0:01:26.092525062 692 0x613800 DEBUG GST_REGISTRY gstregistry.c:587:gst_registry_add_feature:<registry0> adding feature 0x66dd40 (vaapiencode_h264)
0:01:26.092591674 692 0x613800 DEBUG GST_REFCOUNTING gstobject.c:692:gst_object_set_parent:<vaapiencode_h264> set parent (ref and sink)
0:01:26.092649185 692 0x613800 TRACE GST_REFCOUNTING gstobject.c:306:gst_object_ref_sink:<vaapiencode_h264> 0x66dd40 ref_sink 1->2
0:01:26.092719619 692 0x613800 LOG GST_REGISTRY gstregistry.c:605:gst_registry_add_feature:<registry0> emitting feature-added for vaapiencode_h264
0:01:26.092776249 692 0x613800 DEBUG GST_REGISTRY gstregistrychunks.c:709:gst_registry_chunks_load_feature: Added feature vaapiencode_h264, plugin 0x667510 vaapi
0:01:26.092835346 692 0x613800 DEBUG GST_REGISTRY gstregistrychunks.c:565:gst_registry_chunks_load_feature: Plugin 'vaapi' feature 'vaapiencode_mpeg2' typename : 'GstElementFactory'
encodebin is setting the video template for encoding. So suspecting use of encodebin element instead of vaapi element.
0:01:31.381433948 692 0x613800 DEBUG GST_REGISTRY gstregistrychunks.c:857:_priv_gst_registry_chunks_load_plugin: Added plugin 'encoding' plugin with 1 features from binary registry
0:01:31.381496083 692 0x613800 DEBUG GST_REGISTRY gstregistrychunks.c:565:gst_registry_chunks_load_feature: Plugin 'encoding' feature 'encodebin' typename : 'GstElementFactory'
0:01:31.381585734 692 0x613800 TRACE GST_REFCOUNTING gstobject.c:221:gst_object_init:<GstObject@0x675000> 0x675000 new
0:01:31.381693134 692 0x613800 LOG GST_REGISTRY gstregistrychunks.c:592:gst_registry_chunks_load_feature: Reading/casting for GstRegistryChunkElementFactory at address 0x7fb1ae245de0
0:01:31.381768742 692 0x613800 TRACE structure gststructure.c:152:gst_structure_new_id_empty_with_size: created structure 0x6774e0
                        <some are deleted here>  
0:01:31.382648680 692 0x613800 DEBUG GST_REGISTRY gstregistrychunks.c:508:gst_registry_chunks_load_pad_template: Reading/casting for GstRegistryChunkPadTemplate at address 0x7fb1ae245ee0
0:01:31.759406555 692 0x613800 DEBUG GST_REGISTRY gstregistrychunks.c:521:gst_registry_chunks_load_pad_template: Added pad_template video_%u
0:01:31.759521947 692 0x613800 DEBUG GST_REGISTRY gstregistrychunks.c:508:gst_registry_chunks_load_pad_template: Reading/casting for GstRegistryChunkPadTemplate at address 0x7fb1ae245ef8
0:01:31.759585104 692 0x613800 DEBUG GST_REGISTRY gstregistrychunks.c:521:gst_registry_chunks_load_pad_template: Added pad_template audio_%u