RESOLVED WORKSFORME254731
[GTK][GStreamer] VA+DMABuf higher than expected usage for AV1 videos 
https://bugs.webkit.org/show_bug.cgi?id=254731
Summary [GTK][GStreamer] VA+DMABuf higher than expected usage for AV1 videos
Kdwk
Reported 2023-03-30 04:19:27 PDT
On an AV1-hardware-decoding-capable machine, 1. Go to YouTube -> Settings -> Performance and Playback -> Always prefer AV1 2. Load an AV1 video 3. Observe the CPU usage of the WebProcess It needs around 5% for (suspected) VA+DMABuf AV1 decoding. This is much higher than confirmed hardware decoding (Clapper with vaav1dec uses about 2-3% CPU) but also significantly lower than confirmed software decoding (~13%). VP9 works as expected at 2-3%.
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Philippe Normand
Comment 1 2023-03-30 04:41:54 PDT
If you set GST_DEBUG="va*:6" do you see the vaav1dec element emitting logs? Might be useful to have a pipeline dump too, set GST_DEBUG_DUMP_DOT_DIR=/some/dir/ephy/can-write-on/ and attach dot files here.
Kdwk
Comment 2 2023-03-31 00:41:09 PDT
After further testing, CPU usage of AV1 videos seem to stabilize at the expected 2-3% after quite some time, so it appears that it is indeed using vaav1dec. Closing this for now
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