opencv+gstreamer rtp stream, jpeg decoder issue

Hello,
I am trying to use gstreamer+opencv to receive an rtp stream and get it as rgb frame in opencv appsink. Yet, it works very slow and makes me question if mpp decoder is not working properly.

I send the stream from my pc using this:
   gst-launch-1.0 -v v4l2src device=/dev/video2 ! image/jpeg,width=1280,height=720  ! rtpjpegpay ! udpsink host=192.168.180.8 port=123

And I capture it in rk1808 using this:
   capturer.open(QString("udpsrc port=1234 ! application/x-rtp,encoding=JPEG,payload=26 !rtpjpegdepay !jpegparse !mppjpegdec !videoflip method=%1  !videoconvert ! appsink")

Am I doing something wrong? What could be the issue?
Is it related to mpp libraries, gst libraries, rga libraries?
Any suggestions on how to solve this?

Try it -> https://github.com/rockchip-linux/gstreamer-rockchip