D2V Source for VapourSynth (Example)
------------------------------------

As the title says, this is a D2V parser and decoder for VapourSynth.
There's not much else to say, so let's get right to an example:

    import vapoursynth as vs

    core = vs.get_core()

    core.std.LoadPlugin(path=r'C:\path\to\d2vsource.dll')

    ret = core.d2v.Source(input=r'C:\path\to\my.d2v')

    ret.set_output()

Parameters:
    input   - Full path to input D2V file.
    nocrop  - Always use direct-rendered buffer, which may need cropping.
              Provides a speedup when you know you need to crop your image
              anyway, by avoiding extra memcpy calls.
    rff     - Invoke ApplyRFF (True by default)
    threads - Number of threads FFmpeg should use. Default is 0 (auto).


About RFF Flags
---------------

Unlike DGDecode, it's up to the user to apply RFF flags as they see fit,
by passing rff=True to the source function, or by passing rff=False and
using core.d2v.ApplyRFF(clip, d2v=r'C:\path\to\my.d2v') after calling
the source function. Unless you know your source is 100% FILM, you
probably want to apply these. DGDecode's traditional "Force FILM" mode
isn't really present in this plugin, but if your source or part of it
is 100% FILM, which is the only time you should be Force FILMing anyway,
you can simply set Force FILM in DGIndex, which will set the framerate
properly in the D2V file, and then not apply RFF flags. It's also
feasible to trim away any non-FILM frames and still Force FILM.


Parameters:
    clip - Input clip.
    d2v  - D2V file for parsing RFF flags. This will be optional
           in the future, once VapourSynth gets global metadata
           support.


Known Limitations & Bugs
------------------------

* Only works with D2V files created by DGIndex (version flag 16) or D2VWitch
  (https://github.com/dubhater/D2VWitch).
* Not all the IDCT algorithms in DGDecode are in libavcodec, so I've tried to
  map them as best I could. See idct_algo_conv in d2v.hpp for more info.
* Does not support user specified cropping. Would be easy to add, but I disagree
  with the premise. Use VapourSynth's cropping.
* Needs the full path to the D2V file.
* Probably more I'm forgetting!


How to Build
------------

At some point I will add a proper build system.

On Windows (Visual Studio):

    Install FFmpeg using vcpkg and then use the included Visual Studio solution.

    Please note that MinGW-built FFmpeg will be faster than one build with Visual
    Studio, due to its use of inline assembly. Also note that only MinGW-w64 is
    supported.

On Linux, Mac OS X, or MinGW:

    ./autogen.sh
    ./configure
    make
    make install