The ARB shader code generated at the end of the shaders for scaling mode 4
and 5 was something like:
MAD yuv.g, b.r, {0.5}, a.r;
This appears to be semantically equivalent with:
MAD yuv.g, b.rrrr, {0.5, 0, 0, 0}, a.rrrr;
This has the consequence that the result register, yuv.g, will not contain
the value computed by the scale filter, but a.r. a.r is the unchanged
value sampled from the normal texture coordinates, so the filter did
effectively nothing and behaved as if cscale=0 was specified. The basic
mistake here is that yuv.g does not specify a single register, but it
specifies the full vector register yuv, with writing enabled on the g
channel. This means yuv.g will assigned the g channel of the the result
vector computed by the MAD instruction.
Compiling with full features requires development files for several
external libraries. Below is a list of some important requirements. For
more information see the output of './configure --help' for a list of options,
or look at the list of enabled and disabled features printed after running
'./configure'. If you think you have support for some feature installed
but configure fails to detect it, the file config.log may contain information
about the reasons for the failure.
Libraries specific to particular video output methods
(you'll want at least one of VDPAU, GL or Xv):
- libvdpau (for VDPAU output, best choice for NVIDIA cards)
- libGL (OpenGL output)
- libXv (XVideo output)
general:
- libasound (ALSA audio output)
- various general X development libraries
- libfreetype
- libfontconfig
- libass
- FFmpeg libraries (libavutil libavcodec libavformat libswscale libpostproc)
Most of the above libraries are available in suitable versions on normal
Linux distributions. However FFmpeg is an exception (distro versions may be
too old to work at all or work well). For that reason you may want to use
the separately available build wrapper that first compiles FFmpeg libraries
and libass, and then compiles the player statically linked against those.
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