When you use vaapipostproc in a live pipeline (such as: gst-launch-1.0 udpsrc uri=udp://239.192.133.203:5000 ! tsdemux ! mpegvideoparse ! vaapidecode ! vaapipostproc ! vaapisink ), you will see complaints about assertion failures instead of the expected decoded and deinterlaced video output. I'm working on this upstream, but I'm treating it as a blocker for uploading gstreamer1-vaapi to Fedora 20. See the external bug for details of work so far.
gstreamer1-vaapi-0.5.8-3.fc20 has been submitted as an update for Fedora 20. https://admin.fedoraproject.org/updates/gstreamer1-vaapi-0.5.8-3.fc20
gstreamer1-vaapi-0.5.8-3.fc20 has been pushed to the Fedora 20 testing repository.
gstreamer1-vaapi-0.5.8-3.fc20 has been pushed to the Fedora 20 stable repository.