Trying to add ebur128 metering metadata to my stream's audio:

	ffmpeg -i test.mp4 -filter_complex ebur128=metadata=1 -vcodec copy -acodec libfdk_aac -f nut - | ffprobe -show_frames - | more

But it doesn't seem to add the metadata.  Running a very similar command in ffbrobe using -lavfi I can see the frame metadata:

	ffprobe 2>/dev/null -f lavfi amovie=test.mp4,ebur128=metadata=1 -show_frames -show_format

Looking something like:

	TAG:lavfi.r128.M=-37.871
	TAG:lavfi.r128.S=-34.617
	TAG:lavfi.r128.I=-34.174
	TAG:lavfi.r128.LRA=7.260
	TAG:lavfi.r128.LRA.low=-38.470
	TAG:lavfi.r128.LRA.high=-31.210

But why can i not see it in my ffmpeg created stream?