Filter SDK/InvertNeg

Revision as of 17:49, 24 August 2013

I'll start off with a complete, working Avisynth plugin. It's called "InvertNeg", and it produces a photo-negative of the input clip.

Here's InvertNeg.cpp:

#include <windows.h>
#include "avisynth.h"

class InvertNeg : public GenericVideoFilter {
public:
   InvertNeg(PClip _child, IScriptEnvironment* env);
   PVideoFrame __stdcall GetFrame(int n, IScriptEnvironment* env);
};

InvertNeg::InvertNeg(PClip _child, IScriptEnvironment* env) :
   GenericVideoFilter(_child) {
   if (!vi.IsPlanar() || !vi.IsYUV()) {
      env->ThrowError("InvertNeg: planar YUV data only!");
   }
}

PVideoFrame __stdcall InvertNeg::GetFrame(int n, IScriptEnvironment* env) {

   PVideoFrame src = child->GetFrame(n, env);
   PVideoFrame dst = env->NewVideoFrame(vi);

   const unsigned char* srcp;
   unsigned char* dstp;
   int src_pitch, dst_pitch, int row_size, height;
   int p, x, y;

   int planes[] = {PLANAR_Y, PLANAR_V, PLANAR_U};
	
   for (p=0; p<3; p++) {
      srcp = src->GetReadPtr(planes[p]);
      dstp = dst->GetWritePtr(planes[p]);

      src_pitch = src->GetPitch(planes[p]);
      dst_pitch = dst->GetPitch(planes[p]);
      row_size = dst->GetRowSize(planes[p]);
      height = dst->GetHeight(planes[p]);

      for (y = 0; y < height; y++) {
         for (x = 0; x < row_size; x++) {
            dstp[x] = srcp[x] ^ 255;
         }
         srcp += src_pitch;
         dstp += dst_pitch;
      }
   }
   return dst;
}

AVSValue __cdecl Create_InvertNeg(AVSValue args, void* user_data, IScriptEnvironment* env) {
   return new InvertNeg(args[0].AsClip(), env);
}
const AVS_Linkage *AVS_linkage = 0;

extern "C" __declspec(dllexport) const char* __stdcall AvisynthPluginInit3(IScriptEnvironment* env, const AVS_Linkage* const vectors) {
   AVS_linkage = vectors;
   env->AddFunction("InvertNeg", "c", Create_InvertNeg, 0);
   return "InvertNeg sample plugin";
}

Compile this file into a DLL named InvertNeg.dll. See compiling instructions xxx. Now create an Avisynth script which looks something like this:

LoadPlugin("d:\path\InvertNeg.dll")
clip = BlankClip().ConvertToYV12()
return clip.InvertNeg()

line by line breakdown

A line by line breakdown of the code above.

xxx

--

refer to old versions:

Ben's AviSynth Docs is the documentation written for AviSynth 1.0 by Ben Rudiak-Gould, in its original form.

See more about the modifications for AviSynth 2.5 in the AviSynth Two-Five SDK.