VCE encoding slow when GPU is not stressed (HD 7970M)
Submitted by Christoph Haag
Assigned to Default DRI bug account
This is on an intel + radeon laptop, so I need to run encoding with gstreamer with DRI_PRIME=1.
Here is an example video: http://www.sample-videos.com/video/mp4/720/big_buck_bunny_720p_1mb.mp4
DRI_PRIME is doing a good job of waking up the GPU from runpm when needed for encoding via VAAPI and OMX, but for comparison I'll run glxgears both times.
I'm encoding the mentioned example video with VAAPI with this exact command: $ time DRI_PRIME=1 LIBVA_DRIVER_NAME=radeonsi gst-launch-1.0 -e filesrc location=big_buck_bunny_720p_1mb.mp4 ! qtdemux ! h264parse ! avdec_h264 ! queue ! videoconvert ! queue ! video/x-raw,format=NV12 ! vaapih264enc ! h264parse ! matroskamux ! filesink location=output.mkv
For low GPU stress I run the gst pipeline while glxgears with vsync is running: $ DRI_PRIME=1 glxgears Result: 0.75s user 0.33s system 2% cpu 52.779 total
For higher GPU stress I run the gst pipeline while glxgears without vsync is running: $ DRI_PRIME=1 vblank_mode=0 glxgears Result: 0.99s user 0.28s system 43% cpu 2.928 total
I also tried a very similar pipeline with OMX: $ time DRI_PRIME=1 gst-launch-1.0 -e filesrc location=big_buck_bunny_720p_1mb.mp4 ! qtdemux ! h264parse ! avdec_h264 ! queue ! videoconvert ! queue ! video/x-raw,format=NV12 ! omxh264enc ! h264parse ! matroskamux ! filesink location=output.mkv
Low GPU stress: 0.96s user 0.24s system 19% cpu 6.298 total High GPU stress: 1.10s user 0.24s system 141% cpu 0.949 total
Overall OMX encoding does a lot better, but it's still a large difference and still below "real time" for the 5 second video.