This code was taken from the older vo_vaapi driver, which does
use the vaapi format list, but the new driver has no use for
these formats, as it is only interested in va surfaces that
can be mapped to wl buffers. The format doesn't enter into
it at all.
Wayland had some specific code that it used for implementing the
presentation time protocol. It turns out that xorg's present extension
is extremely similar, so it would be silly to duplicate this whole mess
again. Factor this out to separate, independent code and introduce the
mp_present struct which is used for handling the ust/msc values and some
other associated values. Also, add in some helper functions so all the
dirty details live specifically in present_sync. The only
wayland-specific part is actually obtaining ust/msc values. Since only
wayland or xorg are expected to use this, add a conditional to the build
that only adds this file when either one of those are present.
You may observe that sbc is completely omitted. This field existed in
wayland, but was completely unused (presentation time doesn't return
this). Xorg's present extension also doesn't use this so just get rid of
it all together. The actual calculation is slightly altered so it is
correct for our purposes. We want to get the presentation event of the
last frame that was just occured (this function executes right after the
buffer swap). The adjustment is to just remove the vsync_duration
subtraction. Also, The overly-complicated queue approach is removed.
This has no actual use in practice (on wayland or xorg). Presentation
statistics are only ever used after the immediate preceding swap to
update vsync timings or thrown away.
A bad person (AKA me) merged this stuff without paying close enough
attention to the code style. Reformat this to be in-line with the rest
of the wayland code and general mpv style (braces for functions on the
next line, horizontally aligning arguments, some cosmetic cleanups for
wayland_common.h, etc.).
So it turns out that mpv already has an mp_tag_str which makes a
readable string out of fourccs (drm formats are these).
drm_format_string, on the other hand, has a ton of baggage with having
to check different libdrm versions for certain headers, adding
compile-time defines (because there are no version defines in the libdrm
headers), etc. It's a lot simpler to just use what mpv already has and
it returns what you actually care about: i.e. is this format supported
or not. Fixes https://github.com/mpv-player/mpv-build/issues/184
This driver makes use of dmabuffer and viewporter interfaces
to enable efficient display of vaapi surfaces, avoiding
any unnecessary colour space conversion, and avoiding scaling
or colour conversion using GPU shader resources.
Aaron Boxer
Dudemanguy