video: add vaapi decode and output support

This is based on the MPlayer VA API patches. To be exact it's based on
a very stripped down version of commit f1ad459a263f8537f6c from
git://gitorious.org/vaapi/mplayer.git.

This doesn't contain useless things like benchmarking hacks and the
demo code for GLX interop. Also, unlike in the original patch, decoding
and video output are split into separate source files (the separation
between decoding and display also makes pixel format hacks unnecessary).

On the other hand, some features not present in the original patch were
added, like screenshot support.

VA API is rather bad for actual video output. Dealing with older libva
versions or the completely broken vdpau backend doesn't help. OSD is
low quality and should be rather slow. In some cases, only either OSD
or subtitles can be shown at the same time (because OSD is drawn first,
OSD is prefered).

Also, libva can't decide whether it accepts straight or premultiplied
alpha for OSD sub-pictures: the vdpau backend seems to assume
premultiplied, while a native vaapi driver uses straight. So I picked
straight alpha. It doesn't matter much, because the blending code for
straight alpha I added to img_convert.c is probably buggy, and ASS
subtitles might be blended incorrectly.

Really good video output with VA API would probably use OpenGL and the
GL interop features, but at this point you might just use vo_opengl.
(Patches for making HW decoding with vo_opengl have a chance of being
accepted.)

Despite these issues, decoding seems to work ok. I still got tearing
on the Intel system I tested (Intel(R) Core(TM) i3-2350M). It was also
tested with the vdpau vaapi wrapper on a nvidia system; however this
was rather broken. (Fortunately, there is no reason to use mpv's VAAPI
support over native VDPAU.)

2 files changed, 35 insertions, 1 deletions

diff --git a/DOCS/man/en/options.rst b/DOCS/man/en/options.rst
index 14cb2ace67..1cfc4679fc 100644
--- a/DOCS/man/en/options.rst
+++ b/DOCS/man/en/options.rst
@@ -1052,7 +1052,8 @@
     ``<api>`` can be one of the following:
 
     :no:        always use software decoding (default)
-    :vdpau:     works with nvidia drivers only, requires ``--vo=vdpau``
+    :vdpau:     requires ``--vo=vdpau``
+    :vaapi:     requires ``--vo=vaapi``
     :vda:       OSX
     :crystalhd: Broadcom Crystal HD
 
diff --git a/DOCS/man/en/vo.rst b/DOCS/man/en/vo.rst
index 42078dd6f8..2e24b670d8 100644
--- a/DOCS/man/en/vo.rst
+++ b/DOCS/man/en/vo.rst
@@ -665,6 +665,39 @@ Available video output drivers are:
     ``switch-mode``
         Instruct SDL to switch the monitor video mode when going fullscreen.
 
+``vaapi``
+    Intel VA API video output driver with support for hardware decoding. Note
+    that there is absolutely no reason to use this, other than wanting to use
+    hardware decoding to save power on laptops, or possibly preventing video
+    tearing with some setups.
+
+    ``scaling=<algorithm>``
+        default
+            Driver default (mpv default as well).
+        fast
+            Fast, but low quality.
+        hq
+            Unspecified driver dependent high-quality scaling, slow.
+        nla
+            ``non-linear anamorphic scaling``
+
+    ``deint-mode=<mode>``
+        Select deinterlacing algorithm. Note that by default deinterlacing is
+        initially always off, and needs to be enabled with the ``D`` key
+        (default key binding for ``cycle deinterlace``).
+
+        no
+            Don't allow deinterlacing.
+        first-field
+            Show only first field (going by ``--field-dominance``).
+        bob
+            bob deinterlacing (default).
+
+    ``scaled-osd=<yes|no>``
+        If enabled, then the OSD is rendered at video resolution and scaled to
+        display resolution. By default, this is disabled, and the OSD is
+        rendered at display resolution if the driver supports it.
+
 ``null``
     Produces no video output. Useful for benchmarking.