Bug 254731

Summary:	[GTK][GStreamer] VA+DMABuf higher than expected usage for AV1 videos
Product:	WebKit	Reporter:	Kdwk <kdwkleung>
Component:	WebKitGTK	Assignee:	Nobody <webkit-unassigned>
Status:	RESOLVED WORKSFORME
Severity:	Normal	CC:	bugs-noreply, philn
Priority:	P2
Version:	WebKit Nightly Build
Hardware:	PC
OS:	Linux

Description Kdwk 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%.

Comment 1 Philippe Normand 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.

Comment 2 Kdwk 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