pipeline overflow

[James Linder]

I’d really like  a clue

my test pipeline looks like this

#!/bin/sh
# <space> not ! are significant
gst-launch-1.0 -v -e v4l2src name=source device=/dev/video2 ! \
            video/x-h264,width=1920,height=1080,framerate=30/1 ! \
	    h264parse ! mp4mux name=mux ! filesink location=myfile.mp4 \
	    pulsesrc device=alsa_input.usb-Sensoray_Co.__Inc._Sensoray_Model_2263_551645-04.analog-stereo ! lamemp3enc ! queue ! mux.

Video and audio are recorded pefectly for 30sec or so the audio drops and messages about n-thousand frames dropped and downstream is too slow to consume the data. Moving the queue about has little effect (affects time until drop). I dont understand please.
htop shows 4 cores at about 50%

James