how can i know data comes from which source after streammux,if a certain stream disconnect

how can i know data comes from which source after streammux,if a certain stream disconnect?
i run different duration videos,when a certain video is finished,I can’t confirm that every data comes from which video.because i do inference with 10 mats from the same stream.
And how if i use appsrc to push buffer?

As we talked, you can use streamDemux to know which stream is finished.

appsrc push buffer like this
GstBuffer *buffer = gst_buffer_new_wrapped_full()
gst_app_src_push_buffer(GST_APP_SRC(appsrc, buffer);