gpu-context should auto switch when switch hwdec

[Andarwinux]

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Expected behavior of the wanted feature

Example:

gpu-context=d3d11,winvk
hwdec=d3d11va

Then switch hwdec to nvdec at runtime (set hwdec nvdec) , then gpu-context should auto switch to winvk to allow hwdec=nvdec to work without error.

[kasper93]

@na-na-hi What do you think?

[Hrxn]

hwdec=nvdec requires gpu-context=winvk now? At least on Windows. Is this by design?

[philipl]

There are interops for egl and vulkan, so it doesn't have to be winvk but that is the better choice. It is possible to write a d3d11 interop but someone has to do the work

[Hrxn]

I see.. So, not some recent change mandated by newer versions of NVIDIA's Windows drivers?

[philipl]

No. Egl should still work fine but I haven't touched windows for ages.

[na-na-hi]

Note that this should also be applied when --hwdec-codecs change when --hwdec=auto is set.

To avoid unnecessary vo reconfigs, the switching meshanism needs to know which hwdec methods are compatible with which GPU contexts. AFAIK mpv doesn't maintain such a list.

I think such functionality can be done with a script. It only needs to do the following:

• Observe --hwdec and --hwdec-codecs for changes
• Compute a list of GPU contexts that is compatible with the union of all acceptable hwdecs
• Compare the context list with the current list. If different, set --gpu-context to the new list. A reconfig should trigger and try to use the hwdec.

hwdec=nvdec requires gpu-context=winvk now? At least on Windows. Is this by design?

NVDEC works with OpenGL on Windows.