https://bugs.freedesktop.org/show_bug.cgi?id=105145
--- Comment #8 from Christian König ckoenig.leichtzumerken@gmail.com --- (In reply to k.philipp from comment #7)
I did think about that, but it has the problem of breaking deinterlacing on all clients that do *not* set VA_SURFACE_ATTRIB_USAGE_HINT_VPP_READ (which I assume to be most) since there is - correct me if I'm wrong - at present no code to un-weave a decoded frame to fields and go back to interlaced/field mode, causing the initial issue in the first place.
Yeah, we can't do this without at least adding this frame to field conversion.
How about VA_SURFACE_ATTRIB_USAGE_HINT_EXPORT then? The VA-API hints seem to describe the use case instead of the effect, so that would match.
Now you just need to find somebody volunteering to implement that :)
Using the hint like in your proposal sounds doable to me because it's just shuffling some code around, but if we have to add de-weaving (is that even a word?) I'm probably out.
Actually not so much of a problem, IIRC we have code for this in the OMX state tracker you could just copy&paste.
Basically you allocate a new video buffer and then copy from (0,0)-(width, heigth-1) to the top field and (0,1)-(width,height) to the bottom field of the new buffer using the blitter function.
Since the blitter uses nearest pixel interpolation that should slit the frame into two fields. I can search for the code if you're interested.