[FFmpeg-devel] [PATCH v4 1/5] libavutil: VAAPI infrastructure

[Timo Rothenpieler]

>> +    void *address;
>> +    // On current Intel drivers, derive gives you memory which is very slow
>> +    // to read (uncached?).  It can be better for write-only cases, but for
>> +    // now play it safe and never use derive.
> 
> Still subject to debate when we introduce a "GPU memcpy".
> 
> I think someone on this list once even posted a patch to add such a
> memcpy, but it didn't get in yet.

Related article from Intel:

https://software.intel.com/en-us/articles/copying-accelerated-video-decode-frame-buffers

It contains a ready-to-use copy-function, which just has to be converted
from intrinsics to yasm.
And propably also needs a reversed counterpart, as it's designed to copy
from uswc memory to normal system memory, while ffmpeg also needs to
copy data into such uswc buffers.

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