The new API works like the new vaapi API, using generic hwaccel support.
One minor detail is the error message that will be printed if using
non-4:2:0 surfaces (which as far as I can tell is completely broken in
the nVidia drivers and thus not supported by mpv). The HEVC warning
(which is completely broken in the nVidia drivers but should work with
Mesa) had to be added to the generic hwaccel code.
This also trashes display preemption recovery. Fuck that. It never
really worked. If someone complains, I might attempt to add it back
somehow.
This is the 4th iteration of the libavcodec vdpau API (after the
separate decoder API, the manual hwaccel API, and the automatic vdpau
hwaccel API). Fortunately, further iterations will be generic, and not
require much vdpau-specific changes (if any at all).
Use the libavutil vdpau frame allocation code instead of our own "old"
code. This also uses its code for copying a video surface to normal
memory (used by vdpau-copy).
Since vdpau doesn't really have an internal pixel format, 4:2:0 can be
accessed as both nv12 and yuv420p - and libavutil prefers to report
yuv420p. The OpenGL interop has to be adjusted accordingly.
Preemption is a potential problem, but it doesn't break it more than it
already is.
This requires a bug fix to FFmpeg's vdpau code, or vdpau-copy (as well
as taking screenshots) will fail. Libav has fixed this bug ages ago.
For now, this affects taking screenshots only.
If the video mixer is actually needed, we want to go through the video
mixer for screenshots too - which is why this function simply always
used the video mixer, and then copied the surface to RAM as RGBA.
Add reading the surface as nv12 if possible. If the format is correct,
and no special video processing (like deinterlacing) is used, then it's
read directly without going through the video mixer.
There's no particular reason for doing this, other than avoiding the
video mixer (like vo_opengl can do it now). Also, the next commit will
make use of this in vf_vdpaurb.c.
Another fix for the crazy and insane nvidia preemption behavior.
This time, the situation is that we are using vo_opengl with vdpau
interop, and that vdpau got preempted in the background while mpv was
sitting idly. This can be e.g. reproduced by using:
--force-window=immediate --idle --hwdec=vdpau
and switching VTs. Then after switching back, load a video file.
This will not let mp_vdpau_handle_preemption() perform preemption
recovery, simply because it will do so only once vdp_decoder_create()
has been called. There are some other API calls which trigger
preemption, but many don't.
Due to the way the libavcodec API works, vdp_decoder_create() is way too
late. It does so when get_format returns. It notices creating the
decoder fails, and continues calling get_format without the vdpau
format. We could perhaps force it to reinit again (by adding a call to
vdpau.c, that checks for preemption, and sets hwdec_request_reinit), but
this seems too much of a mess.
Solve it by calling API in mp_vdpau_handle_preemption() that empirically
does trigger preemption: output_surface_put_bits_native(). This call is
useless, and in fact should be doing nothing (empty update VdpRect).
There's the slight chance that in theory it will slow down operation,
but in practice it's bound to be harmless. It's the likely cheapest and
simplest API call I've found that can trigger the fallback this way.
(The driver is closed source, so it was up to trial & error.)
Also, when initializing decoding, allow initial preemption recovery,
which is needed to pass the test mention above.
When using --hwdec=auto, about half of all systems will print:
"[vdpau] Error when calling vdp_device_create_x11: 1"
this happens because usually mpv will be linked against both vdpau and
vaapi libs, but the drivers are not necessarily available. Then trying
to load a driver will fail. This is a normal part of probing, but the
error messages were printed anyway. Silence them by explicitly
distinguishing probing.
This pretty much goes through all the layers. We actually consider
loading hw backends for vo_opengl always "auto probed", even if a hw
backend is explicitly requested. In this case vd_lavc will print a
warning message anyway (adjust this message a bit).
Instead of converting the hw surface to an image in the VO, provide a
generic way to convet hw surfaces, and use this in the screenshot code.
It's all relatively straightforward, except vdpau is being terrible. It
needs a huge chunk of new code, because copying back is not simple.
Before this commit, each hw backend had their own specific struct types
for context, and some, like VDA, had none at all. Add a context struct
(mp_hwdec_ctx) that provides a somewhat generic way to pass the hwdec
context around. Some things get slightly better, some slightly more
verbose.
mp_hwdec_info is still around; it's still needed, but is reduced to its
role of handling delayed loading of the hwdec backend.
Same as with the previous commits.
In theory, vdpau/x11 GL interop doesn't assume GLX. It could use EGL as
well. But since it's always GLX in practice, so we're fine with this.
Remove the gl_hwdec.mpgl field - it's unused now.
mpv supports two hardware decoding APIs on Linux: vdpau and vaapi. Each
of these has emulation wrappers. The wrappers are usually slower and
have fewer features than their native opposites. In particular the libva
vdpau driver is practically unmaintained.
Check the vendor string and print a warning if emulation is detected.
Checking vendor strings is a very stupid thing to do, but I find the
thought of people using an emulated API for no reason worse.
Also, make --hwdec=auto never use an API that is detected as emulated.
This doesn't work quite right yet, because once one API is loaded,
vo_opengl doesn't unload it, so no hardware decoding will be used if the
first probed API (usually vdpau) is rejected. But good enough.
Integrate it with the existing surface allocator in vdpau.c. The changes
are a bit violent, because the vdpau API is so non-orthogonal: compared
to video surfaces, output surfaces use a different ID type, different
format types, and different API functions.
Also, introduce IMGFMT_VDPAU_OUTPUT for VdpOutputSurfaces wrapped in
mp_image, rather than hacking it. This is a bit cleaner.
Preparation so that various things related to video can run in different
threads. One part to this is making the video surface pool safe.
Another issue is the preemption mechanism, which continues to give us
endless pain. In theory, it's probably impossible to handle preemption
100% correctly and race-condition free, unless _every_ API user in the
same process uses a central, shared mutex to protect every vdpau API
call. Otherwise, it could happen that one thread recovering from
preemption allocates a vdpau object, and then another thread (which
hasn't recovered yet) happens to free the object for some reason. This
is because objects are referenced by integer IDs, and vdpau will reuse
IDs invalidated by preemption after preemption.
Since this is unreasonable, we're as lazy as possible when it comes to
handling preemption. We don't do any locking around the mp_vdpau_ctx
fields that are normally immutable, and only can change when recovering
from preemption. In practice, this will work, because it doesn't matter
whether not-yet-recovered components use the old or new vdpau function
pointers or device ID. Code calls mp_vdpau_handle_preemption() anyway to
check for the preemption event and possibly to recover, and that
function acquires the lock protecting the preemption state.
Another possible source of potential grandiose fuckup is the fact that
the vdpau library is in fact only a tiny wrapper, and the real driver
lives in a shared object dlopen()ed by the wrapper. The wrapper also
calls dlclose() on the loaded shared object in some situations. One
possible danger is that failing to recreate a vdpau device could trigger
a dlclose() call, and that glibc might unload it. Currently, glibc
implements full unloading of shared objects on the last dlclose() call,
and if that happens, calls to function pointers pointing into the shared
object would obviously crash. Fortunately, it seems the existing vdpau
wrapper won't trigger this case and never unloads the driver once it's
successfully loaded.
To make it short, vdpau preemption opens up endless depths of WTFs.
Another issue is that any participating thread might do the preemption
recovery (whichever comes first). This is easier to implement. The
implication is that we need threadsafe xlib. We just hope and pray that
this will actually work. This also means that once vdpau code is
actually involved in a multithreaded scenario, we have to add
XInitThreads() to the X11 code.
Use the newly provided mp_vdpau_handle_preemption() function, instead of
accessing mp_vdpau_ctx fields directly. Will probably make multithreaded
access to the vdpau context easier.
Mostly unrelated to the actual changes, I've noticed that using hw
decoding with vo_opengl sometimes leads to segfaults inside of nvidia's
libGL when doing the following:
1. use hw decoding + vo_opengl
2. switch to console (will preempt on nvidia systems)
3. switch back to X (mpv will recover, switches to sw decoding)
4. enable hw decoding again
5. exit mpv
Then it segfaults when mpv finally calls exit(). I'll just blame nvidia,
although it seems likely that something in the gl_hwdec_vdpau.c
preemption handling triggers corner cases in nvidia's code.
This was broken for some time, and it didn't recover correctly.
Redo decoder display preemption. Instead of trying to reinitialize the
hw decoder, simply fallback to software decoding. I consider display
preemption a bug in the vdpau API, so being able to _somehow_ recover
playback is good enough.
The approach taking here will probably also make it easier to handle
multithreading.
This was a minor code duplication between vf_vdpaupp.c and vo_vdpau.c.
(In theory, we could always require using vf_vdpaupp with vo_vdpau, but
I think it's better if vo_vdpau can work standalone.)
They were used by ancient libavcodec versions. This also removes the
need to distinguish vdpau image formats at all (since there is only
one), and some code can be simplified.
Instead of generating vdpau_template.c with a Perl script, just include
the generated file in git. This is ok because it changes very rarely,
and the script is larger than the output it generates.
It also simplify the Makefile, and fixes the build. The problem was that
transitive dependencies do not work with generated files: there is no
dependency information yet when building it the first time. I overlooked
this because I didn't delete the .d files for testing (which contained
the correct dependencies, but only _after_ a first successful build).
Move the decoder parts from vo_vdpau.c to a new file vdpau_old.c. This
file is named so because because it's written against the "old"
libavcodec vdpau pseudo-decoder (e.g. "h264_vdpau").
Add support for the "new" libavcodec vdpau support. This was recently
added and replaces the "old" vdpau parts. (In fact, Libav is about to
deprecate and remove the "old" API without deprecation grace period,
so we have to support it now. Moreover, there will probably be no Libav
release which supports both, so the transition is even less smooth than
we could hope, and we have to support both the old and new API.)
Whether the old or new API is used is checked by a configure test: if
the new API is found, it is used, otherwise the old API is assumed.
Some details might be handled differently. Especially display preemption
is a bit problematic with the "new" libavcodec vdpau support: it wants
to keep a pointer to a specific vdpau API function (which can be driver
specific, because preemption might switch drivers). Also, surface IDs
are now directly stored in AVFrames (and mp_images), so they can't be
forced to VDP_INVALID_HANDLE on preemption. (This changes even with
older libavcodec versions, because mp_image always uses the newer
representation to make vo_vdpau.c simpler.)
Decoder initialization in the new code tries to deal with codec
profiles, while the old code always uses the highest profile per codec.
Surface allocation changes. Since the decoder won't call config() in
vo_vdpau.c on video size change anymore, we allow allocating surfaces
of arbitrary size instead of locking it to what the VO was configured.
The non-hwdec code also has slightly different allocation behavior now.
Enabling the old vdpau special decoders via e.g. --vd=lavc:h264_vdpau
doesn't work anymore (a warning suggesting the --hwdec option is
printed instead).
