I've already reported an issue where gst_app_src_set_caps(GST_APP_SRC(app->rappsrc), caps_gray); caps_gray = gst_caps_new_simple ("video/x-raw-gray", "width", G_TYPE_INT, 640, "height", G_TYPE_INT, 960, "framerate", GST_TYPE_FRACTION, 30000, 1001, NULL); causes an internal data flow error, but changing to gst_app_src_set_caps(GST_APP_SRC(app->rappsrc), caps); caps = gst_caps_new_simple ("video/x-raw-yuv", "format", GST_TYPE_FOURCC, GST_MAKE_FOURCC ('I', '4', '2', '0'), "width", G_TYPE_INT, 640, "height", G_TYPE_INT, 960, "framerate", GST_TYPE_FRACTION, 30000, 1001, NULL); runs fine. Both situations link the elements, its a run time error. Original message here: <a href="http://gstreamer-devel.966125.n4.nabble.com/video-x-raw-gray-on-appsrc-causes-internal-error-when-pipeline-runs-td3740099.html" target="_blank">http://gstreamer-devel.966125.n4.nabble.com/video-x-raw-gray-on-appsrc-causes-internal-error-when-pipeline-runs-td3740099.html</a> but I got no response. Now I'm having issues with getting a text overlay to end up on the proper frame, it may be a computer speed queuing issue, as on my quad core it seems to be always correct but on the dual core target systems the overlay gets ahead of the video as judged by a video hardware overlay on the images. We are tying to replace the video hardware overlay with a gstreamer textoverlay element. link_ok=gst_element_link_many (app->rappsrc, conv1, app->rover, rqueue, encode, mux, file, NULL); // order matters! works but seems the overlay gets ahead of the video frames on the dual core systems. Trying to get the overlay to link directly to the appsrc: link_ok=gst_element_link_many (app->rappsrc, app->rover, rqueue, conv1, encode, mux, file, NULL); The linking succeeds, but again I get an "Internal data flow error" when the pipeline runs. The textoverlay supports video/x-raw-yuv format: I420 width: [ 1, <a href="tel:2147483647" value="+12147483647" target="_blank">2147483647</a> ] height: [ 1, <a href="tel:2147483647" value="+12147483647" target="_blank">2147483647</a> ] framerate: [ 0/1, 2147483647/1 ] on sink pad and appsrc supports "any" on its src pad according to gst-inspect.