How to solve a RAW stream playback problem with GStreamer and VAAPi - linux

Question

I am currently experiencing a small problem with GStreamer, here are more details:
Configuration:
Intel i7-6700
Intel HD Graphics 530
Ubuntu 18.04 LTS
GStreamer1.0
VAAPI plugin
I receive a UDP stream from a video source, this stream is sent in RAW UYVY format. Here is my command line to decode it:
gst-launch-1.0 -v udpsrc port="1234" caps = "application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)RAW, sampling=(string)YCbCr-4:2:2, depth=(string)8, width=(string)1920, height=(string)1080, colorimetry=(string)BT709-2, payload=(int)96, ssrc=(uint)1188110121, timestamp-offset=(uint)4137478200, seqnum-offset=(uint)7257, a-framerate=(string)25" ! rtpvrawdepay ! decodebin ! queue ! videoconvert ! xvimagesink
Problem as we can see on the screenshot below, the CPU load (right) is far too high for this kind of task and we can see the GPU load (left) which is almost zero.
To overcome this problem, I want to use the VAAPI graphics acceleration as I did in a previous project with H264 of which here is the command line below:
gst-launch-1.0 -v udpsrc port=1234 caps= "application/x-rtp, media\=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, packetization-mode=(string)1, profile-level-id=(string)640028, payload=(int)96, ssrc=(uint)2665415388, timestamp-offset=(uint)3571350145, seqnum-offset=(uint)18095, a-framerate=(string)25" ! rtph264depay ! queue ! vaapih264dec low-latency=1 ! autovideosink
The line above works perfectly and the CPU has almost no more loads. So I adapt this command line to use it with a RAW stream, here is the command:
gst-launch-1.0 -v udpsrc port="1234" caps = "application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)RAW, sampling=(string)YCbCr-4:2:2, depth=(string)8, width=(string)1920, height=(string)1080, colorimetry=(string)BT709-2, payload=(int)96, ssrc=(uint)1188110121, timestamp-offset=(uint)4137478200, seqnum-offset=(uint)7257, a-framerate=(string)25" ! rtpvrawdepay ! vaapidecodebin ! videoconvert ! xvimagesink
It is the same line as the one at the beginning but I changed the element decodebin by vaapidecodebin as I had replaced avdec_h264 by vaapih264dec for my H264 stream. Unfortunately it doesn't work and I end up with this error:
WARNING: wrong pipeline: unable to connect rtpvrawdepay0 to vaapidecodebin0
How I can solve this problem? Do you have any leads to solve this problem?

Answer 1

What exactly are you trying to accelerate here? The CPU load is probably either due to the videoconvert as this is run in software to convert UYVY into a format your renderer supports (Hopefully that's another YUV format and not RGB) or it is the data transfer of the uncompressed data from CPU memory to GPU memory.
Note that transferring uncompressed image data is a much higher data rate than compressed H.264 video.
If you think the videoconvert is the expensive part you may want to try to use OpenGL for convert and displaying: .. ! glupload ! glcolorconvert ! glimagesink.
Maybe vaapipostproc can help you with color conversion if you don't want to go the OpenGL route.