QtMultimedia 5.0.0: Missing video frames while playing mp4 video using sample QtMultimedia application

We build Qt5 natively on Nvidia Tegra3 board.

using below gstreamer command, we can run sample mp4 video(HDvideo and normal video) on tegra3 successfully.
gst-launch filesrc location=video.mov ! qtdemux name=demux demux.video_00 ! nv_omx_h264dec ! nv_gl_eglimagesink demux.audio_00 ! nv_omx_aacdec ! alsasink device=hw:0,0.

However, using QtQuick Mediaplayer element and sample application qmlvideofx in Qtmultimedia examples,it throws

Warning:a lot of buffers are being dropped" and videoframes are missing while playing video.

Could you please confirm if QtMultimedia uses nv_omx_h264dec(hardware decoder) to play video or how to change the QtMultimedia to build the above pipeline?