NEW235592
[Cocoa] rVFC() callbacks have up to 60ms extra latency 
https://bugs.webkit.org/show_bug.cgi?id=235592
Summary [Cocoa] rVFC() callbacks have up to 60ms extra latency
Jer Noble
Reported 2022-01-25 08:59:01 PST
[Cocoa] rVFC() callbacks have up to 16ms extra latency
Attachments
Patch (53.89 KB, patch)
2022-01-25 09:17 PST, Jer Noble 		dino: review+
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Radar WebKit Bug Importer
Comment 1 2022-01-25 09:15:47 PST
<rdar://problem/88027149>
Jer Noble
Comment 2 2022-01-25 09:15:57 PST
Correction: 60ms extra latency.
Jer Noble
Comment 3 2022-01-25 09:17:51 PST
Created attachment 449934 [details] Patch
Jer Noble
Comment 4 2022-01-26 13:52:55 PST
Unfortunately, Performance testing shows this patch to have a negligible effect on latency. It appears latency is more greatly determined by when in a display refresh cycle the frame becomes available. The good news is that even without this patch, frame display latencies are in the order of 9-16ms.
Maciej Stachowiak
Comment 5 2022-01-31 10:43:15 PST
Is it 60ms or 9-16ms? The former seems fatal to use of the feature, the latter seems maybe ok?
Jer Noble
Comment 6 2022-01-31 11:59:42 PST
(In reply to Maciej Stachowiak from comment #5) > Is it 60ms or 9-16ms? The former seems fatal to use of the feature, the > latter seems maybe ok? Potentially 60ms, because that's the timer which AVPlayerItemVideoOutput uses to purge samples. In practice, I've never seen it higher than 16ms on this particular machine.
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