GStreamer thread priority to avoid jerking

[Wolfgang Grandegger]

Hello,

I use the following pipeline to receive, display and record an MJPEG
video sream:

          gst-launch-1.0 -v \
          udpsrc port=50004 buffer-size=180000000 do-timestamp=1 \
            caps="application/x-rtp, media=(string)video, clock-rate=(int)90000, \
            encoding-name=(string)JPEG, payload=(int)26, framerate=(fraction)50/1" \
          ! rtpjitterbuffer latency=20 \
          ! rtpjpegdepay \
          ! vaapijpegdec \
          ! tee name=t
          t. ! queue ! vaapisink
          t. ! queue ! vaapih264enc ! mp4mux ! filesink location=/tmp/test.mp4

The recording to MP4 makes the video shaking/jerking on the display a
bit more. It runs "smoother" without (tee and recording)!
How can that be avoided?
Is it possible to prioritize the various threads or increase the queue
size?

Wolfgang.