This allows vo_opengl to use GL_TEXTURE_RECTANGLE textures, either by
enabling it with the 'rectangle-textures' sub-option, or by having a
hwdec backend force it. By default it's off.
The _only_ reason we're adding this is because VDA can export rectangle
textures only.
Improves display of images and video with alpha channel, especially if
the transparent regions contain (supposed to be invisible) garbage
color values.
Until now, only formats directly supported by OpenGL were supported.
This excludes various permutations of 8-bit RGB[A|0]. But we can simply
permutate the color channels in the shader, so do that. This also adds
support for all these weird RGB0 formats.
Note that we could use libavutil's pixfmt list instead of the
mp_packed_formats array, but trying to decrypt the pixfmt info would
probably end in pain, so this array with duplicated information is
actually better and shorter.
Note: I didn't actually test whether the alpha components are reproduced
correctly with alpha formats.
Use the video decoder chroma location flags and render chroma locations
other than centered. Until now, we've always used the intuitive and
obvious centered chroma location, but H.264 uses something else.
FFmpeg provides a small overview in libavcodec/avcodec.h:
-----------
/**
* X X 3 4 X X are luma samples,
* 1 2 1-6 are possible chroma positions
* X X 5 6 X 0 is undefined/unknown position
*/
enum AVChromaLocation{
AVCHROMA_LOC_UNSPECIFIED = 0,
AVCHROMA_LOC_LEFT = 1, ///< mpeg2/4, h264 default
AVCHROMA_LOC_CENTER = 2, ///< mpeg1, jpeg, h263
AVCHROMA_LOC_TOPLEFT = 3, ///< DV
AVCHROMA_LOC_TOP = 4,
AVCHROMA_LOC_BOTTOMLEFT = 5,
AVCHROMA_LOC_BOTTOM = 6,
AVCHROMA_LOC_NB , ///< Not part of ABI
};
-----------
The visual difference is literally minimal, but since videophiles
apparently consider this detail as quality mark of a video renderer,
support it anyway. We don't bother with chroma locations other than
centered and left, though.
Not sure about correctness, but it's probably ok.
This could lead to quite visible artifacts when using an appropriate ICC
and float FBOs. The float FBOs allow storing out of range values, and my
guess is that the rest of the precessing chain elevated these out of
range values, resulting in artifacts.
This might be better with dumb shader compilers, which won't vectorize
this to a single vector-division, assuming the hardware does have such
an instruction. Affects "bicubic_fast" scale mode only.
The internal texture format GL_RED is typically 8 bit, which is clearly
not good enough for the new dither matrix. The idea was to use a float
texture format, but this was somehow "forgotten". Use GL_R16, since
16 bit textures are more robust, and provide more precision for the
same memory usage.
Change how the offset for centering the dither matrix is applied. This
is needed for making it possible to round up values to the target depth.
Before this commit, this changed the output even if the input was exact
and input and output depth were the same, which is not really what you
want. Now it doesn't do that anymore.
Use a different algorithm to generate the dithering matrix. This
looks much better than the previous ordered dither matrix with its
cross-hatch artifacts.
The matrix generation algorithm as well as its implementation was
contributed by Wessel Dankers aka Fruit. The code in dither.c is
his implementation, reformatted and with static global variables
removed by me.
The new matrix is uploaded as float texture - before this commit, it
was a normal integer fixed point matrix. This means dithering will
be disabled on systems without float textures.
The size of the dithering matrix can be configured, as the matrix is
generated at runtime. The generation of the matrix can take rather
long, and is already unacceptable with size 8. The default is at 6,
which takes about 100 ms on a Core2 Duo system with dither.c compiled
at -O2, which I consider just about acceptable.
The old ordered dithering is still available and can be selected by
putting the dither=ordered sub-option. The ordered dither matrix
generation code was moved to dither.c. This function was originally
written by Uoti Urpala.
Useful for the j2k decoder.
Matrix taken from http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
(XYZ to sRGB, whitepoint D65)
Gamma conversion follows what libswscale does (2.6 in, 2.2 out).
If linear RGB is used internally for scaling, the gamma conversion
will be undone by setting the exponent to 1. Unfortunately, the two
gamma values don't compensate each others exactly (2.2 vs. 1/0.45=2.22...),
so output is a little bit incorrect in sRGB or color-managed mode. But
for now try hard to match libswscale output, which may or may not be
correct.
The previous attempt was missing some code paths, so there were still
shaders generated that triggered the shader compilation error. Fix it
instead by special handling USE_CONV in the shader.
By the way, the shader compiler did not accept:
#if defined(USE_CONV) && (USE_CONV == ...)
In my opinion this should be perfectly fine, but it gives the same
error as before. So test USE_CONV separately with #ifndef.
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] http://stackoverflow.com/questions/4052940/how-to-make-an-opengl-rendering-context-with-transparent-background/9215724#9215724
gl_video.c contains all rendering code, gl_lcms.c the .icc loader and
creation of 3D LUT (and all LittleCMS specific code). vo_opengl.c is
reduced to interfacing between the various parts.
wm4
Martin Herkt