[QUESTION] How to add fragment metadata with kvssink Gstreamer plugin

[sinanliuAmazon]

A one liner description about the use case and what you are trying to achieve
Is it possible to add fragment metadata to the stream using kvssink element? If so can you provide a example?
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[disa6302]

@sinanliuAmazon ,

There isnt a way to set metadata with command line, but you can set it up in an application that uses kvssink. You would have to use gst_element_send_event. The event name would be kvs-add-metadata.

This portion of code should give you details on what kvssink expects:

amazon-kinesis-video-streams-producer-sdk-cpp/kinesis-video-gstreamer-plugin/src/gstkvssink.cpp

Lines 947 to 976 in 0888c66

	case GST_EVENT_CUSTOM_DOWNSTREAM: {
	const GstStructure *structure = gst_event_get_structure(event);
	std::string metadata_name, metadata_value;
	gboolean persistent;
	bool is_persist;
	if (!gst_structure_has_name(structure, KVS_ADD_METADATA_G_STRUCT_NAME)) {
	goto CleanUp;
	}
	LOG_INFO("received kvs-add-metadata event");
	if (NULL == gst_structure_get_string(structure, KVS_ADD_METADATA_NAME) ||
	NULL == gst_structure_get_string(structure, KVS_ADD_METADATA_VALUE) ||
	FALSE == gst_structure_get_boolean(structure, KVS_ADD_METADATA_PERSISTENT, &persistent)) {
	LOG_WARN("Event structure contains invalid field: " << std::string(gst_structure_to_string (structure)));
	goto CleanUp;
	}
	metadata_name = std::string(gst_structure_get_string(structure, KVS_ADD_METADATA_NAME));
	metadata_value = std::string(gst_structure_get_string(structure, KVS_ADD_METADATA_VALUE));
	is_persist = persistent;
	bool result = data->kinesis_video_stream->putFragmentMetadata(metadata_name, metadata_value, is_persist);
	if (false == result) {
	LOG_WARN("Failed to putFragmentMetadata. name: " << metadata_name << ", value: " << metadata_value << ", persistent: " << is_persist);
	}
	gst_event_unref (event);
	event = NULL;
	break;

We do not have a sample for this at the moment and we can look into, but hope this helps in the meantime.

[sinanliuAmazon]

Great, thank you very much for the prompt response, will try it out.

[disa6302]

Oh, and before that, you can create your event using gst_event_new_custom (https://gstreamer.freedesktop.org/documentation/gstreamer/gstevent.html?gi-language=c#gst_event_new_custom). This way you can populate your GstStructure which kvssink expects.

[sinanliuAmazon]

Tested, sending kvs-add-metadata event to the kvssink element works, thanks!

[richardgavel-ordinaryexperts]

We are using gst-launch-1.0 directly, vs embedding the gstreamer API into our application. Would it be possible to update the sink to have another sink parmeter similar to the stream_tags that injects fragment metadata values right after initiating the stream? Or is there another plugin which can inject events