It was enabled once by Bug 1780138. But it was soon disabled again because of Bug 1787293. But for improving video playback performance, we want to enable it on release.

A cause of Bug 1787293 is not clear yet. And we failed to reproduce the problem on our PCs.
Somehow, the problem does not happen on intel GPUs.

I wonder if Bug 1778560 and Bug 1792015 might be related to the bug. At first, wait at RenderCompositorANGLE::WaitForGPU() happened on both bugs, then Bug 1793388 disabled a wait at RenderCompositorANGLE::WaitForGPU() on Windows nightly.

But the problem of Bug 1792015 still happens. Then asking to a reporter for taking profile.

Enable zero copy hardware decoded video could be split to 2 steps.

• [1] enable "reuse decoder device"
• [2] enable "zero copy hardware decoded video"

(In reply to Sotaro Ikeda [:sotaro] from comment #1)

then Bug 1793388 disabled a wait at RenderCompositorANGLE::WaitForGPU() on Windows nightly.

Bug 1793388 also added profile marker for reporting a number of pending frames.

• https://searchfox.org/mozilla-central/rev/bfa4dfd40b8fe6f1a6504e86b5ad2c5fd402bfc0/gfx/webrender_bindings/RenderCompositorANGLE.cpp#805

(In reply to Sotaro Ikeda [:sotaro] from comment #2)

Enable zero copy hardware decoded video could be split to 2 steps.

• [1] enable "reuse decoder device"
• [2] enable "zero copy hardware decoded video"

Bug 1796527 is created for [1].

I happened to be here by chance, not sure if it's right place to write this but I believe this will fix even this bug I have reported some time ago: https://bugzilla.mozilla.org/show_bug.cgi?id=1594677

Actually I'm running this test flags enabled:
media.wmf.zero-copy-nv12-textures-force-enabled TRUE
gfx.webrender.dcomp-video-overlay-win-force-enabled TRUE
gfx.direct3d11.reuse-decoder-device-force-enabled TRUE

I have set them more than two months and (referring to my bug report) my gpu clocks are not jumping around as I had reported there. Not sure if they can bring some issues but so far I haven't encountered any particular problems.
I'm running firefox stable 106.0.5 on windows 11 21h2 build 22000.1219. My main hardware are Ryzen 5800x, 32GB RAM and RTX2080S. Let me know if I can help testing.