This makes vo_opengl_cb respond to controls like "gamma" and
"brightness". The commit includes an awkward refactor for vo_opengl to
make it easier for vo_opengl_cb.
One problem is a logical race condition. The set of supported controls
depends on the pixelformat, which in turn is set by reconfig(). But the
actual reconfig() call (on the renderer) happens asynchronously on the
renderer thread. At the time it happens, the player most likely already
tried to set some controls for command line options (see init_vo() in
video.c). So setting this command line options will fail most of the
time, though it could randomly succeed. This can't be fixed directly,
because the player can't wait on the renderer thread, because the
renderer thread might already wait on the player.
Until now, calling mpv_opengl_cb_uninit_gl() at a "bad moment" could
make the whole thing to explode. The API user was asked to avoid such
situations by calling it only in "good moments". But this was probably a
bit too subtle and could easily be overlooked.
Integrate the approach the qml example uses directly into the
implementation. If the OpenGL context is to be unitialized, forcefully
disable video, and block until this is done.
GL_ARB_debug_output provides a logging callback, which can be used to
diagnose problems etc. in case the driver supports it. It's enabled only
if the vo_opengl "debug" suboption is set.
Now it accepts the same renderer arguments as vo_opengl. This also
disables debug checks by default, and reverts the background color
override. Both can now be controlled by the host application.
Commit d38bc531 is incorrect: the 50ms queue-ahead value and the flip
queue offset have different functions. The latter is about calling
flip_page in advance, so the change attempted to show video frames 50ms
in advance on all VOs.
The change was for vo_opengl_cb, but that can be handled differently.
I think that's expected; mpv shouldn't draw anything while no video is
active. This doesn't blend transparently, though.
Also document the vo_opengl_cb thing.
This adds API to libmpv that lets host applications use the mpv opengl
renderer. This is a more flexible (and possibly more portable) option to
foreign window embedding (via --wid).
This assumes that methods like context sharing and multithreaded OpenGL
rendering are infeasible, and that a way is needed to integrate it with
an application that uses a single thread to render everything.
Add an example that does this with QtQuick/qml. The example is
relatively lazy, but still shows how relatively simple the integration
is. The FBO indirection could probably be avoided, but would require
more work (and would probably lead to worse QtQuick integration, because
it would have to ignore transformations like rotation).
Because this makes mpv directly use the host application's OpenGL
context, there is no platform specific code involved in mpv, except
for hw decoding interop.
main.qml is derived from some Qt example.
The following things are still missing:
- a way to do better video timing
- expose GL renderer options, allow changing them at runtime
- support for color equalizer controls
- support for screenshots
wm4