path: root/DOCS
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authorwm4 <wm4@nowhere>2013-03-28 21:44:27 +0100
committerwm4 <wm4@nowhere>2013-03-28 21:46:17 +0100
commit8099cbe9dd64f48050918242e088a1f998c77a15 (patch)
tree76abcee94beef81308e3d9f871161f3595006a21 /DOCS
parent69c4baad91b953afbd0ea9b76b57a7040812bb24 (diff)
vo_opengl: add alpha output
Allows playing video with alpha information on X11, as long as the video contains alpha and the window manager does compositing. See vo.rst. Whether a window can be transparent is decided by the choice of the X Visual used for window creation. Unfortunately, there's no direct way to request such a Visual through the GLX or the X API, and use of the XRender extension is required to find out whether a Visual implies a framebuffer with alpha used by XRender (see for example [1]). Instead of depending on the XRender wrapper library (which would require annoying configure checks, even though XRender is virtually always supported), use a simple heuristics to find out whether a Visual has alpha. Since getting it wrong just means an optional feature will not work as expected, we consider this ok. [1] rendering-context-with-transparent-background/9215724#9215724
Diffstat (limited to 'DOCS')
1 files changed, 8 insertions, 0 deletions
diff --git a/DOCS/man/en/vo.rst b/DOCS/man/en/vo.rst
index e3b8723966..dcfcb05278 100644
--- a/DOCS/man/en/vo.rst
+++ b/DOCS/man/en/vo.rst
@@ -430,6 +430,14 @@ opengl
dimension. Default is 128x256x64.
Sizes must be a power of two, and 256 at most.
+ alpha
+ Try to create a framebuffer with alpha component. This only makes sense
+ if the video contains alpha information (which is extremely rare). May
+ not be supported on all platforms. If alpha framebuffers are
+ unavailable, it silently falls back to a normal framebuffer. Note
+ that when using FBO indirections (such as with ``opengl-hq``), a FBO
+ format with alpha must be specified with the ``fbo-format`` option.
Same as ``opengl``, but with default settings for high quality rendering.