How to Access Rtsp Url or filename?

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Hi, suppose I have multiple streams and I want to process them in parallel and publish the results in Kafka format,
so How should I know which results belong to a specific URL or file?
I've seen the example of multi-stream processing of dlstreamer

gst-launch-1.0 \
filesrc location=${INPUT_VIDEO_FILE_1} ! decodebin ! vaapipostproc ! video/x-raw(memory:VASurface) ! \
gvadetect model=${DETECTION_MODEL} device=NPU pre-process-backend=ie nireq=4 model-instance-id=inf0 ! queue ! \
gvawatermark ! videoconvertscale ! gvafpscounter ! vaapih264enc ! h264parse ! mp4mux ! filesink location=${OUTPUT_VIDEO_FILE_1} \
filesrc location=${INPUT_VIDEO_FILE_2} ! decodebin ! vaapipostproc ! video/x-raw(memory:VASurface) ! \
gvadetect model=${DETECTION_MODEL} device=NPU pre-process-backend=ie nireq=4 model-instance-id=inf0 ! queue ! \
gvawatermark ! videoconvertscale ! gvafpscounter ! vaapih264enc ! h264parse ! mp4mux ! filesink location=${OUTPUT_VIDEO_FILE_2} \
filesrc location=${INPUT_VIDEO_FILE} ! decodebin vaapipostproc ! video/x-raw(memory:VASurface) ! 
gvadetect model={$DETECTION_MODEL_3} device=GPU pre-process-backend=vaapi-surface-sharing nireq=4 model-instance-id=inf1 ! queue ! \
gvawatermark ! videoconvertscale ! gvafpscounter ! vaapih264enc ! h264parse ! mp4mux ! filesink location=${OUTPUT_VIDEO_FILE_3} \
filesrc location=${INPUT_VIDEO_FILE_4} ! decodebin vaapipostproc ! video/x-raw(memory:VASurface) ! 
gvadetect model=${DETECTION_MODEL} device=GPU pre-process-backend=vaapi-surface-sharing nireq=4 model-instance-id=inf1 ! queue ! \
gvawatermark ! videoconvertscale ! gvafpscounter ! vaapih264enc ! h264parse ! mp4mux ! filesink location=${OUTPUT_VIDEO_FILE_4}

but this example saves the result in separate files, I want the name of the source (URL or filename) published with results in Kafka.
How should I do this?
there is a similar issue #334 but couldn't find the answer