Why gstreamer with vaapih264enc shows "context pad peer query failed"? - gstreamer

Question

I would like to use hardware encoding to compress a raw video file using gstreamer and vaapi. I am getting Could not initialize supporting library, which does not allow encoder to open. Possibly context pad peer query failed is the root cause for this. But I am not sure. I use the following pipeline:
gst-launch-1.0 -v filesrc location=input.raw ! videoparse width=1280 height=1024 format=yuy2 framerate=20/1 ! vaapih264enc ! h264parse ! qtmux ! filesink location=compressed.mov
Pipeline fails with message:
Setting pipeline to PAUSED ...
ERROR: Pipeline doesn't want to pause.
ERROR: from element /GstPipeline:pipeline0/GstVaapiEncodeH264:vaapiencodeh264-0: Could not initialize supporting library.
Additional debug info:
gstvideoencoder.c(1534): gst_video_encoder_change_state (): /GstPipeline:pipeline0/GstVaapiEncodeH264:vaapiencodeh264-0:
Failed to open encoder
Setting pipeline to NULL ...
Freeing pipeline ...
What am I doing wrong?
Using GST_DEBUG=3 gst-launch-1.0 --gst-debug-level=4 to start the pipeline gives me this:
INFO GST_STATES gstbin.c:2316:gst_bin_element_set_state:<vaapiencodeh264-0> current NULL pending VOID_PENDING, desired next READY
INFO GST_CONTEXT gstvaapivideocontext.c:106:context_pad_query:<vaapiencodeh264-0:src> context pad peer query failed
INFO GST_CONTEXT gstvaapivideocontext.c:106:context_pad_query:<vaapiencodeh264-0:sink> context pad peer query failed
INFO GST_CONTEXT gstvaapivideocontext.c:180:_gst_context_query:<vaapiencodeh264-0> posting `need-context' message
INFO vaapi gstvaapidisplay.c:119:libgstvaapi_init_once: gstreamer-vaapi version
WARN videoencoder gstvideoencoder.c:1534:gst_video_encoder_change_state:<vaapiencodeh264-0> error: Failed to open encoder
INFO GST_ERROR_SYSTEM gstelement.c:1879:gst_element_message_full:<vaapiencodeh264-0> posting message: Could not initialize supporting library.
INFO GST_ERROR_SYSTEM gstelement.c:1902:gst_element_message_full:<vaapiencodeh264-0> posted error message: Could not initialize supporting library.
INFO GST_STATES gstelement.c:2657:gst_element_change_state:<vaapiencodeh264-0> have FAILURE change_state return
INFO GST_STATES gstelement.c:2247:gst_element_abort_state:<vaapiencodeh264-0> aborting state from NULL to READY
INFO GST_STATES gstbin.c:2780:gst_bin_change_state_func:<pipeline0> child 'vaapiencodeh264-0' failed to go to state 2(READY)
My hardware should support this and driver seems to be installed properly:
shell:~$ vainfo
libva info: VA-API version 0.39.0
libva info: va_getDriverName() returns 0
libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/i965_drv_video.so
libva info: Found init function __vaDriverInit_0_39
libva info: va_openDriver() returns 0
vainfo: VA-API version: 0.39 (libva 1.7.0)
vainfo: Driver version: Intel i965 driver for Intel(R) Skylake - 1.7.0
vainfo: Supported profile and entrypoints
VAProfileMPEG2Simple : VAEntrypointVLD
VAProfileMPEG2Simple : VAEntrypointEncSlice
VAProfileMPEG2Main : VAEntrypointVLD
VAProfileMPEG2Main : VAEntrypointEncSlice
VAProfileH264ConstrainedBaseline: VAEntrypointVLD
VAProfileH264ConstrainedBaseline: VAEntrypointEncSlice
VAProfileH264Main : VAEntrypointVLD
VAProfileH264Main : VAEntrypointEncSlice
VAProfileH264High : VAEntrypointVLD
VAProfileH264High : VAEntrypointEncSlice
VAProfileH264MultiviewHigh : VAEntrypointVLD
VAProfileH264MultiviewHigh : VAEntrypointEncSlice
VAProfileH264StereoHigh : VAEntrypointVLD
VAProfileH264StereoHigh : VAEntrypointEncSlice
VAProfileVC1Simple : VAEntrypointVLD
VAProfileVC1Main : VAEntrypointVLD
VAProfileVC1Advanced : VAEntrypointVLD
VAProfileNone : VAEntrypointVideoProc
VAProfileJPEGBaseline : VAEntrypointVLD
VAProfileJPEGBaseline : VAEntrypointEncPicture
VAProfileVP8Version0_3 : VAEntrypointVLD
VAProfileVP8Version0_3 : VAEntrypointEncSlice
VAProfileHEVCMain : VAEntrypointVLD
VAProfileHEVCMain : VAEntrypointEncSlice
vaapi plugin seems to be properly installed as well:
gst-inspect-1.0 vaapih264enc
Factory Details:
Rank primary (256)
Long-name VA-API H.264 encoder
Klass Codec/Encoder/Video
Description A VA-API based H.264 video encoder
Author Wind Yuan <feng.yuan#intel.com>
Plugin Details:
Name vaapi
Description VA-API based elements
Filename /usr/lib/x86_64-linux-gnu/gstreamer-1.0/libgstvaapi.so
Version 1.8.3
License LGPL
Source module gstreamer-vaapi
Source release date 2016-06-09
Binary package gstreamer-vaapi
Origin URL http://bugzilla.gnome.org/enter_bug.cgi?product=GStreamer
...
Thank you for any suggestions.

Answer 1

I believe incorrect user configuration/permissions were the reason why the encoder library could not be initialized. It would be nice if knew how to find some log messages somewhere on my system to point me in that direction (it was a lucky stumble on my part).
I got hardware encoding working after changing two things: 1) the user under which I was running these command did not have the right permissions or configuration. I did not investigate what exactly yet. 2) Once I used proper user account I got an error message that suggested I use vaapipostproc before vaapih264enc to resolve chroma type that was not understood by the en.
The final pipeline command I used is: sudo -u proper_user gst-launch-1.0 filesrc location=input.raw ! videoparse width=1280 height=1024 format=yuy2 framerate=20/1 ! videoconvert ! vaapipostproc ! vaapih264enc ! qtmux ! filesink location=hardware.compressed.mov