if (!(source_pad_template = gst_element_class_get_pad_template(GST_ELEMENT_GET_CLASS(ctx.main_pipeline_tee), "src_%u"))) { fprintf(stderr, "Error getting source pad template\n"); return -1; } if (!(ctx.tee_pad = gst_element_request_pad(ctx.main_pipeline_tee, source_pad_template, NULL, NULL))) { fprintf(stderr, "Error requesting main pipeline tee pad\n"); return -1; } if (!(ctx.tee_pad_ghost = gst_ghost_pad_new(NULL, ctx.tee_pad))) { fprintf(stderr, "Error creating ghost pad\n"); return -1; } gst_pad_set_active(ctx.tee_pad_ghost, TRUE); if (!gst_element_add_pad(ctx.main_pipeline, ctx.tee_pad_ghost)) { fprintf(stderr, "Error adding ghost pad to Main pipeline\n"); return -1; } //SECONDARY if (!(ctx.link_element_pad = gst_element_get_static_pad(ctx.link_element_in_secondary_bin, "sink"))) { fprintf(stderr, "Error requesting sink pad\n"); return -1; } if (!(ctx.link_element_pad_ghost = gst_ghost_pad_new(NULL, ctx.link_element_pad))) { fprintf(stderr, "Error creating ghost pad\n"); return -1; } gst_pad_set_active(ctx.link_element_pad_ghost, TRUE); if (!gst_element_add_pad(ctx.link_element_in_secondary_bin, ctx.link_element_pad_ghost)) { fprintf(stderr, "Error adding ghost pad to BIN\n"); return -1; } return 0; } static int connect_secondary_bin() { if (request_pads() < 0) return -1; if (!(gst_bin_add(GST_BIN(ctx.main_pipeline), ctx.secondary_bin))) { fprintf(stderr, "Error adding bin to main pipeline\n"); return -1; } if (!(gst_pad_link(ctx.tee_pad_ghost, ctx.link_element_pad_ghost))) { fprintf(stderr, "Error connecting source pad to sink pad\n"); return -1; } if (gst_element_set_state(ctx.secondary_bin, GST_STATE_PLAYING) == GST_STATE_CHANGE_FAILURE) { fprintf(stderr, "Error setting secondary bin in play mode\n"); return -1; } return 0; } int main() { gst_init(NULL, NULL); if (!(ctx.app_loop = g_main_loop_new(NULL, FALSE))) { fprintf(stderr, "Error allocating main application loop\n"); exit(1); } if (create_main_pipeline() < 0) exit(1); if (create_secondary_bin() < 0) exit(1); if (gst_element_set_state(ctx.main_pipeline, GST_STATE_PLAYING) == GST_STATE_CHANGE_FAILURE) { fprintf(stderr, "Error during set to play of pipeline\n"); exit(1); } if (connect_secondary_bin() < 0) exit(1); g_main_loop_run(ctx.app_loop); } </div><div> </div><div>And the error on the log is this:</div><div> </div><div>0:00:00.491082498 600 0xaaaaef471800 INFO GST_PADS gstpad.c:2377:gst_pad_link_prepare: trying to link pipeline0:ghostpad0 and secondary_bin_queue:ghostpad1 0:00:00.491104623 600 0xaaaaef471800 DEBUG GST_CAPS gstpad.c:2364:gst_pad_link_check_hierarchy: pads have different grandparents (NULL) and <testbin> </div></div><div> </div><div>What I did wrong?</div><div> </div><div>Thank you very much</div><div>Matteo</div></div>